Weak acids and Ka Quiz
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5 questions, one answer each
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1. Which expression gives Ka for the weak acid HA?
- A. [HA] / [H⁺][A⁻]
- B. [H⁺][A⁻]
- C. [H⁺][A⁻] / [HA]
- D. [H⁺]² / [A⁻]
2. An acid has Ka = 1.00 × 10⁻⁵ mol dm⁻³. What is its pKa?
- A. 5.00
- B. –5.00
- C. 9.00
- D. 1.00
3. What is the pH of 0.0500 mol dm⁻³ of a weak acid with Ka = 2.00 × 10⁻⁵ mol dm⁻³?
- A. 1.30
- B. 2.00
- C. 4.70
- D. 3.00
4. Which acid is the strongest?
- A. pKa 4.76
- B. pKa 3.75
- C. pKa 9.25
- D. pKa 6.35
5. What is an assumption made in weak acid pH calculations?
- A. [HA] = 0 at equilibrium
- B. [H⁺] = [A⁻]
- C. [H⁺] = [HA]
- D. Ka = 1