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

General Chemistry Practice Exam Study Guide

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