The mass of sulfuric acid ( H ₂ SO ₄ ) required to prepare 200 mL of an aqueous solution with a pH of 2 is _____ mg . (Nearest integer) Assume complete dissociation of the acid. (Molar mass of H ₂ SO ₄ = 98 g mol ⁻¹ )

Step-by-step solution

Given, pH = 2 [ H ^+] = 10⁻² M Sulfuric acid is a strong dibasic acid, dissociating completely as: H ₂ SO ₄ 2 H ^+ + SO ₄²⁻ Therefore, the concentration of H ₂ SO ₄ is: [ H ₂ SO ₄] = [ H ^+] 2 = 10⁻² 2 = 5 10⁻³ M Number of moles of H ₂ SO ₄ required for 200 mL ( 0.2 L ) of solution: n = M V = 5 10⁻³ 0.2 = 10⁻³ moles Mass of H ₂ SO ₄ required: Mass = n Molar mass = 10⁻³ 98 g = 0.098 g Converting to milligrams: Mass in mg = 0.098 1000 = 98 mg Answer: 98