Wazari Exam (Iraq Baccalaureate) - Scientific Branch · Chemistry

Acids, equilibrium and electrochemistry

22 practice questions, each with the answer and an explanation.

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All 22 questions

  1. What is the pH of a mol/L solution of hydrochloric acid at 25 °C?
  2. What is the pH of a mol/L solution of sodium hydroxide at 25 °C?
  3. What is the pH of a mol/L solution of hydrochloric acid at 25 °C?
  4. What is the pH of a mol/L solution of hydrochloric acid at 25 °C?
  5. A strong acid of pH 3 is diluted until its volume is 100 times larger. What is the new pH, approximately?
  6. A strong acid of pH 4 is diluted until its volume is 10 times larger. What is the new pH, approximately?
  7. A strong acid of pH 1 is diluted until its volume is 100 times larger. What is the new pH, approximately?
  8. 50 mL of 0.1 mol/L HCl is mixed with 50 mL of 0.06 mol/L NaOH (volumes are additive, 25 °C). What is the approximate pH of the mixture? (log 2 = 0.30)
  9. 100 mL of 0.05 mol/L HCl is mixed with 100 mL of 0.03 mol/L NaOH (volumes are additive, 25 °C). What is the approximate pH of the mixture?
  10. 50 mL of 0.12 mol/L HCl is mixed with 50 mL of 0.02 mol/L NaOH (volumes are additive, 25 °C). What is the approximate pH of the mixture? (log 5 = 0.70)
  11. 100 mL of 0.04 mol/L HCl is mixed with 100 mL of 0.02 mol/L NaOH (volumes are additive, 25 °C). What is the approximate pH of the mixture?
  12. At equilibrium for N₂(g) + 3H₂(g) ⇌ 2NH₃(g) the concentrations are [N₂] = 1 mol/L, [H₂] = 3 mol/L and [NH₃] = 6 mol/L. What is ?
  13. At equilibrium for N₂(g) + 3H₂(g) ⇌ 2NH₃(g) the concentrations are [N₂] = 2 mol/L, [H₂] = 2 mol/L and [NH₃] = 8 mol/L. What is ?
  14. What is the standard cell potential of the Zn/Cu galvanic cell if the standard electrode potentials are -0.76 V and 0.34 V?
  15. What is the standard cell potential of the Fe/Cu galvanic cell if the standard electrode potentials are -0.44 V and 0.34 V?
  16. What is the standard cell potential of the Zn/Pb galvanic cell if the standard electrode potentials are -0.76 V and -0.13 V?
  17. What charge is needed to deposit 0.1 mol of copper from a Cu²⁺ solution? (F = 96 500 C/mol)
  18. What charge is needed to deposit 0.2 mol of copper from a Cu²⁺ solution? (F = 96 500 C/mol)
  19. What charge is needed to deposit 0.05 mol of copper from a Cu²⁺ solution? (F = 96 500 C/mol)
  20. What charge is needed to deposit 0.25 mol of copper from a Cu²⁺ solution? (F = 96 500 C/mol)
  21. Given (a) C(s) + O₂(g) → CO₂(g), ΔH = -394 kJ; (b) CO(g) + ½O₂(g) → CO₂(g), ΔH = -283 kJ. What is ΔH for C(s) + ½O₂(g) → CO(g)?
  22. Given (a) S(s) + O₂(g) → SO₂(g), ΔH = -297 kJ; (b) SO₂(g) + ½O₂(g) → SO₃(g), ΔH = -99 kJ. What is ΔH for S(s) + 3/2 O₂(g) → SO₃(g)?

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