Final answer:
Solutions A (100 cm³ of 0.1 M HCl) and B (50 cm³ of 0.2 M HNO₃) both provide the same number of hydrogen ions as in 50 cm³ of 0.1 M sulfuric acid, which is 0.01 mol. Solution C has double the number, and solution D has a different amount due to the triprotic nature of phosphoric acid.
Step-by-step explanation:
The student asked which solution has the same number of hydrogen ions as in 50 cm³ of 0.1 mol dm⁻³ sulfuric acid (H₂SO₄). Because sulfuric acid is a diprotic acid, it releases two hydrogen ions per molecule. Therefore, the number of moles of H+ ions in 50 cm³ of a 0.1 M sulfuric acid solution is 0.1 mol/dm³ × 0.050 dm³ × 2 = 0.01 mol. Let's analyze each option:
- A) 100 cm³ of 0.1 mol dm⁻³ hydrochloric acid (HCl) would have 0.01 mol of H+ ions since HCl is monoprotic (0.1 mol/dm³ × 0.100 dm³ = 0.01 mol).
- B) 50 cm³ of 0.2 mol dm⁻³ nitric acid (HNO₃) would have 0.01 mol of H+ ions, as HNO₃ is also monoprotic (0.2 mol/dm³ × 0.050 dm³ = 0.01 mol).
- C) 100 cm³ of 0.2 mol dm⁻³ sulfuric acid would have 0.02 mol of H+ ions, which is double the required amount (0.2 mol/dm³ × 0.100 dm³ × 2 = 0.04 mol).
- D) 50 cm³ of 0.1 mol dm⁻³ phosphoric acid (H₃PO₄) would not have the same number of H+ ions because phosphoric acid is triprotic, and the amount of H+ would be different (0.1 mol/dm³ × 0.050 dm³ × 3 ≠ 0.01 mol).
Therefore, solutions A and B both have the same number of H+ ions as the original sulfuric acid solution.