Deck 2: Alkanes and Cycloakanes: Introduction to Hydrocarbons

Question 1

Alkanes are characterized by the general molecular formula:

A) $\mathrm{C}_{n} \mathrm{H}_{2 \mathrm{n}-2}$
B) $\mathrm{C}_{n} \mathrm{H}_{2 n}$
C) $\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}+2}$
D) $\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}+4}$

Answer 1

$\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}+2}$

Question 2

Cycloalkanes are characterized by the general molecular formula:

A) $\mathrm{C}_{n} \mathrm{H}_{2 n-2}$
B) $\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}}$
C) $\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}+2}$
D) $\mathrm{C}_{n} \mathrm{H}_{2 n+4}$

Answer 2

$\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}}$

Question 3

The carbon-carbon sigma bond in ethane is formed by overlap of which two orbitals?

A) $2 p-2 p$
B) $\mathrm{sp}-\mathrm{sp}$
C) $\mathrm{sp}^{2}-\mathrm{sp}^{2}$
D) $\mathrm{sp}^{3}-\mathrm{sp}^{3}$

Answer 3

$\mathrm{sp}^{3}-\mathrm{sp}^{3}$

Question 4

What is the IUPAC name of the following?

A) 1-ethyl-4.4-dimethylcyclopentane
B) 1-ethyl-3, 3-dimethylcyclopentane
C) 3-ethyl-1, 1-dimethylcyclopentane
D) 4-ethyl-1, 1-dimethylcyclopentane

Question 5

The $\mathrm{C}-\mathrm{C}$ sigma bond in acetylene is formed by the overlap of which two orbitals?
$\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}$

A) $2 \mathrm{p}-2 \mathrm{p}$
B) $\mathrm{sp}-\mathrm{sp}$
C) $\mathrm{sp}^{2}-\mathrm{sp}^{2}$
D) $\mathrm{sp}^{3}-\mathrm{sp}^{3}$

Question 6

Which of the following are constitutional isomers?

A) I, II, and III
B) I, III, and IV
C) only I and III
D) all are constitutional isomers.

Question 7

Arrange the following isomeric alkanes in order of increasing boiling point.
I. $n$ -heptane
II. 2,3-dimethylpentane
III. 2,2,3-trimethylbutane

A) I $<$ II $<$ III
B) II $<$ III $<$ I
C) III $<$ I $<$ II
D) III $<$ II $<$ I

Question 8

Which of the following has(have) a higher oxidation state of carbon than the carbon in formaldehyde, $\mathrm{H}_{2} \mathrm{C}=\mathrm{O}$ ?
I. $\mathrm{CH}_{3} \mathrm{OH}$
II. $\mathrm{HCO}_{2} \mathrm{H}$
III. $\mathrm{H}_{2} \mathrm{CO}_{3}$

A) I
B) III
C) II and III
D) I, II, and III

Question 9

Carbon atoms 1,2 , and 3 in the following structure are classified, respectively, as

A) tertiary, primary, secondary.
B) quaternary, primary, tertiary.
C) quaternary, secondary, secondary.
D) quaternary, secondary, tertiary.

Question 10

The heats of combustion $\left(-\Delta H^{\circ}\right)$ of heptane and 3,3-dimethypentane are 4,817 and $4,809 \mathrm{~kJ} / \mathrm{mol}$ , respectively. Which statement is true?

A) Heptane is $8 \mathrm{~kJ} / \mathrm{mol}$ more stable then 3,3-dimethylpentane.
B) 3,3-Dimethylpentane is $8 \mathrm{~kJ} / \mathrm{mol}$ more stable than heptane.
C) Stabilities cannot be compared since they are not isomers.
D) Stabilities cannot be compared since they give different combustion products.

Question 11

The reaction of acetylene with hydrogen gas is shown below. Which statements are true concerning the reaction?
$$\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+2 \mathrm{H}_{2} \xrightarrow{\mathrm{Pd} \text { (cat.) }} \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}$$
I. Acetylene is oxidized to ethane.
II. Acetylene is reduced to ethane.
III. Carbon changes oxidation state from -1 to -3 .
IV. Hydrogen (from $\mathrm{H}_{2}$ ) changes oxidation state from 0 to +1 .

A) I and III
B) II and IV
C) I, III, and IV
D) II, III, and IV

Question 12

How many moles of $\mathrm{O}_{2}$ gas would be consumed in the complete combustion of 0.100 mole of $\mathrm{C}_{5} \mathrm{H}_{12}$ ?

A) 0.100 mole $\mathrm{O}_{2}$
B) 0.400 mole $\mathrm{O}_{2}$
C) 0.800 mole $\mathrm{O}_{2}$
D) $1.60 \mathrm{~mole}_{2}$

Question 13

What is the relationship between the two structures below?

A) identical structures
B) resonance forms
C) constitutional isomers
D) different compounds with different compositions

Question 14

What is the IUPAC name of the following structure?

A) 3-propylpentane
B) 3-ethylhexane
C) 2-ethylheptane
D) 4-ethylpentane

Question 15

What is the estimated $\mathrm{C}-\mathrm{C}-\mathrm{C}$ bond angle in the following structure?

A) $90^{\circ}$
B) $109.5^{\circ}$
C) $120^{\circ}$
D) $180^{\circ}$

Question 16

The $\mathrm{sp}^{3}$ orbitals of carbon in $\mathrm{CH}_{4}$ are formed from the

A) three $2 p$ orbitals.
B) $2 \mathrm{~s}$ and one of the $2 \mathrm{p}$ orbitals.
C) $2 \mathrm{~s}$ and two of the $2 \mathrm{p}$ orbitals.
D) $2 \mathrm{~s}$ and the three $2 \mathrm{p}$ orbitals.

Question 17

What is the $\mathrm{Cl}-\mathrm{C}-\mathrm{Cl}$ bond angle in $\mathrm{CCl}_{4}$ ?

A) $60^{\circ}$
B) $90^{\circ}$
C) $109.5^{\circ}$
D) $120^{\circ}$

Question 18

The carbon-carbon single bond in the following is formed by the overlap of which two orbitals?
$\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{C} \equiv \mathrm{N}$

A) $\mathrm{sp}-\mathrm{sp}$
B) $\mathrm{sp}^{2}-\mathrm{sp}$
C) $\mathrm{sp}^{2}-\mathrm{sp}^{2}$
D) $\mathrm{sp}^{2}-\mathrm{sp}^{3}$