Question 1

Which of the following best describes the role of intermolecular forces in determining the boiling point of a substance?

Accepted Answer

Stronger intermolecular forces result in a higher boiling point because more energy is required to separate the molecules.

Question 2

A sample of gas is contained in a 2.0 L vessel at 300 K and 1.0 atm. If the temperature is increased to 600 K and the volume is doubled, what will be the new pressure, assuming ideal gas behavior?

Accepted Answer

$$P_2$$ = \frac{$$P_1$$ $$T_2$$ $$V_1$$}{$$T_1$$ $$V_2$$} = \frac{1.0 	imes 600 	imes 2.0}{300 	imes 4.0} = 1.0$$ atm

Question 3

Which statement about entropy ($$S) is $$correct?

Accepted Answer

Entropy is a measure of the disorder or randomness of a system.

Question 4

Which of the following is the correct expression for the equilibrium constant $$K_c$$ for the reaction $$aA + bB \rightleftharpoons cC + dD$$?

Accepted Answer

$$K_c = \frac{[C]^c [D]^d}{[A]^a [B]^b}$$

Question 5

A buffer solution is made by mixing 0.10 mol of acetic acid ($$CH_3COOH) $$and 0.10 mol of sodium acetate ($$CH_3COONa) in 1.0 L of $$water. If the $$K_a of $$acetic acid is $$1.8 	imes 10$$^{-5}$$, what is the pH of the solution?

Accepted Answer

$$pH = pK_a + \log \left( \frac{[A^-]}{[HA]} \right) = 4.74 + \log(1) = 4.74$$

Question 6

Which of the following best explains why water has a relatively high boiling point compared to other group 16 hydrides?

Accepted Answer

Water molecules form hydrogen bonds, which are stronger than other intermolecular forces.

Question 7

For the reaction $$2NO_2(g) \rightarrow 2NO(g) + O_2$(g)$$, which of the following correctly describes the rate law if the reaction is first order in $$NO_2$$?

Accepted Answer

$$rate = k[NO_2$]$$

Question 8

Which of the following statements about catalysts is true?

Accepted Answer

Catalysts lower the activation energy, increasing the rate of reaction.

Question 9

A solution is prepared by dissolving 0.50 mol of $$NaCl in $$enough water to make 2.0 L of solution. What is the molarity of the solution?

Accepted Answer

$$0.25 M$$

Question 10

Which of the following is the correct balanced equation for the combustion of methane ($$CH_4$$)?

Accepted Answer

$$CH_4 + 2O_2$$ \rightarrow $$CO_2 + 2H_2O$

Question 11

Which of the following best describes the effect of increasing temperature on the rate of a chemical reaction?

Accepted Answer

The rate increases because more molecules have sufficient energy to overcome the activation energy barrier.

Question 12

Which of the following is the correct formula for calculating the standard cell potential ($$E^	ext{cell}) of a $$galvanic cell?

Accepted Answer

$$E^	ext{cell} = E^	ext{cathode} - E^	ext{anode}$$

Question 13

A 0.10 M solution of a weak acid has a pH of 3.0. What is the concentration of $$H^+$$ ions in the solution?

Accepted Answer

$$[H^+] = 1.0 	imes 10$$^{-3}$$ M

Question 14

Which of the following statements about the first law of thermodynamics is correct?

Accepted Answer

The total energy of an isolated system is constant.

Question 15

Which of the following is the correct expression for Gibbs free energy ($$\Delta G$$)?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 16

Which of the following is a correct statement about oxidation and reduction in a redox reaction?

Accepted Answer

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

Question 17

A student mixes 50.0 mL of 0.20 M $$HCl$$ with 50.0 mL of 0.20 M $$NaOH. $$What is the pH of the resulting solution?

Accepted Answer

pH = 7.00

Question 18

Which of the following best describes the effect of a common ion on the solubility of a sparingly soluble salt?

Accepted Answer

The common ion decreases the solubility of the salt due to Le Chatelier's principle.

Question 19

Which of the following is the correct formula for the ideal gas law?

Accepted Answer

$$PV = nRT$$

CHEM 1110: Introduction to Physical Chemistry – Course Overview and Key Concepts

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