Question 1

Which of the following best describes an exothermic reaction and how it would feel to the surroundings?

Accepted Answer

An exothermic reaction releases heat, so the surroundings feel warmer.

Question 2

A sample of water absorbs $$500\ \mathrm{cal} of $$heat. How much energy is this in joules? (Given: $$1\ \mathrm{cal} = 4.184\ \mathrm{J})$$

Accepted Answer

$$2092\ \mathrm{J}$$

Question 3

Which of the following best defines a closed system in thermodynamics?

Accepted Answer

A system that can exchange energy but not matter with its surroundings.

Question 4

Which statement correctly expresses the first law of thermodynamics?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 5

For an endothermic reaction, what are the signs of $$q$$ and $$\Delta H$$?

Accepted Answer

$$q \u003e 0$$ and $$\Delta H \u003e 0$$

Question 6

Which equation is used to calculate the heat absorbed or released by a substance, and what does each variable represent?

Accepted Answer

$$q = ms\Delta T$$, where $$q is $$heat, $$m is $$mass, $$s is $$specific heat, and $$\Delta T is $$the temperature change.

Question 7

A $$50.0\ \mathrm{g}$$ sample of metal at $$100.0\ ^\circ\mathrm{C} is $$placed in $$100.0\ \mathrm{g} of $$water at $$25.0\ ^\circ\mathrm{C}. $$The final temperature is $$30.0\ ^\circ\mathrm{C}. If $$the specific heat of water is $$4.18\ \mathrm{J/g\ ^\circ C}$$, how much heat did the water absorb?

Accepted Answer

$$2090\ \mathrm{J}$$

Question 8

Which of the following is the correct application of Hess's Law?

Accepted Answer

The enthalpy change for an overall reaction is the sum of the enthalpy changes for the individual steps.

Question 9

Which of the following is NOT a property of gases?

Accepted Answer

Gases have a definite shape and volume.

Question 10

A sample of gas occupies $$2.0\ \mathrm{L} at$$ $$1.0\ \mathrm{atm}$$ and $$300\ \mathrm{K}. $$What will be its volume at $$2.0\ \mathrm{atm}$$ and $$300\ \mathrm{K}$$, assuming the amount of gas remains constant?

Accepted Answer

$$1.0\ \mathrm{L}$$

Question 11

Which equation represents the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 12

At STP ($$1.00\ \mathrm{atm}$$ and $$273\ \mathrm{K}$$), what is the volume occupied by $$2.00$$ moles of an ideal gas?

Accepted Answer

$$44.8\ \mathrm{L}$$

Question 13

A mixture contains $$2.0\ \mathrm{mol} of$$ $$\mathrm{O}_2$$ and $$3.0\ \mathrm{mol} of$$ $$\mathrm{N}_2 in a$$ $$10.0\ \mathrm{L}$$ container at $$300\ \mathrm{K}. $$What is the partial pressure of $$\mathrm{O}_2$$? ($$R = 0.0821\ \mathrm{L\ atm\ $$mol^{-1}$$\ K$$^{-1}$$})$$

Accepted Answer

$$4.92\ \mathrm{atm}$$

Question 14

Which of the following is NOT a postulate of the kinetic molecular theory of gases?

Accepted Answer

Gas particles lose energy when they collide with each other.

Question 15

Which statement best describes how the Van der Waals equation accounts for non-ideal behavior in gases?

Accepted Answer

It corrects for intermolecular attractions and the finite volume of gas particles.

Question 16

Which of the following best explains how gases create pressure?

Accepted Answer

Gas particles collide with the walls of their container, exerting force per unit area.

Question 17

A $$5.00\ \mathrm{g}$$ sample of a substance absorbs $$100.0\ \mathrm{J} of $$heat, causing its temperature to rise from $$20.0\ ^\circ\mathrm{C} to$$ $$40.0\ ^\circ\mathrm{C}. $$What is the specific heat of the substance?

Accepted Answer

$$1.00\ \mathrm{J/g\ ^\circ C}$$

Question 18

A weather balloon contains $$10.0\ \mathrm{L} of $$helium at $$1.00\ \mathrm{atm}$$ and $$300\ \mathrm{K}. If $$the balloon rises to a region where the pressure is $$0.500\ \mathrm{atm}$$ and the temperature is $$250\ \mathrm{K}$$, what will be the new volume of the balloon?

Accepted Answer

$$24.0\ \mathrm{L}$$

Question 19

Which of the following is the correct definition of heat capacity?

Accepted Answer

The amount of heat required to raise the temperature of an object by $$1\ ^\circ\mathrm{C}.$$

Question 20

A reaction has a standard enthalpy of formation $$\Delta H_f^\circ of$$ $$-393.5\ \mathrm{kJ/mol}$$ for $$\mathrm{CO}_2(g). $$What does this value represent?

Accepted Answer

The enthalpy change when $$1$$ mole of $$\mathrm{CO}_2(g) is $$formed from its elements in their standard states.

General Chemistry Review: Thermochemistry and Gas Laws

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