Question 1

Which of the following best describes the difference between thermodynamics and thermochemistry?

Accepted Answer

Thermodynamics is the study of the relationship between heat and other forms of energy, while thermochemistry focuses on the heat absorbed or evolved by a chemical reaction.

Question 2

A 75.0 kg person runs at a velocity of 1.78 m/s. What is their kinetic energy? Use $$E_K = \frac{1}{2}mv^2$.

Accepted Answer

$$E_K = 119\ \mathrm{J}$$

Question 3

Which of the following is an example of potential energy?

Accepted Answer

A compressed spring.

Question 4

The SI unit of energy is the joule (J). How many joules are in one calorie?

Accepted Answer

$$1\ \mathrm{cal} = 4.184\ \mathrm{J}$$

Question 5

Which of the following statements about the law of conservation of energy is correct?

Accepted Answer

Energy may be converted from one form to another, but the total quantity of energy remains constant.

Question 6

A system absorbs 300 J of heat from the surroundings and does 500 J of work on the surroundings. What is the change in internal energy ($$\Delta U) of $$the system? Use $$\Delta U = q + w.$$

Accepted Answer

$$\Delta U = -200\ \mathrm{J}$$

Question 7

Which of the following best describes an open system in thermodynamics?

Accepted Answer

A system where both mass and energy can enter or leave.

Question 8

In the context of thermodynamics, what is the correct sign convention for heat ($$q) $$and work ($$w$$)?

Accepted Answer

$$q is $$positive when heat is absorbed by the system; $$w is $$positive when work is done on the system.

Question 9

Which of the following is a state function?

Accepted Answer

Internal energy

Question 10

A chemical reaction in a beaker causes the beaker to feel cold to the touch. Which of the following statements is true?

Accepted Answer

The reaction is endothermic and $$q is $$positive.

Question 11

Which equation correctly relates enthalpy ($$H$$), internal energy ($$U$$), pressure ($$P$$), and volume ($$V$$)?

Accepted Answer

$$H = U + PV$$

Question 12

For the reaction $$2\mathrm{Na}(s) + 2\mathrm{H}_2\mathrm{O}(l) \rightarrow 2\mathrm{NaOH}(aq) + \mathrm{H}_2(g)$$, $$\Delta H = -368.6\ \mathrm{kJ}. $$What does the negative sign of $$\Delta H$$ indicate?

Accepted Answer

The reaction is exothermic and releases heat.

Question 13

Which of the following is true about pressure-volume work ($$w) in $$the context of a chemical reaction at constant pressure?

Accepted Answer

If the system expands ($$\Delta V \u003e 0$$), work is done by the system and $$w is $$negative.

Question 14

Calculate the pressure-volume work done when 1 mole of gas is compressed at 298 K and 1.00 bar. Use $$w = -\Delta n$$_{gas}$$RT$$ and $$R = 8.314\ \mathrm{J\ $$mol^{-1}$$\ K$$^{-1}$$}.$$

Accepted Answer

$$w = +2480\ \mathrm{J}$$

Question 15

Which of the following is NOT an extensive property?

Accepted Answer

Temperature

Question 16

Which of the following best describes a thermochemical equation?

Accepted Answer

A chemical equation that includes the enthalpy change for the reaction as written.

Question 17

If a thermochemical equation is multiplied by a factor of 2, what happens to the value of $$\Delta H$$?

Accepted Answer

$$\Delta H is $$multiplied by 2.

Question 18

Which of the following processes is exothermic?

Accepted Answer

Water vapor condensing on a cold pipe.

Question 19

Which of the following is true about the relationship between $$\Delta H$$ and $$q at $$constant pressure?

Accepted Answer

$$\Delta H = q_p ($$heat at constant pressure)

General Chemistry II: Thermochemistry and the First Law of Thermodynamics

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