Stoichiometry • Mole Ratio

Total Page：16

File Type：pdf, Size：1020Kb

Honors Chemistry 2st Grading Period Competency Academic Vocabulary: Power Objectives: • stoichiometry • mole ratio • Articulate elemental and molecular properties utilizing physical • limiting reactant structures of the atom and the periodic table. (P.O. #1) • excess reactant • Characterize interactions between matter and energy. (P.O. #2) • theoretical yield • Demonstrate how mathematics describes concepts in • actual yield chemistry. (P.O. #3) • percent yield • Design and conduct chemistry investigations. (P.O. #4) Stoichiometry Enduring Understandings: Essential Questions: • Often in science, there is a difference between what could • Which relationships can be derived from a balanced chemical theoretically happen and what may actually happen. equation? • Chemical reactions are controlled by the unique properties of • How are mole ratios written from a balanced chemical equation? the reactants. • What is the sequence of steps used in solving stoichiometric problems? • Sometimes not all of the reactants are used up in a reaction, yet • How are these steps applied to solve stoichiometric problems? mass is always conserved. • In a chemical reaction, which reactant is the limiting reactant? • Stoichiometry is an analytical tool which combines the mole • How much of the excess reactant remains after the reaction is concept, mass and chemical conversions, and balanced complete? chemical equations. The pharmaceutical industry would not • How do you calculate the mass of a product when the amounts of more exist if it weren’t for the use of stoichiometry. than one reactant are given? • What is the theoretical yield of a chemical reaction? • How do you calculate the percent yield for a chemical reaction? .

Copy Link

Recommended publications

Types of Chemical Reactions and Solution Stoichiometry
Types of Chemical Reactions 4 and Solution Stoichiometry Contents 4.1 Water, the Common Solvent 4.2 The Nature of Aqueous Solutions: Strong and Weak Electrolytes • Strong Electrolytes • Weak Electrolytes • Nonelectrolytes 4.3 The Composition of Solutions • Dilution 4.4 Types of Chemical Reactions 4.5 Precipitation Reactions 4.6 Describing Reactions in Solution 4.7 Stoichiometry of Precipitation Reactions 4.8 Acid–Base Reactions • Acid–Base Titrations 4.9 Oxidation–Reduction Reactions • Oxidation States • The Characteristics of Oxidation–Reduction Reactions 4.10 Balancing Oxidation– Reduction Equations • The Half-Reaction Method for Balancing Oxidation–Reduction Reactions in Aqueous Solutions Yellow lead(II) iodide is produced when lead(II) nitrate is mixed with potassium iodide. 126 Much of the chemistry that affects each of us occurs among substances dissolved in water. For example, virtually all the chemistry that makes life possible occurs in an aqueous environment. Also, various medical tests involve aqueous reactions, depending heavily on analyses of blood and other body ﬂuids. In addition to the common tests for sugar, cholesterol, and iron, analyses for speciﬁc chemical markers allow detection of many diseases before obvious symptoms occur. Aqueous chemistry is also important in our environment. In recent years, contami- nation of the groundwater by substances such as chloroform and nitrates has been widely publicized. Water is essential for life, and the maintenance of an ample supply of clean water is crucial to all civilization. To understand the chemistry that occurs in such diverse places as the human body, the atmosphere, the groundwater, the oceans, the local water treatment plant, your hair as you shampoo it, and so on, we must understand how substances dissolved in water react with each other.
[Show full text]
Chapter 17: Electrochemistry
4/12/2021 17.1 Electrochemistry Chapter 17: Deals with chemical reactions that produce electricity and the changes associated Electrochemistry with the passage of charge through matter. Reactions involve electron transfer – oxidation/reduction (redox) Example: A typical AA alkaline battery is rated at 1.5 V. This means the electrical potential difference between the +/– terminals is 1.5 V. It is the chemical reactions in the battery that give rise to this difference. 1 2 1 2 Redox Recap Assigning oxidation numbers Oxidation number rules: 1.) Ox. # = 0 for an atom in pure, elemental state 2+ 2.) Ox. # = <charge> for monatomic ion: Ox. # = 2 for Ca Oxidation number: +1 –1 3.) Sum of all Ox. #’s for atoms in polyatomic ion = charge on polyatomic ion Total contribution to charge: +2 –2 = 0 4.) Sum of all Ox. #’s = charge on species: H2O Ox.(H) = 1, Ox(O) = –2 Oxidation number: +1 +6 –2 Total contribution to charge: +2 +6 –8 = 0 3 4 3 4 1 4/12/2021 Redox terminology Redox terminology applied Oxidation – the loss of electrons OIL RIG – “oxidation is losing, Reduction – the gain of electrons reduction is gaining” 0 +2 –1 +2 –1 0 “Substance X undergoes oxidation.” – X lost electrons 0 +2 –2 +2 –2 0 “Substance Y was reduced.” – Y gained electrons Oxidizing agent – the species that undergoes reduction What was oxidized? Zn Oxidizing agent = CuCl2 Reducing agent – the species that undergoes oxidation What was reduced? Cu2+ Reducing agent = Zn “Substance Z is the oxidizing agent.” – Z gains electrons What is the spectator ion? Cl– (Think: Travel agent – allows someone else to travel) 5 6 5 6 17.1 Balancing redox reactions Example: Balancing redox reaction in acidic solution 1.) Assign oxidation states to all atoms.
[Show full text]
Gas Stoichiometry 84 Mins
Chemistry 20 Unit 4 Lesson 3 - Gas Stoichiometry 84 mins Gas Stoichiometry - gas volume, pressure and temperature, molar If 275 g of propane burns in a gas barbecue, what volume, and the ideal gas law volume of oxygen measured at STP is required for the reaction? PV = nRT C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) 760.000 mmHg = 101.325 kPa = 1.00000 atm 275 g V = ?? R = 8.31451 LkPa/molK 44.11g/mol 32.00 g/mol STP = 0.00 °C, 101.325 kPa 1 mol nC3H8 = 275g × = 6.23 mol 44.11g/mol SATP = 25.00 °C, 100.00 kPa 5 mol of O2 nO2 = 6.23 mol × = 31.2 mol 1 mol of C3H8 nRT 31.2 mol ×8.31451×273.15K VO2 = = = 699 L P 101.325 kP a Gravimetric and Gas Stoichiometry Overview 1. Write a balanced chemical equation and list the A typical Alberta home heated with natural gas (assume measurements, unknown quantity symbol, and methane, CH4(g)) consumes 2.00 ML of natural gas conversion factors for the measured and required during the month of December. What volume of oxygen substances. at SATP is required to burn 2.00 ML of methane 2. Convert the measured quantity to a chemical measured at 0 °C and 120 kPa? amount using the appropriate conversion factor. 3. Calculate the chemical amount of the required CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g) substance using the mole ratio from the balanced 2.00 ML V = ??? equation. = M = 4. Convert the calculated chemical amount to the 2.00 × 106L 32.00g/mol final quantity requested using the appropriate M = 16.05 conversion factor.
[Show full text]
Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: the Challenge of C6 and C5 Sugars Consumption
energies Article Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption Rita H. R. Branco, Mariana S. T. Amândio, Luísa S. Serafim and Ana M. R. B. Xavier * CICECO–Aveiro Institute of Materials, Chemistry Department, University of Aveiro, Campus Universitario de; Santiago, 3810-193 Aveiro, Portugal; [email protected] (R.H.R.B.); [email protected] (M.S.T.A.); luisa.serafi[email protected] (L.S.S.) * Correspondence: [email protected]; Tel.: +351-234-370-716 Received: 27 December 2019; Accepted: 4 February 2020; Published: 8 February 2020 Abstract: Second-generation bioethanol production’s main bottleneck is the need for a costly and technically difficult pretreatment due to the recalcitrance of lignocellulosic biomass (LCB). Chemical pulping can be considered as a LCB pretreatment since it removes lignin and targets hemicelluloses to some extent. Chemical pulps could be used to produce ethanol. The present study aimed to investigate the batch ethanol production from unbleached Kraft pulp of Eucalyptus globulus by separate hydrolysis and fermentation (SHF). Enzymatic hydrolysis of the pulp resulted in a glucose yield of 96.1 3.6% and a xylose yield of 94.0 7.1%. In an Erlenmeyer flask, fermentation of the ± ± hydrolysate using Saccharomyces cerevisiae showed better results than Scheffersomyces stipitis. At both the Erlenmeyer flask and bioreactor scale, co-cultures of S. cerevisiae and S. stipitis did not show significant improvements in the fermentation performance. The best result was provided by S. cerevisiae alone in a bioreactor, which fermented the Kraft pulp hydrolysate with an ethanol yield of 0.433 g g 1 and a volumetric ethanol productivity of 0.733 g L 1 h 1, and a maximum ethanol · − · − · − concentration of 19.24 g L 1 was attained.
[Show full text]
Stoichiometry: Predicting Amounts in Reactions
Name: Per: 4-4c: Stoichiometry: Predicting Amounts in Reactions Stoichiometry is the process of determining how much product is made or how much reactant is needed during a chemical reaction. As we know, in chemical reactions atoms are conserved. We show this in a balanced chemical equation. The balanced chemical equation tells us two things: 1. Which substances begin with (reactants) and end with (products) during the rearrangement process. 2. The ratio of particles involved. This ratio can be seen either as a ratio of individual particles OR as a ratio of moles. In the lab it is only practical to work with moles of substances rather than individual atoms or molecules, and so we interpret our equations as a ratio of moles, or a mole ratio. Example: 2 Mg + 1O2 → 2 MgO means for every 2 moles of Mg burned, 1 mole of O2 is required to produce 2 moles of MgO, or a ratio of 2 moles Mg : 1 mole O2 : 2 moles MgO We can use this mole ratio relationship to make predictions about how much we need of something, or how much we can make from what we have. Making Predictions In every reaction, there are three stages we need to consider to make good predictions: 1. Before: What we have before the reaction takes place. 2. Change: How much of each substance is formed (products) or rearranged (reactants) 3. After: How much of each substance is present after the reaction is complete. (difference between the Before and the Change) Some good organization can help us in making good predictions.
[Show full text]
Stoichiometry's PCK of University Chemistry Professors Abstract Keywords -...DR ANDONI GARRITZ RUIZ
Stoichiometry’s PCK of University Chemistry Professors Kira Padilla and Andoni Garritz Facultad de Química, Universidad Nacional Autónoma de México Ciudad Universitaria, Avenida Universidad 3000 04510 México, Distrito Federal, México Phone: (5255) 56223711 Fax: (5255) 56223439 Emails: [email protected]; [email protected] Abstract The purpose of this paper is to document the Pedagogical Content Knowledge (PCK) for a set of four university chemistry professors teaching Stoichiometry; i.e. the study of the mass and amount of substance ratios between two or more substances undergoing a chemical change or, in brief, ‘the science of chemical calculations’. This topic can be taught with a simple algorithmic purpose (going for immediate procedures without much understanding about what to do and/or why doing it) or it can be used to reinforce crucial concepts on the chemical reaction or even the particulate constitution of matter. A discussion is presented on the approach given by these four professors in their General Chemistry classes, which has been classified as Conceptual, Representational, Contextual and Procedural. Results are conclusive on the various pedagogical focuses on three of the approaches (Representational, Contextual and Procedural), and the equivalence of the four professors Conceptual approach. Results also reveal a link between Conceptual and Procedural knowledge. Keywords Pedagogical content knowledge, Content Representation, Conceptual profile zones, Stoichiometry, University level Introduction Shulman (1986, 1987) introduced the term pedagogical content knowledge (PCK) in order to draw attention to the value of the special amalgam of content and pedagogical knowledge that a teacher needs to be an outstanding one. Stoichiometry is a specific topic of the College General Chemistry course which PCK deserves to be documented and commented, as it has been pointed out by De Jong, Veal & Van Driel (2002).
[Show full text]
0.4314 Moles Pentane 2.157 Moles CO2 94.93 Grams of CO2 Produced
Stoichiometry Worksheet 1. In the combustion reaction of pentane with gaseous oxygen, CO2 and water vapor are produced. Ex: CH3CH2CH2CH2CH3 (l) + 8O2 (g) 5CO2 (g) + 6H2O (g) If you are given 31.125g of pentane to burn, how many grams of CO2 gas will be produced (assuming O2 (g) is in excess)? -the first step in a stoichiometry problem is to determine the number of moles of our reactants. We know that O2 is in excess, so we only need to convert pentane to moles. First we must find the molecular weight (MW) of pentane: MW of pentane: 72.15 grams/mole Now that we know the MW we can find the moles of pentane. Grams of pentane = 31.125g 0.4314 moles pentane MW of pentane = 72.15 g/mole Next, we will use the molar ratios to determine the moles of CO2 produced. CH3CH2CH2CH2CH3 (l) + 8O2 (g) 5CO2 (g) + 6H2O (g) Comparing the moles of pentane to that of CO2, it can be seen that the molar ratio is 1:5 pentane:carbon dioxide. -Multiply moles of pentane by the molar ratio to calculate the moles of CO2. 0.4314 moles pentane * 5 moles CO2 2.157 moles CO2 1 moles pentane -Lastly, the moles of CO2 must be converted to grams, this can be done through the use of the MW of CO2 = 44.01 g/mole. 2.157 moles of CO2 * MW of CO2 44.01 g/mole = 94.93 grams of CO2 produced 2. a) If you react 19.8 g of lead(II) nitrate with 12.4 g of sodium iodide, how much lead(II) iodide is formed? -Because we were given two amounts of our reactants, we know this is a limiting reactant problem and must first determine which reactant is limiting.
[Show full text]
Stoichiometry of Chemical Reactions 175
Chapter 4 Stoichiometry of Chemical Reactions 175 Chapter 4 Stoichiometry of Chemical Reactions Figure 4.1 Many modern rocket fuels are solid mixtures of substances combined in carefully measured amounts and ignited to yield a thrust-generating chemical reaction. (credit: modification of work by NASA) Chapter Outline 4.1 Writing and Balancing Chemical Equations 4.2 Classifying Chemical Reactions 4.3 Reaction Stoichiometry 4.4 Reaction Yields 4.5 Quantitative Chemical Analysis Introduction Solid-fuel rockets are a central feature in the world’s space exploration programs, including the new Space Launch System being developed by the National Aeronautics and Space Administration (NASA) to replace the retired Space Shuttle fleet (Figure 4.1). The engines of these rockets rely on carefully prepared solid mixtures of chemicals combined in precisely measured amounts. Igniting the mixture initiates a vigorous chemical reaction that rapidly generates large amounts of gaseous products. These gases are ejected from the rocket engine through its nozzle, providing the thrust needed to propel heavy payloads into space. Both the nature of this chemical reaction and the relationships between the amounts of the substances being consumed and produced by the reaction are critically important considerations that determine the success of the technology. This chapter will describe how to symbolize chemical reactions using chemical equations, how to classify some common chemical reactions by identifying patterns of reactivity, and how to determine the quantitative relations between the amounts of substances involved in chemical reactions—that is, the reaction stoichiometry. 176 Chapter 4 Stoichiometry of Chemical Reactions 4.1 Writing and Balancing Chemical Equations By the end of this section, you will be able to: • Derive chemical equations from narrative descriptions of chemical reactions.
[Show full text]
Article Metric to 'Green' Chemistry – Which Are the Best?
View Article Online / Journal Homepage / Table of Contents for this issue Metrics to ‘green’ chemistry—which are the best? David J. C. Constable,a Alan D. Curzonsb and Virginia L. Cunninghama a GlaxoSmithKline Pharmaceuticals, 2200 Renaissance Boulevard, King of Prussia, PA 19406, USA. E-mail: [email protected] b GlaxoSmithKline Pharmaceuticals, Southdownview Way, Worthing, West Sussex, UK BN14 8NQ Received 26th June 2002 First published as an Advance Article on the web 17th October 2002 A considerable amount has been written about the use of metrics to drive business, government and communities towards more sustainable practices. A number of metrics have also been proposed over the past 5U10 years to make chemists aware of the need to change the methods used for chemical syntheses and chemical processes. This paper explores several metrics commonly used by chemists and compares and contrasts these metrics with a new metric known as reaction mass efficiency. The paper also uses an economic analysis of four commercial pharmaceutical processes to understand the relationship between metrics and the most important cost drivers in these processes. Selected metrics used in the past autoclaved cell mass have some environmental impacts of one kind or another that would need to be evaluated and ad- A considerable number of publications have been written about dressed. the use of metrics to drive business, government and commu- nities towards more sustainable practices. The reader is referred elsewhere for a discussion of what metrics have
[Show full text]
Hydrogen Peroxide Formation and Stoichiometry of Hydroxylation Reactions Catalyzed by Highly Purified Liver Microsomal Cytochrome P-450’
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS 180, 343-347 (1977) Hydrogen Peroxide Formation and Stoichiometry of Hydroxylation Reactions Catalyzed by Highly Purified Liver Microsomal Cytochrome P-450’ GERALD D. NORDBLOM AND MINOR J. COON Department of Biological Chemistry, Medical School, The University of Michigan, Ann Arbor, Michigan 48109 Received July 23, 1976 The stoichiometry of hydroxylation reactions catalyzed by cytochrome P-450 was studied in a reconstituted enzyme system containing the highly purified cytochrome from phenobarbital-induced rabbit liver microsomes. Hydrogen peroxide was shown to be formed in the reconstituted system in the presence of NADPH and oxygen; the amount of peroxide produced varied with the substrated added. NADPH oxidation, oxygen consumption, and total product formation (sum of hydroxylated compound and hydrogen peroxide) were shown to be equimolar when cyclohexane, benzphetamine, or dimethylaniline served as the substrate. The stoichiometry observed represents the sum of two activities associated with cytochrome P-450. These are (1) hydroxylase activity: NADPH + H+ + O2 + RH + NADP+ + H,O + ROH; and (2) oxidase activity: NADPH + H+ + O2 + NADP+ + H,O,. Benzylamphetamine (desmethylbenzphetamine) acts as a pseudosubstrate in that it stimulates peroxide formation to the same extent as the parent compound (benzphetamine), but does not undergo hydroxylation. Accordingly, when benzylamphetamine alone is added in control experiments to correct for the NADPH and O2 consumption not associated with benzphetamine hydroxylation, the expected 1:l:l stoichiometry for NADPH oxidation, O2 consumption, and formaldehyde formation in the hydroxylation reaction is observed. Cytochrome P-450, the terminal oxidase purified enzyme fractions, the addition of of the liver microsomal mixed-function ox- catalase reduced the oxygen uptake to the idase system, catalyzes the NADPH-de- expected value (9).
[Show full text]
CHAPTER 9 Stoichiometry
CHAPTER 9 Stoichiometry Stoichiometry comes from the Greek words stoicheion, meaning “element,” and metron, meaning “measure.” Copyright © by Holt, Rinehart and Winston. All rights reserved. Introduction to SECTION 9-1 Stoichiometry OBJECTIVES Define stoichiometry. Describe the importance of the mole ratio in stoichio- M uch of our knowledge of chemistry is based on the careful quanti- metric calculations. tative analysis of substances involved in chemical reactions. Composition stoichiometry (which you studied in Chapter 3) deals with the mass rela- tionships of elements in compounds. Reaction stoichiometry involves the Write a mole ratio relating mass relationships between reactants and products in a chemical reaction. two substances in a chemical Reaction stoichiometry is the subject of this chapter and it is based on equation. chemical equations and the law of conservation of matter. All reaction- stoichiometry calculations start with a balanced chemical equation.This equation gives the relative numbers of moles of reactants and products. TERAC IN T I Reaction-Stoichiometry Problems V E CHEMISTRY • T The reaction-stoichiometry problems in this chapter can be classified U T O R according to the information given in the problem and the information Module 5: Equations and Stoichiometry you are expected to find, the unknown. The given and the unknown may both be reactants, they may both be products, or one may be a reactant and the other a product. The masses are generally expressed in grams, but you will encounter both large-scale and microscale problems with other mass units, such as kg or mg. Stoichiometric problems are solved by using ratios from the balanced equation to convert the given quanti- ty using the methods described here.
[Show full text]
Chemical Stoichiometry
Stoichiometry Chapter 3 Chemical Stoichiometry Stoichiometry - The study of quantities of materials consumed and produced in chemical reactions. 03_34 Detector plate Ion-accelerating electric field Least massive ions Accelerated ion beam Positive ions Sample Most massive ions Electron beam Slits Magnetic field Heating device to vaporize sample Schematic diagram of a mass spectrometer. Average Atomic Mass Elements occur in nature as mixtures of isotopes Carbon = 98.89% 12C 1.11% 13C <0.01% 14C (0.9889)(12.0000 amu) = 11.87 amu (0.0111)(13.0034 amu) = 0.144 amu 12.01 amu The Mole The number equal to the number of carbon atoms in exactly 12 grams of pure 12C. 1 mole of anything = 6.022 1023 units of that thing Equal moles of substances have equal numbers of atoms, molecules, ions, formula units, etc. Counting Atoms Atoms are too small to be seen or counted individually. Atoms can only be counted by weighing them. • all jelly beans are not identical. • jelly beans have an average mass of 5 g. • How could 1000 jelly beans be counted? Jelly Beans & Mints Mints have an average mass of 15 g. How would you count out 1000 mints? Why do 1000 mints have a mass greater than 1000 jelly beans? Atomic Mass Unit Atoms are so tiny that the gram is much too large to be practical. The mass of a single carbon atom is 1.99 x 10-23 g. The atomic mass unit (amu) is used for atoms and molecules. AMU’s and Grams 1 amu = 1.661 x 10 -24 g Conversion Factors 1.661 x 10-24g/amu 6.022 x 1023amu/g The Mole • One mole of rice grains is more than the number of grains of all rice grown since the beginning of time! • A mole of marshmallows would cover the U.S.
[Show full text]