Q: A buffer solution is prepared by mixing acetic acid ($$\text{CH}_3\text{COOH}) $$and sodium acetate ($$\text{CH}_3\text{COONa}). $$Which equation best describes the pH of this buffer?

$$\text{pH} = \text{p}K_a + \log \left( \frac{[\text{CH}_3\text{COONa}]}{[\text{CH}_3\text{COOH}]} \right)$$

Q: Which of the following changes will increase the solubility of $$\text{CaF}_2 in $$water?

Adding hydrochloric acid ($$\text{HCl}).$$

Question 1

A chemical reaction is carried out in a coffee-cup calorimeter at constant pressure. The temperature of the solution increases by 3.5 °C when 0.50 g of a substance is dissolved. Which of the following best describes the sign and meaning of $$\Delta H$$ for this process?

Accepted Answer

$$\Delta H is $$negative; the process is exothermic.

Question 2

Which of the following statements about reaction mechanisms is correct?

Accepted Answer

The slowest elementary step in a mechanism determines the overall reaction rate.

Question 3

A reaction has the following rate law: $$	ext{rate} = k[	ext{NO}_2]^2[	ext{Cl}_2]. If $$the concentration of $$	ext{NO}_2 is $$doubled and $$	ext{Cl}_2 is $$halved, by what factor does the rate change?

Accepted Answer

The rate increases by a factor of 2.

Question 4

At equilibrium, which of the following is always true for a chemical reaction?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 5

A buffer solution is prepared by mixing acetic acid ($$	ext{CH}_3	ext{COOH}) $$and sodium acetate ($$	ext{CH}_3	ext{COONa}). $$Which equation best describes the pH of this buffer?

Accepted Answer

$$	ext{pH} = 	ext{p}K_a + \log \left( \frac{[	ext{CH}_3	ext{COONa}]}{[	ext{CH}_3	ext{COOH}]} ight)$$

Question 6

Which of the following changes will increase the solubility of $$	ext{CaF}_2 in $$water?

Accepted Answer

Adding hydrochloric acid ($$	ext{HCl}).$$

Question 7

Which of the following best explains why water has a higher boiling point than methane ($$	ext{CH}_4$$)?

Accepted Answer

Water forms hydrogen bonds, while methane only has London dispersion forces.

Question 8

A solution is prepared by dissolving 10.0 g of glucose ($$	ext{C}_6	ext{H}_{12}	ext{O}_6) in 90.0 g of $$water. Which of the following best describes the resulting solution?

Accepted Answer

It is an unsaturated solution.

Question 9

Which of the following salts will have the highest molar solubility in water at 25°C, assuming all have similar $$K_{sp}$$ values?

Accepted Answer

$$	ext{NaCl}$$

Question 10

Which of the following statements about entropy ($$\Delta S) is $$correct?

Accepted Answer

A gas has higher entropy than a solid at the same temperature.

Question 11

A galvanic cell is constructed using a zinc electrode in a $$	ext{ZnSO}_4$$ solution and a copper electrode in a $$	ext{CuSO}_4$$ solution. Which of the following correctly identifies the anode and the direction of electron flow?

Accepted Answer

Zinc is the anode; electrons flow from zinc to copper.

Question 12

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It lowers the activation energy, increasing the reaction rate.

Question 13

A student adds 0.10 mol of $$	ext{HCl} to 1.0 L of a $$buffer solution containing 0.50 mol of acetic acid and 0.50 mol of sodium acetate. What will happen to the pH of the solution?

Accepted Answer

The pH will decrease slightly.

Question 14

Which of the following is the correct expression for the equilibrium constant $$K_c$$ for the reaction $$	ext{N}_2(g) + 3	ext{H}_2(g) ightleftharpoons 2	ext{NH}_3(g)$$?

Accepted Answer

$$K_c = \frac{[	ext{NH}_3]^2}{[	ext{N}_2][	ext{H}_2]^3}$$

Question 15

Which of the following best explains why increasing the temperature increases the rate of a chemical reaction?

Accepted Answer

It increases the number of effective collisions between reactant molecules.

Question 16

A solution is prepared by mixing 100 mL of 0.10 M $$	ext{NaOH}$$ with 100 mL of 0.10 M $$	ext{HCl}. $$What is the pH of the resulting solution?

Accepted Answer

pH = 7

Question 17

Which of the following statements about the Gibbs free energy change ($$\Delta G) is $$correct?

Accepted Answer

$$\Delta G is $$zero at equilibrium.

Question 18

A patient is given an intravenous solution that is hypertonic relative to their blood plasma. What is the most likely effect on the patient's red blood cells?

Accepted Answer

The cells will shrink due to water leaving the cells.

Question 19

Which of the following best describes the relationship between the standard cell potential ($$E^\circ_{cell}) $$and the equilibrium constant ($$K) $$for a redox reaction?

Accepted Answer

$$E^\circ_{cell} is $$positive when $$K \u003e 1.$$

CHEM 2080: General Chemistry II – Course Syllabus and Topic Overview

Guida di studio - Domande di pratica

Study guide - Flashcard