sign in sign up
<<
Home , Sigma bond

CHEM311 Your Name:______FALL 2005 Practice Exam #1 Signature:______

Instructions: This is a multiple choice / short answer PRACTICE exam. For the multiple-choice questions, there may be more than one correct answer. If so, then circle as many answers as you believe to be correct. You will get 3 pts for each correct response and –1 for each wrong response. If there is a choice of “other”, and you choose “other”, you MUST provide a correct alternative answer on the line provided in order to get the question right. Only choose “other” if there are no correct answers present. The short answer questions are worth 5 to 15 points each. Where I have asked for you to draw a structure or mechanism, be very precise with your arrows and such…don’t make me guess as to what you meant. You may only use a pen or pencil, big eraser, and a molecular model set to take this exam. You have 60 minutes to complete this exam. Your signature above indicates that you have taken this exam in accordance with the University Honor Code. Good luck!

OH

Compound A

1) A proper IUPAC name for Compound A is… a. 3-isopropanol-4-ethyl-4-heptyne b. 3,4-diethyl-3-hexen-2-ol c. 2-hydroxy-3-ene-bipentane d. semicycloheptenol e. other ______

2) Excluding alkyl groups, the main functional groups in Compound A are... a. alcohol, b. , halide c. alcohol, ethyl d. aldehyde, halide e. other ______

3) Which below adequately describes the hybrdization states of the carbon atoms in Compound A? a. all are sp3 b. 4 are sp3, 4 are sp2, 2 are sp c. 4 are primary, 4 are secondary and 2 are sp2 d. 2 are sp2 and 8 are sp3 e. other ______

1

4) What is the molecular formula of compound A? a. C10H22O b. C6H8OH c. C8H2OH d. C10H19O e. other ______

5) A sigma bond… a. …is one in which the density lies in between the nuclei b. …allows for free rotation round the bond c. …results from the indirect overlap of p-orbitals d. …results from ionic interaction of s-orbitals e. other ______

6) A … a. …has a nodal plane that cuts through the two nuclei b. … is one in which the lies in between the nuclei c. …may allow for structures of charged to be drawn d. …results from small electronegativity differences between different carbons e. other ______

7) A carbon-carbon consists of… a. …2 sp2 hybridized carbon atoms b. …a sigma bond and a pi bond c. …a sigma bond and 2 pi bonds d. …an ionic bond and a sigma bond e. other ______

8) A carbon-carbon … a. …consists of two carbons with sp hybridization b. …is longer than a C-C c. …has linear geometry d. …consists of two sigma bonds and one pi bond e. other ______

9) Which of the following are true? a. heptene has a molecular formula of C7H14 b. eicosane has 20 carbons c. cyclooctadienol has two OH’s d. 2-butyne is a linear e. none are true.

10) Hexane is a common organic solvent. Which compound is likely most readily soluble in hexane and why? a. decane because it is a non-polar straight chain compound like hexane. b. cyclohexanol, because it is has six carbons like hexane. c. water, because it is a common solvent just like hexane. d. acetic acid, because that is how we make Italian dressing e. other ______

2 11) Octanol is a common solvent, particularly in environmental research because it mimics the chemical properties of living tissue. Which compound is likely most readily soluble in octanol and why? a. cyclohexanol, because it can bond like octanol. b. octadecane, because it has 18 carbons just like octanol c. water, because it is a common solvent found in environmental systems d. polyaromatic hydrocarbons, because both have lots of double bonds. e. other ______

Compound B = 3,4-diethyl-2,5-dimethyl-2,4-cyclopentadienol

12) Draw (with great precision) compound B.

13) The common name for compound B is... a. trimyristin b. alkylpentaneneol c. humenol (because it looks like a little person) d. Our professor is nuts…there is no common name, he/she just makes this @#$% up. e. Other ______

14) The molecular formula of Compound B is… a. C11H18O b. C11H17O c. C9H20O2 d. C11H22O e. other ______

15) Compound B has… a. two double bonds b. has 4 primary carbons c. has 2 secondary carbons d. has a molecular charge of –1 e. other ______

3 16) I have just removed a hydride (H-) from the #1 carbon on compound B to make a cation at carbon number 1. Draw the cation and any two other resonance forms using the proper arrow notation (be precise).

17) When drawing resonance structures… a. …you are allowed to move if necessary b. …you can only move c. …you can move double bonds anywhere you deem necessary d. …you can only move electrons if they are in the longest continuous chain e. other ______

18) When naming organic compounds… a. …first number the compound b. …first find the longest carbon chain (or biggest ring) that contains the highest priority functional group c. …first locate all the halogens d. …first look up the common name on the internet e. other ______

19) Carbon single, double and triple bonds have different bond lengths and strengths. Demonstrate to me that you understand why by completing the table below by assigning the hybridization states of the 2 carbons involved (e.g., sp2-sp3), giving me the % s and p character in the bond, and telling which is longest, shortest, strongest, etc.

Bond type hybridization % s character % p character length strength single double triple

4