18.2 Calculations Involving Acids and Bases

Which of the following statements is true regarding the relationship between Ka, Kb, and Kw for a conjugate acid-base pair?

A. Ka x Kb = Kw

B. Ka + Kb = Kw

C. Ka / Kb = Kw

D. Ka - Kb = Kw

Given that the Ka for a weak acid is 1.0 x 10^-5, what is the Kb for its conjugate base if Kw = 1.0 x 10^-14?

A. 1.0 x 10^-9

B. 1.0 x 10^-5

C. 1.0 x 10^-19

D. 1.0 x 10^-10

A strong acid is one that:

A. Has a low Ka value

B. Completely dissociates in water

C. Has a high Kb value

D. Partially dissociates in water

Which of the following is NOT a characteristic of a weak base?

A. It has a low Kb value

B. It partially dissociates in water

C. It has a high Ka value

D. It does not release all its hydroxide ions in water

If the Kb of ammonia (NH3) is 1.8 x 10^-5, what is the Ka of its conjugate acid (NH4+)?

A. 5.6 x 10^-10

B. 1.8 x 10^-5

C. 5.6 x 10^-20

D. 1.8 x 10^-10

a) Define the terms Ka and Kb in the context of acid-base chemistry. [2]

b) Given that the value of Kw is 1.0 x 10^-14 at 25°C, calculate the value of Kb for an acid with a Ka of 1.8 x 10^-5. [3]

a) Explain the relationship between the magnitude of Ka and the strength of an acid. [2]

b) A weak base B has a Kb of 2.5 x 10^-6. Predict the pH of a 0.1 M solution of this base at 25°C. [3]

a) Describe the difference between a Lewis acid and a Brønsted-Lowry acid. [3]

b) Given a weak acid HA with a Ka of 3.2 x 10^-4, determine whether the acid is strong or weak based on its dissociation constant. [2]

a) Describe how the strength of an acid can be predicted from its dissociation constant, Ka. [2]

b) A solution of a weak acid, HA, has a pH of 3.5. Calculate the concentration of H+ ions in the solution. [2]

c) If the concentration of HA in the solution is 0.1 M, determine its Ka value. [3]

a) Define a Lewis base and explain how it differs from a Brønsted-Lowry base. [3]

b) Given that Kw is 1.0 x 10^-14 at 25°C, and the Ka for an acid HA is 2.0 x 10^-6, calculate the Kb for its conjugate base A-. [2]

c) Would A- be considered a strong or weak base? Justify your answer. [2]