Q: A $$2.49\ \text{g}$$ sample of aniline ($$\text{C}_6\text{H}_5\text{NH}_2$$, molar mass $$= 93.13\ \text{g/mol}) is $$combusted in a bomb calorimeter with heat capacity $$4.25\ \text{kJ}/^\circ\text{C}. If $$the temperature rises from $$29.5^\circ\text{C} to$$ $$69.8^\circ\text{C}$$, what is $$\Delta H^\circ_{\text{comb}}$$ for aniline?

$$-1.71 \times 10^3$\ \text{kJ/mol}$$

Q: For the reaction $$2\ \text{H}_2\text{S}(g) + 3\ \text{O}_2(g) \rightarrow 2\ \text{SO}_2(g) + 2\ \text{H}_2\text{O}(g)$$ with $$\Delta H = -1036\ \text{kJ}$$ and $$\Delta S = -153.2\ \text{J/K}$$, above what temperature does the reaction become nonspontaneous?

$$6.762 \times 10^3$\ \text{K}$$

Q: Which balanced reaction corresponds to the following rate relationships? $$\text{Rate} = -\frac{1}{2} \frac{d[\text{N}_2\text{O}]}{dt} = \frac{d[\text{N}_2]}{dt} = \frac{1}{2} \frac{d[\text{O}_2]}{dt}$$

$$2\ \text{N}_2\text{O} \rightarrow 2\ \text{N}_2 + \text{O}_2$$

Q: Given the following data for the reaction $$\text{NO}_2(g) + \text{O}_3(g) \rightarrow \text{NO}_3(g) + \text{O}_2(g)$$: $$[\text{NO}_2]_i (M$$): $$0.10$$, $$0.10$$, $$0.25$$ $$[\text{O}_3]_i (M$$): $$0.33$$, $$0.66$$, $$0.66$$ Initial Rate (M/s): $$1.42$$, $$2.84$$, $$7.10$$ Determine the rate law and value of $$k.$$

Rate $$= [43\ \text{M}^{-1}\text{s}^{-1}][\text{NO}_2][\text{O}_3]$$

Q: A reaction has $$\Delta G^\circ = -50\ \text{kJ} at$$ $$298\ \text{K}. If $$the partial pressures of reactants are increased, what happens to $$\Delta G_{\text{rxn}}$$?

$$\Delta G_{\text{rxn}}$$ becomes less negative.

Question 1

Which statement about the law of conservation of energy is FALSE?

Accepted Answer

Energy cannot be transferred from one object to another.

Question 2

A system loses heat to the surroundings and the surroundings do work on the system. Which signs correctly represent $$q$$ and $$w$$ for the system?

Accepted Answer

$$q = -, w = +$$

Question 3

A system gives off $$25.0\ 	ext{kJ} of $$heat and its volume decreases from $$12.00\ 	ext{L} to$$ $$6.00\ 	ext{L} at$$ $$1.50\ 	ext{atm}. $$Calculate $$\Delta E in kJ$$. ($$101.3\ 	ext{J} = 1\ 	ext{L}\cdot	ext{atm})$$

Accepted Answer

$$-25.9\ 	ext{kJ}$$

Question 4

A $$2.49\ 	ext{g}$$ sample of aniline ($$	ext{C}_6	ext{H}_5	ext{NH}_2$$, molar mass $$= 93.13\ 	ext{g/mol}) is $$combusted in a bomb calorimeter with heat capacity $$4.25\ 	ext{kJ}/^\circ	ext{C}. If $$the temperature rises from $$29.5^\circ	ext{C} to$$ $$69.8^\circ	ext{C}$$, what is $$\Delta H^\circ_{	ext{comb}}$$ for aniline?

Accepted Answer

$$-1.71 	imes 10^3$\ 	ext{kJ/mol}$$

Question 5

A reaction has $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0. $$Which statement is TRUE?

Accepted Answer

This reaction will be nonspontaneous only at low temperatures.

Question 6

For the reaction $$2\ 	ext{H}_2	ext{S}(g) + 3\ 	ext{O}_2(g) ightarrow 2\ 	ext{SO}_2(g) + 2\ 	ext{H}_2	ext{O}(g)$$ with $$\Delta H = -1036\ 	ext{kJ}$$ and $$\Delta S = -153.2\ 	ext{J/K}$$, above what temperature does the reaction become nonspontaneous?

Accepted Answer

$$6.762 	imes 10^3$\ 	ext{K}$$

Question 7

Using Hess's law, calculate $$\Delta G^\circ_{	ext{rxn}}$$ for $$	ext{NO}(g) + 	ext{O}(g) ightarrow 	ext{NO}_2(g)$$ given:

$$2\ 	ext{O}_3(g) ightarrow 3\ 	ext{O}_2(g)$$, $$\Delta G^\circ_{	ext{rxn}} = +489.6\ 	ext{kJ}$$

$$	ext{O}_2(g) ightarrow 2\ 	ext{O}(g)$$, $$\Delta G^\circ_{	ext{rxn}} = +463.4\ 	ext{kJ}$$

$$	ext{NO}(g) + 	ext{O}_3(g) ightarrow 	ext{NO}_2(g) + 	ext{O}_2(g)$$, $$\Delta G^\circ_{	ext{rxn}} = -199.5\ 	ext{kJ}$$

Accepted Answer

$$-676.0\ 	ext{kJ}$$

Question 8

For the reaction $$2\ 	ext{Hg}(g) + 	ext{O}_2(g) ightarrow 2\ 	ext{HgO}(s)$$, $$\Delta G^\circ = -180.8\ 	ext{kJ}$$, and partial pressures $$P(	ext{Hg}) = 0.025\ 	ext{atm}$$, $$P(	ext{O}_2) = 0.037\ 	ext{atm} at$$ $$298\ 	ext{K}$$, calculate $$\Delta G_{	ext{rxn}}.$$

Accepted Answer

$$-26.5\ 	ext{kJ}$$

Question 9

Which balanced reaction corresponds to the following rate relationships?

$$	ext{Rate} = -\frac{1}{2} \frac{d[	ext{N}_2	ext{O}]}{dt} = \frac{d[	ext{N}_2]}{dt} = \frac{1}{2} \frac{d[	ext{O}_2]}{dt}$$

Accepted Answer

$$2\ 	ext{N}_2	ext{O} ightarrow 2\ 	ext{N}_2 + 	ext{O}_2$$

Question 10

Given the following data for the reaction $$	ext{NO}_2(g) + 	ext{O}_3(g) ightarrow 	ext{NO}_3(g) + 	ext{O}_2(g)$$:

$$[	ext{NO}_2]_i (M$$): $$0.10$$, $$0.10$$, $$0.25$$

$$[	ext{O}_3]_i (M$$): $$0.33$$, $$0.66$$, $$0.66$$

Initial Rate (M/s): $$1.42$$, $$2.84$$, $$7.10$$

Determine the rate law and value of $$k.$$

Accepted Answer

Rate $$= [43\ 	ext{M}^{-1}	ext{s}^{-1}][	ext{NO}_2][	ext{O}_3]$$

Question 11

A chemical reaction in a laboratory releases $$15.0\ 	ext{kJ} of $$heat and expands against a constant external pressure of $$2.00\ 	ext{atm}$$, increasing its volume by $$3.00\ 	ext{L}. $$What is the change in internal energy $$\Delta E$$? ($$1\ 	ext{L}\cdot	ext{atm} = 101.3\ 	ext{J})$$

Accepted Answer

$$-21.1\ 	ext{kJ}$$

Question 12

A reaction has $$\Delta H = -200\ 	ext{kJ}$$ and $$\Delta S = -400\ 	ext{J/K}. At $$what temperature does the reaction change from spontaneous to nonspontaneous?

Accepted Answer

$$500\ 	ext{K}$$

Question 13

Which scenario best illustrates the law of conservation of energy in a real-world context?

Accepted Answer

A battery converts chemical energy to electrical energy powering a flashlight.

Question 14

A reaction has $$\Delta H = +50\ 	ext{kJ}$$ and $$\Delta S = +200\ 	ext{J/K}. $$Will the reaction be spontaneous at $$T = 400\ 	ext{K}$$?

Accepted Answer

Yes, because $$\Delta G is $$negative.

Question 15

Which of the following best describes the effect of increasing temperature on a reaction with $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0$$?

Accepted Answer

The reaction becomes more spontaneous as temperature increases.

Question 16

A reaction has $$\Delta G^\circ = -50\ 	ext{kJ} at$$ $$298\ 	ext{K}. If $$the partial pressures of reactants are increased, what happens to $$\Delta G_{	ext{rxn}}$$?

Accepted Answer

$$\Delta G_{	ext{rxn}}$$ becomes less negative.

Question 17

Which of the following is a correct application of Hess's law?

Accepted Answer

Combining multiple reactions to calculate the overall $$\Delta G$$ for a desired reaction.

Question 18

In a bomb calorimeter experiment, why is the heat capacity of the calorimeter important?

Accepted Answer

It determines how much heat is absorbed for a given temperature change.

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