Question 1

Which of the following statements best describes the internal energy ($U$) of a system?

Accepted Answer

It is the sum of the potential and kinetic energies of the component molecules.

Question 2

Which of the following is an endothermic process?

Accepted Answer

Melting solid ice

Question 3

Given the reaction: $\mathrm{H}_2(g) + \frac{1}{2}\mathrm{O}_2(g) \rightarrow \mathrm{H}_2O(l)$, if $\Delta H = -285.8\ \mathrm{kJ}$, what does the negative sign indicate?

Accepted Answer

The reaction is exothermic and releases heat.

Question 4

A compound with the formula $\mathrm{C}_2\mathrm{H}_6\mathrm{O}_2$ has a molar mass of $62.1\ \mathrm{g/mol}$. If the specific heat is $2.44\ \mathrm{J/g\cdot K}$, what is its molar heat capacity?

Accepted Answer

$151.5\ \mathrm{J/mol\cdot K}$

Question 5

The combustion of titanium with oxygen produces titanium dioxide: $\mathrm{Ti}(s) + \mathrm{O}_2(g) \rightarrow \mathrm{TiO}_2(s)$. If $0.80\ \mathrm{g}$ of titanium is combusted and the temperature of the calorimeter increases from $22.5^\circ\mathrm{C}$ to $25.3^\circ\mathrm{C}$, and the heat capacity of the calorimeter is $3.85\ \mathrm{J/K}$, what is the heat of reaction for the combustion of 1 mole of titanium?

Accepted Answer

$-314\ \mathrm{kJ}$

Question 6

Calculate the work ($w$) done during a reaction in which the external volume contracts from $8.1\ \mathrm{L}$ to $2.3\ \mathrm{L}$ against a constant pressure of $4.0\ \mathrm{atm}$.

Accepted Answer

$-23\ \mathrm{L\cdot atm}$

Question 7

Given the data in the table below, what is $\Delta H_{rxn}$ for the reaction $\mathrm{NH}_3(g) + \mathrm{O}_2(g) ightarrow \mathrm{NO}(g) + \mathrm{H}_2O(g)$?

\begin{align*}
\mathrm{NH}_3(g): &\quad -45.9\ \mathrm{kJ/mol} \
\mathrm{O}_2(g): &\quad 0\ \mathrm{kJ/mol} \
\mathrm{NO}(g): &\quad 90.3\ \mathrm{kJ/mol} \
\mathrm{H}_2O(g): &\quad -241.8\ \mathrm{kJ/mol}
\end{align*}

Accepted Answer

$-117.4\ \mathrm{kJ}$

Question 8

The value of $\Delta H$ for the reaction below is $-126\ \mathrm{kJ}$:

$\mathrm{CH}_4(g) + \mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g) + 2\mathrm{H}_2O(g)$

How many kJ of heat are released when $1.73\ \mathrm{g}$ of $\mathrm{CH}_4$ is burned as shown in the equation?

Accepted Answer

$-13.6\ \mathrm{kJ}$

Question 9

Which of the following molecules is polar?

Accepted Answer

$\mathrm{H}_2\mathrm{O}$

Question 10

According to VSEPR theory, the shape of $\mathrm{SF}_4$ is described as:

Accepted Answer

See-saw

Question 11

Which of the following molecules would have forced angles of approximately $180^\circ$?

Accepted Answer

$\mathrm{CO}_2$ only

Question 12

For a process at constant volume, which of the following is true?

Accepted Answer

$q = \Delta E$ and $\Delta H = \Delta E$

Question 13

In the drawing of acetic acid, $\mathrm{CH}_3\mathrm{CO}_2\mathrm{H}$, a partial positive charge ($\delta^+$) occurs on:

Accepted Answer

The hydrogen atom bonded to oxygen

Question 14

Which of the following molecules should have the lowest boiling point?

Accepted Answer

$\mathrm{CH}_4$

Question 15

Which of the following molecules is likely to be the most significant component of the total intermolecular forces formed by hydrogen bonding?

Accepted Answer

$\mathrm{H}_2\mathrm{O}$

Question 16

What is the molecular geometry of $\mathrm{SF}_6$?

Accepted Answer

Octahedral

Question 17

Which of the following molecules only have London dispersion forces as their primary intermolecular force?

Accepted Answer

$\mathrm{CH}_4$

Question 18

Which of the following is the best Lewis structure for $\mathrm{OCl}_2$?

Accepted Answer

A

Question 19

Which of the following are allowed resonance forms of $\mathrm{NCO}^-$?

Accepted Answer

I and II only

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