Question 1
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
Question 2
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
Question 3
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
Question 4
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
Question 5
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
Question 6
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]
Question 7
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]
Question 8
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]
Question 9
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]
Question 10
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]