Buffer solutions Quiz

1. A buffer contains 0.200 mol dm⁻³ HA and 0.200 mol dm⁻³ A⁻ with pKₐ 5.10. What is its pH?

• A. 5.10
• B. 2.55
• C. 8.90
• D. 7.00

2. Which mixture is a buffer?

• A. Equal amounts of HCl and NaCl
• B. Equal amounts of CH₃COOH and NaOH
• C. 2 mol CH₃COOH + 1 mol NaOH
• D. 1 mol HCl + 1 mol NaOH

3. Which species in the ethanoic acid buffer removes added H⁺?

• A. CH₃COOH
• B. CH₃COO⁻
• C. Na⁺
• D. H₂O

4. A buffer has $[HA]$ = 0.100 mol dm⁻³ and $[A^-]$ = 0.400 mol dm⁻³, with $K_a$ = 2.0 × 10⁻⁵ mol dm⁻³. What is $[H^+]$?

• A. 8.0 × 10⁻⁵ mol dm⁻³
• B. 1.0 × 10⁻⁷ mol dm⁻³
• C. 2.0 × 10⁻⁵ mol dm⁻³
• D. 5.0 × 10⁻⁶ mol dm⁻³

5. Which equation shows how blood buffer deals with excess H⁺?

• A. H⁺ + H₂CO₃ → HCO₃⁻
• B. OH⁻ + HCO₃⁻ → H₂CO₃
• C. H⁺ + HCO₃⁻ → H₂CO₃
• D. H₂CO₃ + H₂O → H⁺