General Organic Chemistry I Laboratory CHEM 212
Lab & Exam Schedule & Experiments ~FALL 2018~ Zubrick Lab Date What’s due? Week Exp.# Prelab (PL), Report Text Topic 2018 (R) Chapters Safety Contract, Introduction, Safety, Check-in 1 8-14 1 1-9 Check-in Sheet Scavenger Hunt: Chemistry Research and Calculations Melting Point: Single Compound & Mixed Melting 2 8-21 2 PL: 2 12 Points. Identification of Unknown Compound PL: 3 19, 20, 34 Distillation: Single Compounds & Mixtures using 3 8-28 3 R: 2 (4,5,6,8,18) Simple, Fractional & Microscale (Hickman) Distillation R: 3 4 9-4 1 (Cont’d) 1-9 Continue Scavenger Hunt –We will not meet Tuesday Due Wed. Sept 5 R:1 5 9-11 EXAM 1 Exam 1 review Extraction, Sublimation& Purification of Caffeine 5 (Dry lab)* *end of lab 10,11,15,16, 6 9-18 * Completed in lab: [Data given] Prelab, Data, Report, Yes, Exp 5 PL:5, R:5 23,24, 35 before Exp 4 Conclusion, & Sources of Error all together as one unit. 4 Compound Synthesis & Purification using 7 9-25 PL: 4 13,14 Recrystallization Campus Due Wed. Oct 3 8 10-3** Closed Tues R: 4 EXAM 2** (Wednesday) Oct 2 Exam 2 review Molecular Models: Alkane, Alkene, Alkyne & Cyclic 9 10-9 6 Nothing Compounds Properties, Synthesis and Reactions 10 10-16 7 PL: 7 26-28, 30-31 Chromatography: Partition and Adsorption, Check-out R:6 & R:7 11 10-23 EXAM 3 Exam 3 review Spectroscopy: Interpretation, Analysis, & Identification 12 10-30 8 Formal Report 32, 33 of Compounds using IR, MS, HMNR & CNMR Spectroscopy Spectroscopy: Interpretation, Analysis, & Identification 13 11-6 8 (Cont’d) 32, 33 Workbook of Compounds using IR, MS, HMNR & CNMR Spectroscopy: Interpretation, Analysis, & Identification 14 11-13 8 (Cont’d) DUE Wed 11-14: IR/MS paper of Compounds using IR, MS, HMNR & CNMR 15 11-20 Exam 4 review EXAM 4 DUE Wed 11-28: CNMR, HNMR, Spectroscopy: Interpretation, Analysis, & Identification 16 11-27 8 (Cont’d) UV/VIS paper of Compounds using IR, MS, HMNR & CNMR DUE Mon 12-3: Spec. Problems Spectroscopy: Interpretation, Analysis, & Identification 17 12-4 8 (Cont’d) and exercises of Compounds using IR, MS, HMNR & CNMR 12-10 Return Loaned Books: You must turn in loaned books before final 18 exam to get a final exam. Except if you are enrolled in CHEM 213. Final Exam (TBD) ______@ 7:30 am Key Due Dates (all due before 7:20 am): Formal lab report on either exp. 2, 3, 4, or 7 (20 points) Tues. Oct 30th Typed Research Paper on IR and MS (20 points) Wed. Nov 14th Typed Research Paper on NMR and UV-VIS (20 points) Wed. Nov 28th McMurry Chapter problems and exercises (20 points) Mon. Dec. 3rd All lab reports are due 1 week after the experiment was scheduled, before 7:20 am on a lab or exam day. NO LATE REPORTS, ASSIGNMENTS NOR PAPERS ACCEPTED. Technological problems (printer, computer, disks, etc.) are not acceptable excuses for late reports or papers, so start early.
1 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Labs: For each experiment, you are responsible to prepare and read over lab text and lab notes to understand the general principles. For the pre-lab (PL) assignment, you are required to turn in a purpose and procedure (outline) for the experiment before lab starts, see below for more details. The purpose and procedure is written in your lab notebook and the carbon copy given to me. If you do not turn in the purpose/procedure on time, you will not be able to perform that experiment. No makeup labs allowed. I will start every lab with a short discussion of safety and lab technique. If you arrive late, I cannot allow you to perform the experiment. I will not tell you how to do the experiment step by step. You are responsible to have read the material with an understanding of the experiment and what you need to do before you come to lab. If I feel you are unprepared for the lab, you will be asked to leave without credit for the experiment and no makeup lab allowed.
You are responsible for understanding the information in your lab text: The Organic Chem Lab Survival Manual, J. Zubrick. The lab text is your guide to organic lab techniques required for this course. For example, if the directions ask you to recrystallize a compound, look up recrystallization techniques in your lab text. Standard laboratory techniques, safety, and brief theoretical discussions are described in the text. It is your responsibility to read and understand the information before you come into lab to perform the experiments. If I feel you are not properly prepared for the experiment, you will be asked to leave the lab, no credit will be given for the experiment, and no make-up lab is allowed.
Laboratory Report: You are required to complete a laboratory report, which is graded on a 20-point basis, for each experiment you perform in the laboratory. All lab reports are due 1 week after lab is scheduled, before the lab or the exam starts. Late reports will not be accepted for any reason. If you know you cannot attend, then you may turn it in early or have a student turn in the report on time for you. I do not accept laboratory reports via electronic means.
Lab Report: Items due before, or at the end of lab a) Purpose: Written in your lab notebook along with the procedure, and the copy turned into me before the lab starts. The purpose is the reason for doing the experiment; it is a few sentences, or a short paragraph. The purpose must also include any reactions or equations. (2 pts) b) Procedure: Written in your lab notebook along with the purpose and usually on the same page, and the copy turned into me before the lab starts. The procedure must be in enough detail, so that the experiment can be performed from just your notes. This must include a clearly labelled list of materials and equipment needed, and a brief and clearly labelled sketch of all the lab apparatus and set up. (3pts) c) Data: This is written in your lab notebook on a different page from the purpose and procedure. It should be prepared before you come to lab so that during the experiment, all you need to do is fill in the data and turn in the copy to me as you leave, at the end of lab. (1 pt)
Lab Report: Items due the following week
Report: Completed report page(s) included in this packet plus; attach the page(s) written in your lab notebook, clearly label each section: calculations, graphs, conclusion**, and sources of error.
**The conclusion must include results such as MP, unknown number and identity, % yield, etc. Questions on the report pages need to be answered directly on that page, and not written in lab notebook. (14 pts)
2 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
CHEM 212: Key Concepts for Experiments & Calculation Formulas Be sure to use the analytical balances only for all mass measurements to obtain proper significant digits.
Key concepts for Experiment 1: Scavenger Hunt Learn how to use printed material to access information; CRC, Acros Catalog, Zubrick Lab text. Learn how to electronic (digital) material such as the internet to access information. Compare websites and printed material for accuracy and reliability of information. Tour the CHC chemical stockroom to learn safety and other organization. Meet with a CHC Transfer Advocate to learn about transfer options and careers. Review calculations that should have been mastered in perquisite course of general chemistry that will be used in OCHEM.
Key concepts for Experiment 2: Melting Point Learn* how to determine melting points using the DigiMelt apparatus. Perform melting points of pure compounds of urea and trans-cinnamic acid. Learn that melting points are reported as ranges, first list start temperature, and then clear point. Prepare and perform mixed melting points of 50/50 mixture of urea and trans-cinnamic acid. Learn what an impurity will do to a melting point. Identify an unknown compound using melting point and mixed melting point. (*Do not include learning concepts in purpose of the experiment).
Key concepts for Experiment 3: Distillation Learn how to set up and use macroscale simple and fractional distillation apparatus. Learn how to set up and use microscale distillation apparatus such as a Hickman Still. Use simple distillation to determine the boiling point of hexane. Prepare a mixture of hexane & toluene and perform a simple distillation, then a fractional distillation on the mixture. Graphing of data, then determine boiling points from graph. Compare effectiveness of simple vs. fractional distillation of a mixture for determining boiling point. Learn that boiling points are reported as a single temperature.
Key concepts for Experiment 4: Recrystallization To purify a contaminated sample using hot gravity filtration, recrystallization of crude product, vacuum filtration and washing of purified product. Learn lab technique of hot gravity filtration and vacuum filtration using a Büchner funnel. Recrystallize a crude compound to purify. Obtain MP of recrystallized product to determine purity. Calculate percent yield.
Key concepts for Experiment 5: Extraction, Sublimation and Purification of Caffeine Perform a sublimation of caffeine. Perform an organic/aqueous extraction of caffeine. Learn proper way to use separatory funnel. Use of gravity filtration and drying agent to isolate caffeine. Calculate distribution coefficient KD. Use to identify preference of organic or aqueous layer.
Key concepts for Experiment 6: Molecular Models A detailed summary of alkane, alkene, alkyne, and cycloalkane compounds information, such as; structure, nomenclature, chemical properties, synthesis and reactions. Key concepts for Experiment 7: Chromatography Learn how to setup and perform paper chromatography. Separate colors in food coloring using 2:1, n-propyl alcohol:water as the solvent in the mobile phase. Calculate Rf value of each separated colors in paper chromatography, then report trend/average for blue, yellow and red. Learn how to setup and prepare a chromatography column. Use column to separate colors in green dye, determine which solvent each color has an affinity for. 3 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
To calculate Theoretical Yields and determine Limiting Reactants:
The theoretical yield of a reaction is the amount of product that would be formed if the reaction went to completion. It is based on the stoichiometry of the reaction and ideal conditions in which starting material is completely consumed, undesired side reactions do not occur, the reverse reaction does not occur, and there no losses in the work-up procedure.
In order to calculate the theoretical yield, you must first balance the reaction. Then, look closely to determine which reagents are being used in excess and which is the limiting reagent. The overall yield of product depends on the limiting reagent. Remember that catalysts, solvents, or any compounds that are not part of the actual chemical reaction cannot be the limiting reagent. Theoretical yield calculations are carried out in the same way as they were in general chemistry: the moles of limiting reactant determine the moles of product.
Balance the reaction and determine the stoichiometry or ratios of reactants to products. Calculate amount of product in grams that would form from each of the reactants. There will usually be 2 of these to calculate. (Remember units).
Stoichiometry Map:
grams moles moles grams A use MM A use Mole ratio B use MM B of A (rxn coefficients) of B
Choose the smaller of the 2 amounts calculated for the product. This is the theoretical yield of the product. The reactant which produces the smaller amount is the limiting reactant.
To calculate Percent Yield:
After your laboratory reaction is complete, you will isolate and measure the amount of product, then compare the actual yield to the theoretical yield to determine the percent yield:
actual yield (in grams) 100% percent yield theoretical yield (in grams)
In the laboratory, the percent yield has the practical aspect of telling the success of your synthesis scheme. A low percentage yield means that the conditions were not optimal and could be improved. Perhaps there are competing reactions occurring or some of the product is being lost in the purification steps.
Notes and Report for Experiment 1:
Be sure to read your lab text The Organic Chemistry Survival Guide for additional information in Chapters 1 - 9. You are responsible for all the information in these chapters, so be sure to read them with an understanding of all the information given. You will be required to implement this information during this course.
The questions for the scavenger hunt follow. Answers to the scavenger hunt questions are to be written on these pages, not in lab notebook. You will not write a purpose or conclusion for this experiment. This experiment takes a lot of time so start early. CRC, MSDS and catalogs are available in CYN-105 the balance room for your use but may not be taken out of the balance room. You will need to use the internet for many sections. The library has a computer mall on the first floor, open during library hours.
4 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 1: Scavenger Hunt Name______
PART A: Old School Style Reference: Using Printed Material for Information
Handbook of Chemistry and Physics (CRC) To get a better understanding of what is available in this publication, answer the following questions using the 93rd edition there are copies of this in the lab room. The 51st edition (also in lab room) is not formatted the same, don’t use it. 1.1 List the Title of each section. These sections will be helpful in this organic chemistry course. Section Title Section Title 1 8 2 13 3 15 7 16
1.2 List the section and page in the CRC number for the following Organic Substituent Groups and Ring Common Mass Spectral Fragmentation Systems Patterns
Structures of Common Amino Acids Structure of naphthalene with numbering system on structure
Miscibility of Organic Solvents 13CNMR Absorptions
Synonym Index of Organic Compounds Definition of Scientific Terms: Chiral Molecule
Proton NMR Absorption of Major Definition of Scientific Terms: Chemical Families Olefins
Chemical Composition of Human Body Definition of Scientific Terms: Aryl Groups
1.3 Reference Section 2 of the CRC to ethyl mercapto benzyl phenyl find the following information:
Write the formulas for the following substituent groups isopentyl vinyl amino propoxy
Acros Organic Catalog: Although this is a catalog to order chemicals, they have made it into a useful reference tool. 1.4 Using the catalog, answer the following about 2-chlorobutane, 99+%.(Year 2002/03 is in the lab room to use) MW Structural Formula BP oC Density Flash Point Refractive Index Cost of 250 mL
5 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Your Organic Chem Lab Survival Manual: Read chapters 1-3. (Keep in mind you will also be responsible for information in chapters 4-9, it is assigned reading during the first 3 weeks). 1.5 List the Title of each Chapter. Submit answers to the following Exercise questions on a separate piece of paper Chapter Title Exercises 1 1,2,6 2 3,4 3 1
PART B: New School Style Reference: Using the Internet for Information 1.6 What does old term MSDS mean? What does the newer term SDS mean?
Go to the following website http://www.ilpi.com/msds/quiz and complete the ILPI’s 7-part multiple choice quiz on SDS (MSDS).
Print out the Certificate of Achievement with your name and turn in with this report.
Comparing websites and information: Use the following internet sites plus one additional internet site of your choice. List the URL of the site you choose. Source 1: Fisher Scientific http://www.fishersci.com (Use the MSDS search), Source 2: Wikipedia, Source 3: Your choice, Source 4: CRC (Handbook of Chemistry and Physics)
1.7 Look up the CAS number for Urea, and list the melting point from each of the following sources, show units. CAS Number: Fisher Scientific Wikipedia Other URL CRC
URL of Source 3:
1.8 Look up the CAS number for trans-cinnamic acid, and list the melting point from each of the following sources, show units. CAS Number: Fisher Scientific Wikipedia Other URL CRC
URL of Source 3:
1.9 Look up the CAS number for toluene, and list the boiling point from each of the following sources, show units. CAS Number: Fisher Scientific Wikipedia Other URL CRC
URL of Source 3:
1.10 Look up the CAS number for 3-methyl-3-pentanol, and list the density from each of the following sources, show units. CAS Number: Fisher Scientific Wikipedia Other URL CRC
URL of Source 3:
6 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
PART C: People you need to meet You are responsible to arrange to meet with these people; you can check office hours for faculty. You may go to meet them with another student but please do not overwhelm them, no more than 1-3 people at a time.
CHC Chemistry Laboratory Technician: 1.12 How is the 1.11 Where are the hard refrigerator in the 1.13 List the shelf location of each of these and the FW from the label copies of the SDS stockroom different on the bottle. located? than the one at your home? Compound Shelf FW
urea
trans-cinnamic acid
Chemical Storage: CYN-109 1.15 What is in the 1.16 What is in 1.17 Why is the AgNO2 1.14 Why are the acid cabinets vented? Flammable the Corrosive stored in a cabinet? cabinets? cabinets?
CHC Transfer Advocate: Visit either Dr. Sam Truong- Health Science Careers or Prof. Ruth Greyraven- Biology Careers or Visit the Transfer Center and see a Transfer Counselor. (STEM Counselor may be available too Answer the following questions and have the Transfer Counselor/Transfer Advocate’s Initials: Advocate initial to the right after you have met. 1.18a Do you already have an undergraduate (BS or BA) 1.18b Do you plan on obtaining an AS degree from CHC? If degree? In what field? yes, in what area?
1.19 What school(s) do you plan on visiting and/or transferring to? What is your Major and terminal degree plan?
CHC Tutor Center: Visit the Tutoring Center. Meet with an OCHEM Tutor Have the OCHEM tutor tell you about the Center & Services Name & Initials of Tutoring Center OCHEM Tutor: and have them initial that you completed the visit. 1.20a List 3 services that are provided. 1.20c What are the current OCHEM tutoring Hours
1.20b How do students set up a study group?
7 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
PART D: Calculations you needed to have mastered for this class. (General Chemistry Calculations)
1.21 Use the balanced reaction and necessary reference books to answer the following questions when 5.0- g propane and 10.0-mL bromine react. Br
H3C CH2 CH3 + 2 Br2 H3C C CH3 + 2 HBr Br Propane bromine 2,2-dibromopropane hydrobromic acid
a. What is the number of moles of propane present before the reaction?
b. Look up the density of molecular bromine and calculate the number of moles present before the reaction.
c. Which is the limiting reactant?
d. Calculate the theoretical yield in grams of 2,2-dibromopropane.
e. Suppose that 15.58 g of 2,2-dibromopropane were actually formed, what is the percent yield of 2,2- dibromopropane?
1.22 Look up the density of 2,2-dibromopropane and calculate the volume of 15.58 g.
1.23 Calculate the number of mmol of HCl in 3.0 μL of 12.0 M HCl.
8 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 2: Melting Point Read the DigiMelt melting point apparatus manual and view the video on how to operate the apparatus posted in Blackboard in the Lab Experiment Tab, and read CHAPTER 12 in your OCHEM Survival Guide.
INTRODUCTION Y are the same compound, the mixture melting point will be the same as the melting point of pure X or pure Y. If X and Y are The melting point of a pure compound is an intensive property, not the same compound, one will act as an impurity in the like density and boiling point. Intensive properties are other and the mixture melting point will be lower and more o independent of the amount of substance present. The melting spread out (wide range 120-125 C in this case) than the individual melting points of pure X or pure Y. point of a compound is the temperature at which it changes
from a solid to a liquid. Experimentally, melting point is Melting point of a solid: the temperature at which the liquid actually recorded as the range of temperatures in which the and solid phases are in equilibrium. first crystal starts to melt until the temperature at which the last crystal just disappears. Sintering shrinkage of a solid being heated, other solids suddenly shrink just before melting solids begin to "sweat" a Reasons for determining melting points: few degrees below their true melting points
1. The melting point indicates the level of purity of a sample. Procedure Notes: An impure compound starts to melt at a lower temperature a. Transfer a small sample using a toothpick onto a watch and melts over a broader range. glass, discard toothpick after single use to avoid contamination. Crush samples for 30 – 60 seconds with a 2. The melting point helps to identify unknown samples, clean, dry stirring rod on the watch glass before loading the narrowing the number of possibilities, because a pure solid capillary. Especially important for mixed MP determinations. melts reproducibly over a narrow range of temperatures. b. The optimal sample size for the DigiMelt is 2-3 mm of packed sample. If the tapper doesn’t load the capillary 3. The melting point helps to characterize new compounds. correctly, use the 1-meter glass tube method. c. Use a ramp rate of 2oC/min for all tests (with the exception In this lab, the identity of an unknown organic compound will in part B, approximate melting point, use a ramp rate of be determined by comparing its experimental melting point to 10oC/min.). those of a variety of known compounds. d. Be sure to see if sample melts immediately or very quickly
when first inserted, this means the starting temperature is Key Terms: above the melting point. Capillary melting point: the temperature range over, which a e. Press sample number to flag the temperatures for each small amount of solid in a thin walled capillary tube first visibly sample, and then recall the data to record on report sheet softens (first drop of liquid) and then completely liquefies. before starting another test. Record all temperatures to
one digit past the decimal (0.1 oC) Decomposition point: The temperature at which a solid f. For subsequent tests be sure to cool the apparatus to 10- decomposes. Some solids decompose rather than melt. 15C below the expected M.P. or you might see
spontaneous melting of your sample. Impure solid: melts at a lower temperature and over a wider g. If all samples have finished melting before the set stop range. Thus, a solid's melting point is useful not only as an aid temperature, you can end the test. in identification but also as an indication of purity. h. Never re-melt any sample. They might undergo oxidation, Suppose two compounds X and Y have identical melting points rearrangement, or decomposition. of 131- 132 oC and appear to be identical. i. Be sure to turn off and unplug the apparatus when
finished. Return all borrowed equipment. We can easily determine whether or not X and Y really are the j. Place all used capillaries in the glass receptacle, not the same compound by mixing a small amount of Y with X (or vice regular trash. versa) and taking the melting point of the mixture. (The melting point of a mixture is called the mixture melting point). If X and
9 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Procedure:
Part A: Determination of Melting Points unknown. Set the start temperature 10 oC lower than the approximate temperature and end Determine and record the M.P. data of one temperature 10 oC higher. The ramp rate needs sample each of; to be set at 2oC/min.
Capillary 1: urea 3. Compare the MP to those listed in table 2.1; pick Capillary 2: trans-cinnamic acid three compounds with a similar MP to test Capillary 3: 50-50 mixture of urea and trans- against. cinnamic acid. (Crush and mix well). 4. B.3: Prepare a 50:50 mixture of the unknown Set the start temp to 85 oC, ramp rate 2oC/min, with three known compounds with a similar MP and end temp 140 oC. Test all three of these to that of the unknown accurate MP. Test all capillaries at the same time. three capillary tubes at the same time. Be sure to indicate on the report sheet, which Part B: Identification of Unknown by Melting Point compound you mixed with the unknown for
1. Record the unknown number. B.1: Determine each capillary. the approximate MP of the unknown by taking a “fast ramp rate” MP. Set the start temperature 5. Record all data from all tests, and clearly identify to 85oC, the end temperature to 175oC and the the unknown. ramp rate to 10oC/min. (This is the only time the ramp rate will not be 2oC/min) 6. Disposal: Reagents in waste container. Glass in cardboard glass receptacle. 2. B.2: From the approximate MP determined, take an accurate “slow ramp rate” MP of the
Table 2.1
Compound MP oC Compound MP oC glutaric acid 97-99 benzoin 132-133 dibenzothiophene 99-100 trans-cinnamic acid 132-133 acetanilide 113-114 urea 132-133 (±)-mandelic acid 119-120 cholesterol 148-150 benzoic acid 121-122 salicylic acid 156-158 2-napthol 121-122 benzanilide 164-166
Helpful Hint: The conclusion for reports must include results of your experiment. Yes I know you have it in the data and report page, but it must also be included in the conclusion. Here is an example of what results are needed in this conclusion: In Part A, the MP range of urea was determined to be __-__oC and trans-cinnamic acid to be __-__oC. Comparing the literature value MP of urea & trans-cinnamic acid, the sample(s) is/are (pure/ impure). The melting point range of the 50-50 mixture is __-__oC and is lower and broader (?) due to it being a mixture. In Part B, unknown compound # ___ had a MP range of __-__oC, and the unknown is ______. Don’t forget to write sources of error as a separate bulleted section and clearly labeled. 10 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
REPORT Experiment 2: Melting Point Name:______
Record settings for MP apparatus, and the temperatures in oC at Onset and Clear Point
Part A: Determination of Melting Capillary 1 Capillary 2 Capillary 3 50:50 mixture Points Urea Trans-cinnamic acid Urea:Transcinnamic acid
Literature Melting Point Value Temp oC
Settings on MP Apparatus Onset Temp oC Start Temp oC
Clear (end) Ramp Rate oC/min Point Temp oC
MP Range oC End Temp oC (Onset – Clear)
Part B: Identification of Unknown by Melting Point: Unknown # ______
B.1: Approximate MP Fast Ramp Rate for Unknown B.2: Accurate MP Slow Ramp Rate For Unknown
Fast Ramp Rate Unknown Slow Ramp Rate Unknown Settings on MP Apparatus Temp oC Settings on MP Apparatus Temp oC
Start Temp oC Onset Start Temp oC Onset
Clear Ramp Rate oC/min Ramp Rate oC/min Clear Point Point MP End Temp oC End Temp oC MP Range Range
Capillary 1 Capillary 2 Capillary 3 B.3: MIXED MELTING POINTS 50:50 Unknown & 50:50 Unknown & 50:50 Unknown & Settings on MP Apparatus Temp oC
Start Temp oC Onset
Ramp Rate oC/min Clear Point
End Temp oC MP Range
Based on only sample color/texture, is this likely
the compound? (Yes or No)
Did sample melt Immediately? (Yes or No)
UNKNOWN # ______is determined to be ______based on the melting point range
11 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Questions: These are to be answered on this sheet only, not written in your lab notebook
2.1 Melting point determination can be used for several purposes. What are those Purposes?
2.2 What is the difference between the capillary melting point and the true melting point?
2.3 Two test tubes contain compounds where each melts at 148 – 150 oC. Using melting points, how could you determine whether the two test tubes contain the same or different compound?
2.4 Why would the rate of heating (ramp rate) influence the melting point?
2.5 a. Three test tubes contain organic solids labeled as X, Y, and Z, each melts at 149-150 oC. A 50-50 mixture of X and Y melts at 132-140 oC. A 50-50 mixture of X and Z melts at 149-150 oC. Are the solids X, Y, or Z the same or different as each other?
______& ______are the same compound, ______is different b. Predict what range a 50-50 mixture of Y and Z would melt. ______
2.6 In a recrystallization (a technique that you will encounter later in the semester), a solid is dissolved in a solvent and later the solvent is removed. If a MP of the sample is taken while the sample is still moist with solvent, what effect would that have on the MP of the sample?
12 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 3: Distillation Read and review chapters 4,5,6,8,18,19,20,34 in your OCHEM Survival Guide.
Caution: Hexane and toluene are flammable; DO NOT about one per second. Record the volume and USE BUNSEN BURNER AS A HEAT SOURCE; Use temperature when you have collected heating mantle for Macro Distillation, hot plate (Do 4,6,8,10,12,14,16 and 18 mL of distillate. Save the NOT set dial above 3-4) for Micro Distillation distillate and residue for Part C (Hickman Still). Record all temperatures to one digit Part C: Fractional Distillation of Mixture of Toluene past the decimal (0.1 oC). and Hexane Use one fresh boiling stone for each distillation. Assemble fractional distillation column (fig 19.10),
add glass beads to the column and attach it to the Macro Distillation: Parts A – C. Assemble the simple apparatus. Place the combined distillate and residue distillation apparatus (Fig 19.1) using a 50-mL round from Part B, along with an additional 10 mL of bottom flask for distilling, and a 25-mL graduated toluene and one boiling stone. Adjust the heat so cylinder as the collection vessel. Use 2 lab jacks for that the drops are at a rate of about one per each end, the end with the heating mantel (with second. Record the temperature when you have rheostat) will need enough room so that the lab jack collected 4,6,8,10,12,14,16, and 18 mL of distillate. can be lowered to allow the sample to be put directly into the round bottom flask, never pour liquid down Graph Temperature (oC) vs. Volume (mL) for each the adapter to get to the flask. Use Keck clips to distillation (Parts A, B, C) on the same graph, using connect the water condenser, and the two adapters different colors for each distillation. Turn in with together. Never use a Keck clip on a reaction flask. Be report. An example of a graph of the ideal conditions sure all joints are tight. Use utility clamps to secure it for fractional distillation is shown. The horizontal to the lab poles. The graduated cylinder must not fit lines on the graph represent the boiling point of snug, allow a small gap so the system is open to the hexane and toluene respectively. Boiling points are atmosphere. Start the water circulating through the reported as a single value, not a range as in melting condenser from bottom to top. points.
Part A: Simple Distillation of Hexane Place 15-mL of hexane in the flask, with one boiling stone. Be sure all joints are still tight. Get this checked by the instructor before proceeding. Start heating the flask and increase the heat gradually until the hexane boils. When the liquid begins to drip into the graduated cylinder, adjust the heat so that the drops are at a rate of about one per Part D: Microscale Distillation of 2.0 mL Hexane second. Record the volume and temperature when (This can be set up and started at the same time as Part C.) you collect 3,5,7,9, 11 and 13 mL of distillate. The temperatures you have recorded should not vary Assemble the Hickman Still (fig 20.1 on left), using a more than 2 oC and represent the boiling point range 4-mL conical vial with one boiling stone (not spinner) of hexane. Use the distilled hexane for Part B. and add condenser to top. Don’t use a cap on the Hickman still. You may use foil on the sand bath to Part B: Simple Distillation of Mixture of Toluene and help maintain temperature. DO NOT set dial on hot Hexane plate above 3-4. Use a syringe to withdraw the liquid Use the same apparatus as in Part A to distill 10 mL collected in the collar. Measure and record volume of hexane and 10 mL toluene (add one boiling stone). and temperature at approximately 0.1 mL intervals. Adjust the heat so that the drops are at a rate of Rinse all glassware with acetone before returning.
13 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
REPORT Experiment 3: Distillation Name:______
Part A: Simple Distillation of Hexane Qty. Distilled in mL 3 5 7 9 11 13 15
Temperature oC
Part B: Simple Distillation of a Mixture of Toluene and Hexane Qty. Distilled in mL 4 6 8 10 12 14 16 18 20
Temperature oC
Part C: Fractional Distillation of a Mixture of Toluene and Hexane Qty. Distilled in mL 4 6 8 10 12 14 16 18 20
Temperature oC
Part D: Microscale Distillation of Hexane Qty. Distilled in mL
Temperature oC
Questions: Graph data before answering questions, you will use the graph for some questions.
3.1. From the distillation graphs, what is the boiling point of hexane and toluene for each distillation? Take an “average” of horizontal line of the data. Note that boiling points are reported as a single value, not a range as in melting points. Be sure to compare and evaluate the experimental BP to the literature BP value in the conclusion of the report. Literature Boiling Point Part A: Simple Distillation Part B: Simple Distillation Part C: Fractional
(Look this up) of Hexane of Mixture Distillation of Mixture Hexane
Toluene
3.2. From the distillation graphs, what volume of liquid boiled below 85C without and with a fractional distillation column (Part B & C)?
Simple ______mL Fractional ______mL ___ 3.3. From your experimental results, which procedure is more efficient to separate the mixtures, simple distillation or fractional distillation (Part B & C)? (Circle answer)
Simple distillation Fractional distillation
3.4. Why is it dangerous to heat a liquid in a distillation apparatus that is closes tightly at very joint and has no vent to the atmosphere?
3.5. Why is it important for the water to enter the condenser jacket at the lower end?
14 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 4: Recrystallization --READ CHAPTERS 13 & 14 in your OCHEM Survival Guide Recrystallizing Acetanilide with Hot Gravity Filtration & Buchner Filtration
Recrystallization is a technique used to purify products flask in a sand bath on a hot plate. (Sand after synthesis. It can also be used to purify “dirty” bath is sand in a metal pan about ¼ to ½ full samples. Your sample will look like it came from a then use sand to surround flask). dustpan, contaminated with impurities. You will attempt 11. Pour the acetanilide solution in small to separate and purify it through recrystallization. You will batches through the filtration system, the evaluate the success of your efforts by determining purity of product from the melting point of your recrystallized solution should be colorless. If not, repeat sample, and additionally calculate the % recovery. Be sure from step 6, using activated charcoal again. to weigh the filter paper used in the last step before you 12. When filtration is complete, boil off 2-3 mL use it so you can get a more accurate result. of the excess solvent added. Remove from heat, cover the flask with a small watch glass, and allow to cool. Procedure: Use analytical balance for all masses.
1. Add 100 mL water to a 125-mL Erlenmeyer Recrystallization of Crude Product flask and heat to boiling on a hot plate. DO 13. When the flask is at room temperature, NOT set dial on hot plate past 3-4. place in an ice bath for 5 – 10 minutes to 2. Weigh 500 mg of crude acetanilide and place ensure complete crystallization. (If oil forms, in a 50-mL Erlenmeyer flask along with a add a little water, heat to boiling, cool) boiling chip. 14. If recrystallization does not occur, scratch 3. Add approximately 5 mL hot water to the the inside of the flask with a glass rod. (Or, acetanilide and swirl. Slowly heat on the hot you may still have too much solvent and plate to boiling. need to boil off a little more). 4. Continue to heat and add small aliquots (about 1mL) of hot water (swirl at each Büchner Filtration addition) until all acetanilide dissolves. 15. When the flask with your purified product is 5. If the solution is colored, it contains cold and crystallization is complete, suction impurities and it is necessary to do a hot filter the crystal a using a Buchner funnel. gravity filtration with activated charcoal. Since this is a cold filtration, you need to 6. Remove flask from heat and cool to just prepare the Buchner funnel by making it below the BP (or it will splatter when the cold. After it is set up, (fig 13.5) and filter charcoal is added). paper is in and ready to go, you need to run 7. Add a spatula tip full of activated charcoal to ice cold water through to ensure the inside is remove color. Do not add more than cold. (Did you weigh the filter paper?) necessary. 16. Transfer the crystals to the funnel; you may 8. Add an additional 1-2 mL hot water to the need to wash-out with minimal ice cold flask, and heat to boiling point. water. Wash the crystals in the funnel with small portions of ice cold water. Hot Gravity Filtration 17. Air-dry the crystals. When completely dry, 9. Set up a 25-mL Erlenmeyer flask containing a record the weight and melting point. boiling chip with a stemless funnel and 18. Calculate percent recovery. (Reminder: You fluted filter paper. (Fig 13.3) must show all calculations in lab notebook, 10. Pour 1-2 mL hot water through the funnel to turn in with report next week, and no credit fill the flask with solvent vapors, and put the if turned in with data page).
15 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
REPORT Experiment 4: Recrystallization Name: ______
Literature Melting Point Value for Acetanilide Mass of Crude Acetanilide Mass of Purified Acetanilide + Filter Paper Mass of Filter Paper Mass of Purified Acetanilide Percent Purified Acetanilide Recovered from Crude Sample (Show Calculation in Notebook. Be sure to report this in the conclusion.) Experimental M.P. Range of Purified Acetanilide (Note: Be sure to include in conclusion, both the literature MP value and the experimental value. By comparing the MP values, determine and report the purity of the product using MP.)
Questions:
4.1 What is activated charcoal, and what happens if you use too much?
4.2 Why was a stemless funnel used in gravity filtration?
4.3 What problems may occur if crystallization occurs too rapidly?
4.4 Why should recrystallization mixture be cooled in an ice bath prior to filtering?
4.5 Even after cooling, sometimes crystallization doesn’t occur. Explain at least three ways to induce crystallization.
4.6 Why is it important to cool the Buchner funnel before filtration? Why wash the precipitate in the funnel with ice cold water?
16 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 5: Sublimation & Extraction READ CHAPTERS 10,11,15,16,23,24, 35 in your OCHEM Survival Guide Dry lab, this will be completed in lab. A complete lab report is still required such as notebook and report.
Part A: Sublimation of Caffeine (You may start Part B while waiting for sublimation to occur). 3. Pour solution into a 125 mL separatory funnel that is supported in a ring stand. Make sure the stopcock is closed before you add solution.
1. Weigh and record the mass of 500 mg impure 4. Pipet 10.0 mL methylene chloride into the caffeine. Erlenmeyer flask; swirl, then add contents to the fig. 24.1 2. Assemble the sublimation apparatus ( separatory funnel. Stopper the funnel. “inexpensive” on right. Be sure to add ice.) 5. Partially invert the funnel and open the stopcock
3. Put the impure caffeine sample in the bottom of to vent and release the pressure. Close the the flask and clamp in place, in a sand bath, on a stopcock, swirl the funnel gently several times, hot plate. invert, and vent again. Repeat several times.
4. Pull a vacuum while heating gently. As the 6. Replace the funnel in the ring and allow the sample is heated, crystals will form on the cold layers to separate. finger. You may need to remove melted H2O and 7. Remove the stopper and open the stopcock to add more ice. drain the lower methylene layer into a clean 25-
5. Continue heating until no more crystals form on mL Erlenmeyer flask. Don’t dispose of the the cold finger. Remove from heat and allow aqueous layer until experiment is finished. cooling to room temperature. 8. Extract the caffeine a second time to remove any
6. Cautiously break the vacuum, and carefully remaining in the aqueous layer. Repeat from step remove the cold finger. 4 with a second 10.0 mL portion of methylene
7. Scrape the crystals onto a pre-weighed paper, chloride. Collect the two organic layers into the reweigh, and record mass of pure caffeine. same flask (Step 7).
8. Calculate % recovery. 9. Use spatula to add anhydrous sodium sulfate to the combined methylene chloride solution in the Part B: Extraction of Caffeine to Determine flask and swirl. Continue adding small amounts of Distribution Coefficient drying agent until no further clumping occurs, and some of the drying agent is free flowing. Do not breathe methylene chloride vapors. Work in 10. Stopper the flask with a cork and let stand for 5 hood. minutes.
1. Weigh and record the mass of 300 mg of pure 11. Gravity filter the dried solution, into pre- caffeine, put in a 25-mL Erlenmeyer flask. weighed*, dry 50-mL Erlenmeyer flask that 2. Pipet 10.0 mL water into the flask, swirl to contains a boiling chip. *(Weigh flask with boiling chip in it) dissolve caffeine. Some crystals may remain, add 12. Rinse the drying agent with a fresh portion methylene chloride or crush crystals to help (about 1-2 mL) of methylene chloride and add to dissolve. the same flask. 13. Place the flask in a warm sand bath. Evaporate the solvent under the hood. Reweigh the flask. Distribution coefficient: If KD is: > 1 prefers organic layer, = 1 prefers both the same, < 1 prefers aqueous layer
퐒퐨퐥퐮퐛퐢퐥퐢퐭퐲 퐢퐧 퐨퐫퐠퐚퐧퐢퐜 (퐠/ퟏퟎퟎ 퐦퐋) 퐠 퐜퐚퐟퐟퐞퐢퐧퐞 퐢퐧 퐦퐞퐭퐡퐲퐥퐞퐧퐞 퐜퐡퐥퐨퐫퐢퐝퐞 퐾 = = 퐷 퐒퐨퐥퐮퐛퐢퐥퐢퐭퐲 퐢퐧 퐰퐚퐭퐞퐫 (퐠/ퟏퟎퟎ 퐦퐋) 퐠 퐜퐚퐟퐟퐞퐢퐧퐞 퐢퐧 퐇ퟐ퐎
17 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
REPORT Experiment 5: Sublimation & Extraction Name:______(Be sure to include a data page in your notebook) Part A: Sublimation of Caffeine Mass of impure Caffeine ______0.502 ______g
Mass of pure Caffeine + Filter Paper ______0.491______g
Mass of Filter Paper ______0.390______g
Mass of pure Caffeine ______g
Percent pure Caffeine recovered ______%
Part B: Extraction of Caffeine Mass of pure Caffeine ______0.300 ______g
Mass of dry 25-mL Erlenmeyer flask ______21.294______g
Mass of flask+ Caffeine in methylene chloride ______21.485 ______g
Mass of Caffeine in methylene chloride ______g
Questions: Show all calculations in lab notebook.
5.1 Calculate the mass of caffeine remaining in the water from Part B. (The mass of caffeine will be the difference between the starting mass of caffeine and the mass of caffeine in methylene chloride)
______g
5.2 Calculate the distribution coefficient of caffeine in the methylene chloride/water system form Part B. KD = ______
5.3 Based on KD, indicate the preference of caffeine, either organic solvent, aqueous or both. Explain.
5.4 List 5 typical drying agents.
18 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 6: Molecular Models Notes & Templates
Do not wait until the last minute to do this experiment, it takes a lot of time to complete. You will not write a purpose or conclusion for this experiment, fill in the report sheets completely and that is what you will turn in for grading. You may need to use other reference sources, (text, lecture notes, internet, etc.).
6.5 TEMPLATES: Sight down the carbon-carbon bond and slowly rotate one carbon with respect to the other. There is free rotation around a single bond. Several conventions, dashed wedge-solid wedge, sawhorse, and Newman can represent these conformations.
Dashed Wedge & Solid Wedge Sawhorse Newman Projection Staggered Eclipsed Staggered Eclipsed Staggered Eclipsed
CH CHH 3 6.8 Newman Projections and energy H 3 H graph for butane (n-butane) A Eclipsed H
H H CH CH H 3 H 3 A A H H B Gauche C C H H H CH H 3 E H B E C Eclipsed CH H 3 D HH CH H H 3 0 60 120 180 240 300 360 H D Anti H Degrees of Rotation
H CH H 3 H CH H 3 E Gauche CH H H 3
H H
6.15 TEMPLATES: for cyclohexane Chair Boat Newman Newman
19 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
20 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Name: ______Lab day/time ______/ ______
6. 1 Build the models for the following methane compounds and complete the table. Molecular Formula CH4 CH3Cl CH2Cl2 CHCl3 CCl4
Expanded Structural Formula
IUPAC Name
Polar or Non-polar What is the bond angle? What is the geometry (VSEPR) shape? What is the hybridization? All of these methane compounds have the same bond angle, geometry and hybridization around the carbon
6.2 Complete the following reactions for the following methane compounds: The combustion reaction of methane (Show reaction using molecular formula)
The bromination reaction of chloromethane (Show reaction using structural formula)
6.3 Complete the following table: Draw the expanded structural formula for Which of the following compounds Which of the following compounds bromomethane, Indicate the polarity and dipole are saturated: Circle answer(s) are unsaturated: Circle answer(s) moment on the appropriate atoms
Alkane Alkene Alkane Alkene
Cycloalkane Alkyne Cycloalkane Alkyne
21 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
6. 4 Build the models for the following ethane compounds and complete the table. Molecular Formula C2H6 C2H5Br C2H4Br2 (2 isomers exist, draw and name each)
Condensed
Structural Formula
IUPAC Name
Polar or Non-polar
6.5 For ethane C2H6, draw the following conformations, be sure to draw the all six hydrogens on each structure (See Experiment Notes for templates) Dashed & Solid Wedge Sawhorse Newman Projection
Staggered (Lower energy so more stable conformation)
Eclipsed (Higher energy so less stable conformation)
6.6 Complete the following reactions for the following ethane compounds: The combustion reaction of ethane (Show reaction using molecular formula)
The chloronation reaction of ethane (Show reaction using structural formula)
22 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
6.7 The molecular formula C4H10 has two structural isomers, build models of each, and draw and name the structure of each isomer. Molecular formula C4H10 C4H10
Condensed Structural Formula
IUPAC name
What is the bond angle What is the geometry Are the Molecules around each carbon? (VSEPR) shape? Water soluble?
6.8 For butane (n-butane) build the model and sight along the C-2 & C-3 bond. Draw the 5 possible Newman Projection conformations. (See Experiment Notes) A Eclipsed B Gauche C Eclipsed D Anti E Gauche Highest Energy (Least stable) Energy Cost Energy Cost Lowest Energy (Most stable) Energy Cost Energy Cost Energy Cost kJ/mol kJ/mol kJ/mol kJ/mol kJ/mol
6.9 Complete the following reactions for the following compounds: The combustion reaction of butane (Show reaction using molecular formula)
The bromination reaction of butane, you will get two
substitution products. (Show reaction using structural formula)
23 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
6.10 Build the model for C2H4 and complete the following table. Molecular Formula C2H4 Is this molecule saturated or unsaturated? DOU? Is there free rotation around the double bond?
Condensed Structural
Formula (You must show
all double bonds) What is the bond angle around the carbon? What is the hybridization around the carbon?
What is the Geometry (VSPER) shape around the What is the carbon type (1o, 2o, 3o, 4o)? IUPAC Name carbon?
6.11 Complete the following reactions for the alkene compounds: (Show reactions using structural formula)
Write the addition reaction for the
hydrogenation of ethene
Write the addition reaction for the
bromination of propene
Write the addition reaction of HBr to
1-butene
Write the hydration reaction of 2-methylpropene and water
6.12 Build the models for the three isomers of C2H2Cl2 and complete the following table. Molecular Formula C2H2Cl2 C2H2Cl2 C2H2Cl2
Expanded Structural Formula (Show 120o bond angle, be sure to show double bond)
IUPAC Name
24 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
6.13 Build the six isomers of C4H8 (Note the DOU for this formula), four will have one double bond, and two will have one ring and no double bonds. Complete the table. IMPORTANT NOTE: For 2-butene: Draw only the cis & trans isomers, showing the 120o bond angle to illustrate the correct geometry
Condensed Structural Formula
IUPAC Name
Condensed Structural Formula
IUPAC Name
6.14 Draw either the condensed structural formula or the line structure for the following cyclic alkanes, all these compounds are unsaturated with one DOU. cyclopropane cyclobutane cyclopentane cyclohexane
25 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
6.15 Cyclohexane (C6H12). The ring can have two different conformations, the chair (more stable) and the boat (less stable). (See Notes for templates) Chair Conformation (Be sure to label axial Newman Projection of Chair (Be sure to Boat Conformation (Be sure to include all Newman Projection of Boat (Be sure to & equatorial hydrogens) include all hydrogens) hydrogens, there are no axial or equatorial include all hydrogens) hydrogens on a boat)
6.16 Build the alkyne C2H2 and complete the following table: Molecular Formula C2H2 Is this molecule saturated or unsaturated? DOU? Is there free rotation around the triple bond?
Condensed Structural Formula (You must show all triple bonds) What is the bond angle around the carbon? What is the hybridization around the carbon?
What is the Geometry (VSPER) shape around the What is the carbon type (1o, 2o, 3o, 4o)? IUPAC Name carbon?
6.17 Complete the following reactions: Write the combustion reaction for ethyne (Show reaction using molecular formula)
Write the addition reaction for the hydrogenation of ethyne (Show reaction using structural formula)
26 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 7: Chromatography -- READ CHAPTERS 26-28, 30-31 in your OCHEM Survival Guide
Chromatography is a technique used to separate The sample is the matter analyzed in components of a mixture. The discovery of paper chromatography. It may consist of a single chromatography in 1943 by Martin and Synge component or it may be a mixture of components. provided for the first time the means of surveying The solute refers to the sample components in constituents of plants and for their separation and partition chromatography. identification. It was originally used to separate a The solvent refers to any substance capable of solubilizing another substance, and especially the mixture of colors, but is it now also used to liquid mobile phase in liquid chromatography. separate colorless mixtures using more advanced The stationary phase is the substance fixed in place techniques. for the chromatography procedure. Examples This experiment will explore two types of include the paper for paper chromatography, and chromatography separations, partition (paper) and the slurry layer in column chromatography. adsorption (column). The mixture is dissolved in a fluid called the mobile phase, which carries it Part A: Paper Chromatography: Separation of through a structure holding another material Colors in Food called the stationary phase. The various Coloring constituents of the mixture travel at different speeds, causing them to separate. The separation Set up Part A, is based on differential partitioning between the complete Part B mobile and stationary phases. while waiting for colors to separate Paper chromatography is a technique that involves in Part A. Figure 7.1 placing a small dot or line of sample solution onto a strip of chromatography paper. The paper is Paper chromatography is a form of partition, the placed in a jar containing a shallow layer of solvent filter paper and the adsorbed water act as the and sealed. As the solvent travels through the stationary phase, and the solvent is the mobile paper, it meets the sample mixture, which starts phase. The chromatogram is recorded in terms of to travel through the paper with the solvent. a number called the Rf value, which is a ratio of Column chromatography is a separation technique the flow of color to solvent. in which the stationary bed is within a tube. The particles of the solid stationary phase or the 푑푖푠푡푎푛푐푒(푐푚) 푐표푙표푟 푡푟푎푣푒푙푒푑 푓푟표푚 푐푒푛푡푒푟 푅푓 = support coated with a liquid stationary phase may 푑푖푠푡푎푛푐푒(푐푚) 푠표푙푣푒푛푡 푡푟푎푣푒푙푒푑 푓푟표푚 푐푒푛푡푒푟 fill the whole inside volume of the tube (packed Procedure: column). 1. Fold a piece of 12.5-cm filter paper in half and in half again to find the center. Use this sheet as a guide Key Terms: to punch a hole through the center of four additional Chromatography is a physical method of sheets of similar but unfolded filter paper, use a copper separation that distributes components to separate wire for making hole. The center hole should be about between two phases, one stationary (stationary 1.5-mm in diameter. phase), while the other (the mobile phase) moves in a definite direction. 2. Use a toothpick to make a spot of food color The eluate is the mobile phase leaving the column. on each filter paper about 5-mm in the center. Add a The eluent is the solvent that carries the analyte. drop of yellow food coloring at the center of one filter The mobile phase is the phase that moves in a paper, a drop of blue food coloring at the center of a definite direction. It may be a liquid, or a gas. The second, a drop of green food coloring to the third, and mobile phase consists of the sample being a 50/50 mixture of blue and yellow food color to a separated/analyzed and the solvent that moves the fourth. (Prepare the 50/50 mixture by mixing these sample through the column or paper colors on a watch glass well before applying the spot). 27 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
With pencil, lightly write the color used on each filter 2. Set up a clean filter flask with a one-hole paper on the outer edge. rubber stopper and attach it to the vacuum. 3. Add solvent, 2:1 n-propyl alcohol: water 3. Set up the column by using a disposable (already prepared) to each of the bottom halves of four Pasture pipet (fig. 7.2). Add a small piece of cotton, to half-full, approximately 30 mL each. This solvent will rolled into a ball, to the column, and push it down using be reclaimed in a labeled container after the a copper wire. Add 1 – 2-mm high of sand to the experiment; do not dump this down the drain. column. 4. Prepare the filter paper wicks by tightly rolling 4. The adsorbent has been pre-measured for you, a 1 x 2-cm strip of filter paper into wicks the you need to add it to a 50-mL beaker and add approx. appropriate length for the Petri dish. The wick should 40-mL of 95% ethanol to make slurry. Once the touch the bottom, but not the top, trim paper if adsorbent is wet, do not allow it to become dry at any necessary. Insert the wicks into the filter paper with the point in the experiment. color already applied. 5. Insert the column into the one-hole stopper. 6. Rest the sheets of filter paper on the rims of Use a small pipet to transfer the slurry into the column, the Petri dishes (fig. 7.1) with the longer part of the and apply a gentle suction. Fill the column up to the wick extending into the solvent. Cover the papers with indention of the column, which is about 2-cm the larger halves of the Petri dish and allow developing, from the top. Turn off the vacuum, and be Figure 7.2 this may take 30-60 minutes. It is finished when the sure there is liquid always above the level of solvent front is almost to the edge of the paper. the adsorbent. (It can be all the way to the top.) Immediately mark the solvent front with a pencil as it 6. Have dye ready in a dropper, and when dries quickly. the level of the liquid above the slurry is about 7. Carefully remove the wicks and allow the 1-mm high, add enough dye to fill to the top. chromatograms to dry. 7. Keep adding eluent, (95% ethanol from 8. Measure the distance from the center of the the small test tube) to the column to keep the filter paper to the center of each of the color(s) and level of the liquid at no less than 2-mm above also the distance from the center to the solvent front. the slurry. Continue to add until all of the blue Record on report to one digit past decimal. dye has passed down the column. The yellow dye will remain on the column. 9. Calculate the Rf value for all of the pigments (red, yellow, & blue) separated for each of the 8. Remember to not let the level of the chromatograms. Show a sample calculation on report. liquid in the column get lower than less than 2- mm above the slurry at any time. Transfer the Part B: Column Chromatography: Separation of Two blue eluent in the flask to a test tube. Rinse out Dyes the flask put the column back on the flask. (Complete Part B while you are waiting for the colors to 9. Now add distilled water to the column separate in Part A.) with a dropper to keep the level of the liquid at Procedure: no less than 2-mm above the slurry. Continue to add until all of the yellow dye has passed down the column. 1. Obtain about 1-mL (1-cm high) of green dye Transfer the yellow eluent in the flask to a test tube. mixture (not food coloring) in a small test tube, and Show each color sample to the instructor to initial about 8-mL of 95 % ethanol in a separate small test report. tube.
28 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Report Experiment7: Chromatography Name: ______
Part A: Paper Chromatography: Separation of Colors in Food Coloring Record Distance Traveled in cm for each color separated one digit past decimal, 0.1 cm. Mark an X in the data box if that color was not found.
Test Solvent Yellow Blue Red 1. Yellow food color
2. Blue food color
3. Green food color
4. 50/50 Blue/Yellow Food color
Part B: Column Chromatography: Separation of Two Dyes
Separated Colors Instructor’s Initials Blue Dye Yellow Dye
Calculations and Questions:
7.1 Calculate the Rfvalue for each color that was separated in Part A. Mark an X in the data box if that color was not found. Show sample calculation in notebook
푑푖푠푡푎푛푐푒(푐푚) 푐표푙표푟 푡푟푎푣푒푙푒푑 푓푟표푚 푐푒푛푡푒푟 푅푓 = 푑푖푠푡푎푛푐푒(푐푚) 푠표푙푣푒푛푡 푡푟푎푣푒푙푒푑 푓푟표푚 푐푒푛푡푒푟
RF Values Yellow Blue Red 1. Yellow food color
2. Blue food color
3. Green food color
4. 50/50 Blue/Yellow Food color
7.2 What do you notice about the Rf value of each ring of color for every test?
7.3 Predict what would have happened if the solvent 2:1 n-propyl alcohol:water (intended for Part A) was used instead of 95 % ethanol required for the initial separation in Part B.
29 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
30 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
FORMAL LAB WRITE-UP FORMAT Formal lab report on either exp. 2,3,4,7 (20 points) See Syllabus for Due Date
Please use the following format. The report must be typed and presented in a folder with a cover page.
HOW TO WRITE A LABORATORY REPORT
Being able to write a coherent account of an event is important for people working in any field. Laboratory reports should be considered as much an exercise in this skill as are English essays and History term papers. While great eloquence in any style is not crucial, clarity and conciseness are essential.
A lab report indicates several things: how well you can design, describe, and carry out an experiment, how well you understood what you did in lab, how methodically and logically you can present your results and conclusions, and whether you have thought carefully about your results and consulted references which will help you interpret them.
In addition to clarity and thoroughness, aim for good grammar, correct spelling, and proper sentence structure when you write lab reports. Try to write using impersonal prose. The proper tense to use depends on the topic and takes practice to master. Never mix tenses!
Define all symbols and abbreviations that you use.
Mathematical symbols must be displayed properly. Example: The proper way to use scientific notation is with superscripts -- e.g., 6.02 x 10-4, not 6.02E-04 or 6.02 x 10^-4. You can, of course, write the decimal equivalent (0.000602 in this case) instead.
Chemical formulas must contain the proper subscripted quantities -- water is H2O, not H2O.
Do not use quotations or otherwise copy from other sources (including the Manual or course textbook). Reports must be in your own words.
FORMAT OF A LAB REPORT
Objective/Purpose This section should indicate clearly what ideas are being investigated and state specifically what the purpose of your experiment is. If you do several experiments in one lab, the purpose of each should be given. Do not merely copy what is in the lab manual. Present the purpose in your own words. For many experimental labs, you should frame a hypothesis that you intend to test. Ideally, this section should be written before you start the lab.
Materials This section should specify what instruments, measuring devices, and other equipment you used during the lab. You do not need to include such obvious things as a pen, paper, or calculator. Include Illustrations/pictures of lab set-up and equipment.
Procedure This section describes the step-by-step process you used in the lab. You do not need to go into excruciating detail, but the methods you used in the lab should be clear to someone reading this section. Imagine that someone familiar with the topics you are investigating, but ignorant of the specifics of your experiment, is going to read your write-up. This section should contain enough detail so that this imagined reader could set up the lab, replicate the experiment, and obtain the same results. Remember, overly detailed descriptions are just as bad as those lacking details. For example, you do not need to go into detail describing how to set up the funnel and how to fold the filter paper to filter something. It is assumed that the reader will know how to use the funnel and filter paper.
31 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Data and Calculations The first part of this section should include all data tables and measurements taken. All data should be clearly labeled and all units should be noted. The second part of this section should include all calculations made and any graphs. Where appropriate, the percent error should also be stated. Do not try to interpret you data in this section, but do state in words what each graph, table, or other data presentation shows, and what are the main patterns present in the data.
Discussion/Conclusions This section includes an interpretation of your results and a discussion of what these results mean. Given the purpose and hypothesis you stated in your "objective" section, are your results expected? Did your data support your hypothesis? Why or why not? If something did not turn out the way you would have expected, discuss what may have accounted for the discrepancy. Do you see and errors that you made? Could the experimental design be improved? You may also want to discuss your results in comparison to other lab groups, or in comparison to past research found in your text or research journals. Any follow-up questions specific to a particular lab should be answered in this section.
References In scientific reports, footnotes are not typically used. Instead, books or articles that are used are referred to in the following manner: "Plasmids typically take up 10% of recombined DNA (Street and Opik, 1989, p. 18)." This type of statement might appear in you discussion section as you explain the meaning of your results. At the end of your lab report, you give the full reference to the book or article, and if you used more than one, you give them in alphabetical order by the first author’s last name. Suppose you had used the book above (by H.E. Street and H. Opik) and another by N. Campbell. At the end of your report, you would list the following under the heading "References".
Campbell, Neil. Biology (4th ed.). Redwood City, CA: Benjamin-Cummings, 1996.
Street, H.E. &Opik, H. Plasmid Genetics. New York: Oxford University Press, 1989.
If you use an article from a journal, the proper format would be similar to the above when you refer to it in the text, and in the references at the end you would state them as follows:
Day, S. & Night, D. "High-efficiency Photosynthesis in Angiosperms." Scientific American, 229 (1987), pp. 124 - 137.
If an Internet reference is used, include the complete address for that website.
NO LATE LAB REPORTS ACCEPTED Technological problems (printer, computer, disks, etc.) are not acceptable excuses for late reports or papers, so start early.
32 Copyright ® 2018 Kelly Boebinger
General Organic Chemistry I Laboratory CHEM 212
Experiment 8: Spectroscopy Labs (all due before 7:20 am): READ CHAPTERS 32 & 33 in your OCHEM Survival Guide
Typed Research Paper on IR and MS (20 points) Wed. Nov 14th Typed Research Paper on NMR and UV-VIS (20 points) Wed. Nov 28th McMurry Chapter problems and exercises (20 points) Mon. Dec. 3rd
NO LATE REPORTS OR PROBLEM SETS ACCEPTED Technological problems (printer, computer, disks, etc.) are not acceptable excuses for late reports or papers, so start early.
Requirements for Spectroscopy Research Paper: . The report must be typed and presented in a folder with a cover page. You are demonstrating your understanding of the material through what you present in your paper. You will be graded based on how I interpret your understanding of spectroscopy from your paper. . You must reference your sources and give proper credit. Do not plagiarize anyone else’s work. For example, you must cite the lab notes if you used them.
Research Papers must include detailed: 1. Background . Principles . Theory . Explanation of how and why it is used. 2. Instrumentation: . An illustration or picture. . Explanation on how instrument is used. . Explanation of how samples prepared, analyzed. 3. Spectra: . Clearly indicate what information can be obtained from the spectra. . Give sample spectra. . Examples of how to interpret spectrum. Write on the spectrum to show me how you read the information. 4. References and Resources. (You may not include dictionary web sites such as Wikipedia as a source).
Problem Sets from McMurry (5thed) Lecture Text--- Chapters 12, 13, 14 Show work or reasoning on all problems. Include photocopied spectra and label major fragments or functional groups on all spectra.
Chapter 12: Structure Determination: Mass Spectrometry and Infrared Spectroscopy
Problems: 1, 3, 4, 5, 9, 10, 11, 12, 13
Chapter 13: Structure Determination: Nuclear Magnetic Spectroscopy
Problems: 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 18, 19, 20, 22
Chapter 14: Structure Determination: Conjugated Dienes and Ultraviolet Spectroscopy
Problems: 1, 2, 6, 7, 9, 10, 11, 12
33 Copyright ® 2018 Kelly Boebinger