Answer to Question #113838 in General Chemistry for Jonathan

Question

If a 23.7 mL solution of H2SO4 has a concentration of 0.100 M, what is its pH? Also, how many grams of H2SO4 are in the solution?

Answer 1

Solution:

Sulfuric acid - H₂SO₄ - strong diprotic acid, completely dissociates into ions in solution.

The dissociation equation is written as:

H₂SO₄ = 2H⁺ + SO₄^2-

According to the equation: C_M(H₂SO₄) = [H⁺]/2.

[H⁺] = 2 × C_M(H₂SO₄) = 2 × (0.100 M) = 0.200 M

pH = -log[H⁺] = -log(0.200) = 0.69897 = 0.70

pH = 0.70

Molarity of H₂SO₄ = Moles of H₂SO₄ / Volume of solution

Moles of H₂SO₄ = n(H₂SO₄) = C_M(H₂SO₄) × V(solution)

n(H₂SO₄) = (0.100 M) × (0.0237 L) = 0.00237 mol

Moles of H₂SO₄ = Mass of H₂SO₄ / Molar mass of H₂SO₄

The molar mass of H₂SO₄ is 98.079 g/mol.

Mass of H₂SO₄ = m(H₂SO₄) = n(H₂SO₄) × M(H₂SO₄)

m(H₂SO₄) = (0.00237 mol) × (98.079 g/mol) = 0.2324 g

Mass of H₂SO₄ is 0.2324 g

Answer:

pH = 0.70

0.2324 grams of H₂SO₄ are in the solution.