Question

600 mL of 0.04 M HCl is mixed with 400 mL of 0.02 M H₂SO₄. Find out the pH of resulting solution (Nearest integer).

Answer 1

Correct Answer: 1.4

To calculate the pH of the resulting solution, we need to find the total moles of H⁺ ions from both the acids, HCl and H₂SO₄, and then determine the concentration of H⁺ ions in the mixed solution.

Step 1: Calculate moles of H⁺ from HCl

Moles of HCl = M × V = 0.04 M × 0.600 L = 0.024 moles of H+

Step 2: Calculate moles of H⁺ from H₂SO₄

Since H₂SO₄ is a strong acid and dissociates to give 2 moles of H⁺ ions per mole of H₂SO₄, the moles of H⁺ from H₂SO₄ will be:

Moles of H+ = 0.02 M × 0.400 L × 2 = 0.016 moles of H+

Step 3: Calculate total moles of H⁺ in the solution

Total moles of H+ = 0.024 + 0.016 = 0.040 moles of H+

Step 4: Calculate the final volume of the solution

Total volume = 600 mL + 400 mL = 1000 mL = 1 L

Step 5: Calculate the concentration of H⁺ ions

[H+] = Total moles of H+ / Total volume = 0.040 moles / 1 L = 0.040 M

Step 6: Calculate the pH of the solution

pH = -log [H+] = -log (0.040) = 1.4