0.1M HCl and 0.1M H₂SO₄ each of volume 2mL are mixed and the volume is made up to 6mL by adding 2mL of 0.01N NaCl solution. The pH of the resulting mixture is

To determine the pH of the resulting mixture, we need to calculate the total concentration of hydrogen ions ([H⁺]) contributed by each component.

Step 1: Calculate moles of H⁺ from each acid

• HCl: 0.1 M concentration means 0.1 moles per liter. For 2 mL (0.002 L):

  Moles of H⁺ from HCl = 0.1 M × 0.002 L = 0.0002 moles

• H₂SO₄: 0.1 M concentration means 0.1 moles per liter. Sulfuric acid (H₂SO₄) dissociates completely in its first ionization, providing 2 moles of H⁺ per mole of H₂SO₄. For 2 mL (0.002 L):

  Moles of H⁺ from H₂SO₄ = 0.1 M × 0.002 L × 2 = 0.0004 moles

Step 2: Calculate total moles of H⁺

Total moles of H⁺ = Moles from HCl + Moles from H₂SO₄

Total moles of H⁺ = 0.0002 + 0.0004 = 0.0006 moles

Step 3: Calculate total volume of the mixture

Total volume = 2 mL HCl + 2 mL H₂SO₄ + 2 mL NaCl solution = 6 mL = 0.006 L

Step 4: Calculate concentration of H⁺ in the mixture

[H⁺] = Total moles of H⁺ / Total volume

[H⁺] = 0.0006 moles / 0.006 L = 0.1 M

Step 5: Calculate pH

pH = -log₁₀([H⁺])

pH = -log₁₀(0.1)

pH = 1

Therefore, the pH of the resulting mixture is 1.0.

Answer: 1.0