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 one of the following is an endothermic process?

Accepted Answer

Melting ice

Question 3

Calculate the value of $\Delta H$ for the reaction below, given the enthalpies of formation: $\mathrm{2H_2(g) + O_2(g) \rightarrow 2H_2O(l)}$; $\Delta H_f^\circ(\mathrm{H_2O(l)}) = -286\ \mathrm{kJ/mol}$.

Accepted Answer

$-572\ \mathrm{kJ}$

Question 4

A coffee-cup calorimeter contains 100.0 g of water at $22.0\ ^\circ\mathrm{C}$. When 4.18 g of NaCl is dissolved, the temperature drops to $20.5\ ^\circ\mathrm{C}$. What is the enthalpy change ($q$) for the dissolution process? ($c = 4.18\ \mathrm{J/g\cdot K}$)

Accepted Answer

$-627\ \mathrm{J}$

Question 5

Which of the following statements about bond enthalpy is correct?

Accepted Answer

Bond enthalpy is always positive because energy is required to break bonds.

Question 6

Given the reaction $\mathrm{CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(l)}$ and $\Delta H = -890.3\ \mathrm{kJ}$, how much heat is released when 16.0 g of methane is combusted?

Accepted Answer

$-890.3\ \mathrm{kJ}$

Question 7

Which of the following molecules has the largest London dispersion forces?

Accepted Answer

$\mathrm{C_6H_{14}}$

Question 8

What is the hybridization of the central carbon atom in $\mathrm{CO_2}$?

Accepted Answer

$sp$

Question 9

Which of the following molecules is polar?

Accepted Answer

$\mathrm{H_2O}$

Question 10

A sample of gas at $1.00\ \mathrm{atm}$ and $273\ \mathrm{K}$ occupies $22.4\ \mathrm{L}$. What is the molar mass of the gas if 44.8 g occupies this volume?

Accepted Answer

$44.8\ \mathrm{g/mol}$

Question 11

Which of the following best describes the shape of $\mathrm{SF_6}$ according to VSEPR theory?

Accepted Answer

Octahedral

Question 12

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

Accepted Answer

$\mathrm{CH_4}$

Question 13

Which of the following is the best Lewis structure for $\mathrm{OCl_2}$?

Accepted Answer

O with two single bonds to Cl, and two lone pairs on O

Question 14

Which of the following is true for a process at constant volume?

Accepted Answer

$q = \Delta U$ and $\Delta H = \Delta U + P\Delta V$

Question 15

Which of the following molecules is expected to have bond angles of approximately $109.5^\circ$?

Accepted Answer

$\mathrm{CH_4}$

Question 16

Which of the following is the correct order of decreasing F–C–F angle in the compounds below?
I. $\mathrm{BF_2}$
II. $\mathrm{CF_2}$
III. $\mathrm{CF_4}$

Accepted Answer

I > II > III

Question 17

Which of the following is paramagnetic?

Accepted Answer

$\mathrm{O_2}$

Question 18

Which of the following molecules is most likely to exhibit hydrogen bonding?

Accepted Answer

$\mathrm{NH_3}$

Question 19

Which of the following is the maximum number of covalent bonds that can be formed between two atoms?

Accepted Answer

3

Question 20

Which of the following is the correct electron configuration for $\mathrm{Fe^{2+}}$?

Accepted Answer

$[\mathrm{Ar}]\ 3d^6$

General Chemistry Practice Exam Study Guide: Thermochemistry, Bonding, Gases, and Molecular Structure

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