Q: Which of the following is the correct expression for the enthalpy change of a reaction using standard enthalpies of formation?

$$\Delta H^\circ_{rxn} = \sum n \Delta H^\circ_f (\text{products}) - \sum n \Delta H^\circ_f (\text{reactants})$$

Question 1

A solution is prepared by dissolving 10.0 g of NaCl in enough water to make 500 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 2

Which of the following best describes a strong electrolyte?

Accepted Answer

A substance that completely dissociates into ions in aqueous solution

Question 3

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of Na$$_2SO$_4$$ and BaCl$$_2$$?

Accepted Answer

$$\mathrm{Ba$$^{2+}$$ (aq) + SO_4$^{2-} (aq) \rightarrow $$BaSO_4$$ (s)}$$

Question 4

A 2.00 L container holds a mixture of nitrogen and oxygen gases at a total pressure of 1.50 atm. If the partial pressure of nitrogen is 1.00 atm, what is the partial pressure of oxygen?

Accepted Answer

$$0.50\ \mathrm{atm}$$

Question 5

Which of the following statements about the ideal gas law is correct?

Accepted Answer

It assumes that gas particles have negligible volume and no intermolecular forces.

Question 6

A sample of gas occupies 4.00 L at 1.00 atm and 300 K. What will be its volume at 2.00 atm and 300 K, assuming ideal behavior?

Accepted Answer

$$2.00\ \mathrm{L}$$

Question 7

Which of the following best explains why real gases deviate from ideal behavior at high pressures?

Accepted Answer

The volume of gas particles becomes significant compared to the container volume.

Question 8

Which of the following equations represents the first law of thermodynamics?

Accepted Answer

$$\Delta U = q + w$$

Question 9

A chemical reaction has $$\Delta H = -150\ \mathrm{kJ}$$ and $$\Delta S = -200\ \mathrm{J/K}. At $$what temperature (in K) does the reaction become non-spontaneous? ($$\Delta G = \Delta H - T \Delta S)$$

Accepted Answer

$$750\ \mathrm{K}$$

Question 10

Which of the following is an example of an exothermic process?

Accepted Answer

Combustion of methane in air

Question 11

Which of the following best describes a state function?

Accepted Answer

A property that depends only on the current state of the system, not on the path taken

Question 12

Which of the following is the correct expression for the enthalpy change of a reaction using standard enthalpies of formation?

Accepted Answer

$$\Delta H^\circ_{rxn} = \sum n \Delta H^\circ_f (	ext{products}) - \sum n \Delta H^\circ_f (	ext{reactants})$$

Question 13

A 50.0 g sample of water is heated from 25.0 $$^\circC to 75.0$$ $$^\circC. $$How much heat is absorbed? (Specific heat of water = $$4.18\ \mathrm{J/g\cdot K})$$

Accepted Answer

$$10,450\ \mathrm{J}$$

Question 14

Which of the following best explains why CO$$_2 is $$considered a greenhouse gas?

Accepted Answer

It absorbs infrared radiation emitted by the Earth's surface, trapping heat in the atmosphere.

Question 15

Which of the following is a renewable energy alternative that can help reduce atmospheric CO$$_2$$ levels?

Accepted Answer

Solar power

Question 16

Which of the following is the correct balanced equation for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$\mathrm{C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O}$$

Question 17

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 18

A sample of gas at 300 K and 1.00 atm occupies 2.00 L. If the temperature is increased to 600 K at constant pressure, what is the new volume?

Accepted Answer

$$4.00\ \mathrm{L}$$

Question 19

Which of the following best describes the difference between heat capacity and specific heat?

Accepted Answer

Heat capacity is the amount of heat required to raise the temperature of an object by 1 K, while specific heat is the amount of heat required to raise the temperature of 1 g of a substance by 1 K.

General Chemistry Study Guide: Solutions, Gases, and Thermochemistry

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