Ionic Equilibrium

Which of the following is a weak acid?

• HF

• HCl

• HBr

• HI

In the reaction above, the Brönsted-Lowry acids are

• H₂O and OH^-

• HSO₄^- and OH^-

• H₂O and H₂SO₄

• HSO₄^- and H₂SO₄

The solution with the lowest pH is

• 1.0M HBr

• 1.0M HCN

• 1.0M HCOOH

• 1.0M CH₃COOH

Solutions of each of the hypothetical acids in the following table are prepared with an initial concentration of 0.100 M. Which of the four solutions will have the lowest pH and be most acidic?

• HA

• HB

• HC

• HD

Calculate the approximate [H₃O⁺] concentration in a 0.220 M solution of hypochlorous acid.

K_a for HOCl = 3.0 x 10^-8.

• 1.7 x 10^-4

• 3.7 x 10^-4

• 8.1 x 10^-5

• 1.4 x 10^-7

In a 0.0100 M solution of a hypothetical weak acid HW, it is found that the [H₃O+] = 2.50 x 10^-3 M. K_a for the acid is:

• 6.25 x 10^-4

• 8.33 x 10^-4

• 6.25 x 10^-2

• 2.50 x 10^-1

Boric acid frequently is used as an eyewash to treat eye infections. The pH of a 0.050 M solution of boric acid is 5.28. What is the Ka value of the boric acid?

• 5.25 × 10^–6

• 5.51 × 10^–10

• 5.43 × 10^–8

• 5.33 × 10^–12

A 0.100 M solution of a monoprotic weak acid has a pH of 3.00. What is the pKa of this acid?

• 5.00

• 3.00

• 9.99

• 6.00

Which of the following combinations cannot produce a buffer solution?

• 25cm³ 0.100 moldm^-3 CH₃CH₂COOH(aq) and 25 cm³ 0.100 mol CH₃CH₂COONa

• 50cm³ 0.100 moldm^-3 CH₃CH₂COOH(aq) and 25 cm³ 0.100 mol NaOH

• 50 cm³ 0.100 moldm^-3 NH₃ (aq) and 50 cm³ 0.100 moldm^-3 HCl(aq)

• 50 cm³ 0.100 moldm^-3 NH₃ (aq) and 50 cm³ 0.100 moldm^-3 NH₄Cl(aq)

A buffer solution contains 0.36 M sodium acetate (CH₃COONa) and 0.45 M acetic acid (CH₃COOH), pKa = 4.8. What is the pH of this buffer solution?

• 4.7

• 5.2

• 3.8

• 6.1