Question 1

A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.800 atm. What is the value of work ($$w) $$done by the system, in Joules? ($$1 \ \mathrm{L \cdot atm} = 101.3 \ \mathrm{J})$$

Accepted Answer

$$w = -405 \ \mathrm{J}$$

Question 2

Which of the following statements is/are true regarding thermochemical processes?
I: The combustion of gasoline is an exothermic process in which $$\Delta H \u003e 0
II$$: The evaporation of sweat is an endothermic process in which $$\Delta H \u003e 0$$
III: The enthalpy of formation of oxygen gas is a process in which $$\Delta H = 0$$

Accepted Answer

II and III

Question 3

For the reaction $$\frac{1}{2} \mathrm{N}_2(g) + \frac{3}{2} \mathrm{H}_2(g) \rightarrow \mathrm{NH}_3(g) at 200$$°C and constant pressure, calculate the work done (in Joules) using $$R = 8.314 \ \mathrm{J/(mol \cdot K)}$$ and $$T = 473 \ \mathrm{K}.$$

Accepted Answer

$$w = -1,180 \ \mathrm{J}$$

Question 4

A 275-g sample of nickel at 100.0°C is placed in 100.0 mL of water at 22.0°C. What is the final temperature of the water? (Specific heat of Ni = $$0.444 \ \mathrm{J/g \cdot K}$$, water = $$4.184 \ \mathrm{J/g \cdot K})$$

Accepted Answer

$$T_f = 27.1^\circ \mathrm{C}$$

Question 5

Given the reaction $$\mathrm{C}_6\mathrm{H}_{12}(l) + 9 \mathrm{O}_2(g) \rightarrow 6 \mathrm{CO}_2(g) + 6 \mathrm{H}_2\mathrm{O}(l)$$ with $$\Delta H^\circ_{\mathrm{rxn}} = -3919.6 \ \mathrm{kJ}$$, $$\Delta H^\circ_f(\mathrm{CO}_2) = -393.5 \ \mathrm{kJ/mol}$$, and $$\Delta H^\circ_f(\mathrm{H}_2\mathrm{O}) = -285.8 \ \mathrm{kJ/mol}$$, what is $$\Delta H^\circ_f$$ for cyclohexane ($$\mathrm{C}_6\mathrm{H}_{12}$$)?

Accepted Answer

$$-156.2 \ \mathrm{kJ/mol}$$

Question 6

Which of the following will have $$\Delta H$$ greater than $$\Delta U$$?
I. $$2 \mathrm{H}_2(g) + \mathrm{O}_2(g) \rightarrow 2 \mathrm{H}_2\mathrm{O}(g)
II$$. $$\mathrm{MgSO}_3(s) + 2 \mathrm{HI}(aq) \rightarrow \mathrm{MgI}_2(aq) + \mathrm{H}_2\mathrm{O}(l) + \mathrm{SO}_2(g)$$
III. $$\mathrm{CO}(g) + \mathrm{H}_2\mathrm{O}(g) \rightarrow \mathrm{CO}_2(g) + \mathrm{H}_2(g)
IV$$. $$\mathrm{H}_2\mathrm{SO}_4(aq) + \mathrm{Li}_2\mathrm{S}(aq) \rightarrow \mathrm{H}_2\mathrm{S}(g) + \mathrm{Li}_2\mathrm{SO}_4(aq)$$

Accepted Answer

I, II, and III

Question 7

Which 1:1 ion combination among A, B, C, X, Y, Z (see image) has the lowest lattice energy?

Accepted Answer

CZ

Question 8

Using the Born-Haber cycle data provided, what is the standard enthalpy of formation ($$\Delta H^\circ_f) $$for $$\mathrm{CuCl}_2(s)$$, and which compound is more stable: $$\mathrm{CuCl}_2(s) or$$ $$\mathrm{CuCl}(s)$$?

Accepted Answer

$$\Delta H^\circ_f of$$ $$\mathrm{CuCl}_2(s) = -195.7 \ \mathrm{kJ/mol}$$; $$\mathrm{CuCl}_2(s) is $$more stable.

Question 9

Which of the following XO$$_3$$ ions has an expanded octet (more than eight electrons) on the central atom?

Accepted Answer

$$\mathrm{ClO}_3^-$$

Question 10

Match each element with the correct sphere based on atomic radius: Al atom, C atom, Cs atom.

Accepted Answer

Al atom: (III); C atom: (II); Cs atom: (I)

Question 11

Which equation correctly represents the first three ionization energies for bromine (Br), and which process requires the least energy?

Accepted Answer

IE1: Br → Br$$^+ + e$^-$$; IE2: Br$$^+$$ → Br$$^{2+} + e$^-$$; IE3: Br$$^{2+}$$ → Br$$^{3+} + e$^-$$; The first ionization energy has the least energy because it is farthest from the nucleus of the atom.

Question 12

Which of the following subshells can contain 4 electrons all with spin quantum number $$m_s = -1/2$$?

Accepted Answer

3d, 4d, and 5d

Question 13

Which of the following compounds will have a net (nonzero) dipole moment?
(i) AsCl$$_5
(ii) $$Fluoromethane, CH$$_3F
($$iii) SeCl$$_6
(iv) SF$_2$$

Accepted Answer

(ii) Fluoromethane, CH$$_3F $$has a net dipole moment. F is more electronegative than C and H and because it has a tetrahedral geometry, the dipole moments are not canceled out.
(iv) SF$$_2$$ has a net dipole moment. F is more electronegative than C and H and because it has a tetrahedral geometry, the dipole moments are not canceled out.

Question 14

Which of the following best describes the first law of thermodynamics?

Accepted Answer

The total energy of the universe is constant; energy can be transferred or transformed but not created or destroyed.

Question 15

Which equation correctly expresses the relationship between internal energy, heat, and work?

Accepted Answer

$$\Delta U = q + w$$

Question 16

Which of the following processes is both endothermic and involves work done by the system on the surroundings?

Accepted Answer

Benzene (l) $$\rightarrow$$ Benzene (g)

Thermochemistry, Quantum Mechanics, and Chemical Bonding: General Chemistry Study Guide

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