Exam 2 Ochem

What is the IUPAC name for the following compound?

1-Cyclopentylhexane

What is the IUPAC name for the following compound?

1-sec-Butyl-4-isopropyl-2-methylcyclohexane

What is the IUPAC name for the following alkane?

2,3,4,7-tetramethyloctane

What is the IUPAC name for the following compound?

3,5-Diethyl-2-methylheptane

What is the IUPAC name for the following compound?

3-Ethyl-2,5-dimethylheptane

What is the IUPAC name of the following compound?

3-Ethyl-2-methylpentane

What is the IUPAC name for the following alkane?

3-ethyl-2,6-dimethyloctane

How many constitutional isomers are there with the molecular formula C6H14?

5 C

A natural product was isolated in the laboratory, and its observed rotation was +10° when measured in a 1 dm sample tube containing 1.0 g of compound in 10 mL of H2O. What is the specific rotation of this compound? C, -10° B, -100° A, +100° D, +10°

A, +100°

How much of the R enantiomer is present in 10 g of a mixture that has an enantiomeric excess of 30% of the S isomer? B, 3.0 g C, 7.0 g D, 6.5 g A, 3.5 g

A, 3.5 g

What is the relationship between the following two compounds? A, Constitutional isomers B, Stereoisomers C, Identical D, Not isomers, different compounds

A, Constitutional isomers

What is the relationship between the following two compounds? A, Identical B. Constitutional isomers C, Stereoisomers D, Not isomers, different compounds

A, Identical

What is the relationship between the following two compounds? D, Not isomers, different compounds C, Identical B, Constitutional isomers A, Stereoisomers

A, Stereoisomers

Which of the following statements about stereoisomers is not true? A, Stereoisomers differ only in their structural formula. C, Stereoisomers have identical IUPAC names except for a prefix like cis or trans. B, Stereoisomers always have the same functional groups. D, Stereoisomers differ in configuration.

A, Stereoisomers differ only in their structural formula.

Calculate Ea for the conversion of C ® B. B. +7 kcal D. None of these C. +3 kcal A. +9 kcal

A. +9 kcal

What kind of reaction does the conversion of A to B represent? B. Substitution reaction D. Elimination reaction A. Addition reaction C. Acid-base reaction

A. Addition reaction

Which of the following statements is true? A. Bond dissociation energies decrease down a column of the periodic table. C. When DH° is positive, more energy is released in forming bonds than is needed to break bonds. B. When DH° is negative, more energy is needed to break bonds than is released in forming bonds. D. Bond dissociation energies increase down a column of the periodic table.

A. Bond dissociation energies decrease down a column of the periodic table.

Which of the following statements is true? A. Carbocations are electrophiles. B. Radicals are nucleophiles. D. Radicals are intermediates in polar reactions. C. Ionic intermediates are formed in radical reactions.

A. Carbocations are electrophiles.

Which of the following statements about bond breaking is true? C. Homolysis generates charged intermediates. D. In homolysis, the electrons in the bond are divided unequally. B. In heterolysis, the electrons in the bond are divided equally. A. Homolysis and heterolysis require energy.

A. Homolysis and heterolysis require energy.

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: What is the rate equation for this reaction if the first step is rate determining? A. Rate = k [acetyl chloride] [-OCH3] D. Rate = k [acetyl chloride] C. Rate = k [-OCH3] B. Rate = k [acetyl chloride] [-OCH3]2

A. Rate = k [acetyl chloride] [-OCH3]

What kind of reaction does the conversion of A to B represent? D. Addition reaction C. Acid-base reaction B. Elimination reaction A. Substitution reaction

A. Substitution reaction

Which of the following statements about the equilibrium constant, Keq, is true? B. When Keq > 1, the equilibrium favors the reactants. C. When Keq < 1, the equilibrium favors the products. A. The size of Keq tells about the position of equilibrium. D. For a reaction to be useful, the equilibrium must favor the reactants.

A. The size of Keq tells about the position of equilibrium

Which of the following statements about alkanes is not true?

Acyclic alkanes have two fewer H C atoms than cyclic alkanes with the same number of carbons.

Which reaction is fast and has Keq = 1? B D, A C

B

How many chiral stereoisomers can be drawn for dimethycyclopropane? C, 3 D, 4 A, 1 B, 2

B, 2

What is the total number of possible stereoisomers for the following molecule? C, 2 A, 4 B, 8 D, 6

B, 8

Which of the following statements is true? D, A chiral molecule usually contains a plane of symmetry. B, Enantiomers are mirror images that are not superimposable. C, A molecule that is superimposable on its mirror image is chiral. A, An achiral molecule does not contain a plane of symmetry.

B, Enantiomers are mirror images that are not superimposable.

Using the bond dissociation energies given, calculate DH° for the following reaction. C. +70 KJ/mol B. -3 KJ/mol A. -67 KJ/mol D. +3 KJ/mol

B. -3 KJ/mol

Which step would most likely have the largest energy of activation? B. Step one A. Step two C. Step three D. It cannot be determined from the information provided

B. Step one

Which of the following statements is not true? B. The bond dissociation energy for bond breaking is always negative. C. Bond breaking is endothermic. A. The bond dissociation energy for bond formation is always negative. D. Bond making is exothermic.

B. The bond dissociation energy for bond breaking is always negative.

How many stereogenic centers are present in ephedrine, a bronchodilator and decongestant? B, 1 C, 2 D, 3 A, 0

C, 2

How many stereogenic centers are present in menthol? C, 3 A, 1 B, 2 D, 4

C, 3

What is the percent ee of a mixture that has 70% of one enantiomer and 30% of the other? D, 85 B, 30 A, 70 C, 40

C, 40

Which of the following is the definition for a pair of diastereomers? C, A pair of stereoisomers that are not mirror images of each other. D, A pair of stereoisomers that are not superimposable mirror images of each other. A, A pair of stereoisomers with stereogenic centers but is not chiral. B, A pair of stereoisomers that are superimposable mirror images of each other.

C, A pair of stereoisomers that are not mirror images of each other.

Which of the following molecules are achiral? D, I, II B, II, III C, I, IV A, III, IV

C, I, IV

Rank the following groups in order of decreasing priority according to the Cahn-Ingold-Prelog system. C, II > I > IV > III A, II > I > III > IV B, I > II > III > IV D, I > II > IV > III

C, II > I > IV > III

Which of the following molecules are chiral? I. cis-1,3-Dibromocyclohexane II. 1-Bromo-1-methylcyclohexane III. trans-1-Bromo-3-methylcyclohexane IV. cis-1-Bromo-3-methylcyclohexane

C, III, IV

How many transition states are present in the reaction in the energy diagram? B. 1 A. 0 D. 3 C. 2

C. 2

Which of the following statements is true? C. Entropy decreases when an acyclic compound forms a ring. B. The product is favored in reaction in which DH° is a positive value. D. The starting material is favored in a reaction in which DH° is a negative value. A. In homolytic bond cleavage, entropy decreases and favors formation of products.

C. Entropy decreases when an acyclic compound forms a ring.

What is the molecular formula of an alkane that has twenty-three carbon atoms?

C23H48

Which formula represents a cycloalkane with 5 carbons?

C5H10

What is the molecular formula of a cycloalkane that has six carbon atoms?

C6H12

What are the products of the combustion of alkanes?

Carbon dioxide and water

Which of the following statements about alkanes is true?

Cyclic alkanes have two fewer H atoms than acyclic alkanes with the same number of carbons.

Which of the following letters represents DH° for the forward reaction in the following energy diagram? C A D B

D

Which of the following compounds is a meso compound? A, (2R, 3R)-dichlorobutane B, (2R, 3R)-3-chloro-2-butanol C, (2R, 3S)-3-chloro-2-butanol D, (2R, 3S)-dichlorobutane

D, (2R, 3S)-dichlorobutane

How many stereogenic centers are present in the following compound? C, 2 A, 0 D, 3 B, 1

D, 3

How many stereoisomers are possible for a molecule with formula CH3CHBrCH(OH)CH3? A, 1 B, 2 C, 3 D, 4

D, 4

Which of the following statements is true? B. A rate equation contains concentration terms for all the reactants involved in a multi-step reaction. C. Fast reactions have small rate constants. D. A rate equation contains concentration terms for all reactants involved in a one-step mechanism. A. Slow reactions have large rate constants.

D. A rate equation contains concentration terms for all reactants involved in a one-step mechanism.

What kind of reaction does the conversion of A to B represent? C. Addition reaction D. Elimination reaction B. Oxidation-reduction reaction A. Substitution reaction

D. Elimination reaction

If the conversion of A to B is slow and B to C is fast, what is the rate equation for this reaction? A. Rate = k[(CH3)2CH]+ B. Rate = k[(CH3)2CHCl][H2O] D. Rate = k[(CH3)2CHCl] C. Rate = k[(CH3)2CH]+[H2O]

D. Rate = k[(CH3)2CHCl]

Which of the following statements is not true? D. deltaH° determines the height of the energy barrier. B. The larger the activation energy, the slower the reaction. A. Two reactions can have identical values for H° but very different Ea values. C. The lower the activation energy, the faster the reaction.

D. deltaH° determines the height of the energy barrier.

Which of the following are anti conformers?

II and IV

Rank the conformers of 1,2,4-trimethylcyclohexane in order of decreasing stability, putting the most stable first.

III > IV > II > I C

Rank the conformers of butane in order of decreasing stability, putting the most stable first.

IV > I > III > II

Rank the following alkanes in order of increasing boiling point.

IV > III > II > I

What is the relation between the following pair of compounds?

Stereoisomers

Which of the following statements about substitution reactions is true? C. One σ bond breaks and another forms at a different carbon atom. A. Substitution reactions involve π bonds. B. One π bond breaks and another forms at the same carbon atom. D. Substitution reactions involve σ bonds.

Substitution reactions involve σ bonds

Which of the following statements about constitutional isomers is not true? D, They always have the same functional groups. C,They have different IUPAC names. A, They have different physical properties. B, They have different chemical properties.

They always have the same functional groups.

What is the hybridization of a carbon atom in an alkane?

sp3 A