A Level Chemistry - Acids & Bases - pH <-> Ka

Given a weak acid with a K_a of 1.8 x 10^-5, calculate the pH of a 0.10 M solution.

• 2.87

• 3.75

• 4.74

• 5.11

The pH of a 0.025 M acetic acid solution is 4.76. What is the K_a of acetic acid to 2SF?

• 1.8 x 10^-5

• 4.5 x 10^-7

• 5.0 x 10^-6

• 1.3 x 10^-8

Find the pH of a solution with a K_a of 1.3 x 10^-3 and a concentration of 0.15 M.

• 1.92

• 1.85

• 3.15

• 4.00

A solution has a pH of 5. What is the concentration of H⁺ ions?

• 1 x 10^-5 M

• 5 x 10^-5 M

• 1 x 10^-3 M

• 1 x 10^-6 M

What is the relationship between K_a and pH for a weak acid?

• As K_a increases, pH increases.

• As K_a increases, pH decreases.

• K_a and pH are unrelated.

• K_a and pH both increase together.

The pH of a 0.1 M benzoic acid solution is 2.87. Calculate the K_a.

• 6.5 x 10^-4

• 1.8 x 10^-5

• 2.1 x 10^-7

• 4.9 x 10^-5

Which of the following describes a weak acid?

• Low K_a, high pH

• Low K_a, low pH

• High K_a, low pH

• High K_a, high pH

What is the pH of a solution, where [H⁺] = 1 x 10^-4 M?

• 2

• 4

• 6

• 8

A weak acid has a K_a of 4.5 x 10^-6. If the concentration of the acid is 0.05 M, what is the pH?

• 2.3

• 3.1

• 3.3

• 4.8

If the pH of a solution is 3.40, what is the concentration of H⁺ ions?

• 3.98 x 10^-4 M

• 4.00 x 10^-4 M

• 1.20 x 10^-5 M

• 2.51 x 10^-3 M