Question

A plant makes liquid carbon dioxide by treating a limestone with commercial sulfuric acid. The limestone analyzes 65.8% calcium carbonate, 25.7% magnesium carbonate and the rest silica. The acid used was 89.5% sulfuric acid with rest being water. Calculate the pounds of acid required per ton of limestone treated.

Answer 1

Mass of limestone = 1000 kg

Mass of CaCO₃ = 0.658 x 1000 = 658 kg

Mass of MgCO₃ = 0.257 x 1000 = 257 kg

Mass of Silica = 1000 - 658 - 257 = 85 kg

Molar mass of CaCO₃ = 100.08 g/mol

Moles of CaCO₃ = (658) / 100.08 = 6.574 kmol

Molar mass of MgCO₃ = 84.314 g/mol

Moles of MgCO₃ = (257) / 84.314 = 3.048 kmol

Moles of H₂SO₄ required based on the above reactions = 6.574 + 3.048 = 9.622 kmol

Molar Mass of H₂SO₄ = 98.079 kg/kmol

Mass of H₂SO₄ = 9.622 x 98.079 = 943.716 kg

Purity of H₂SO₄ = 89.5 %

Mass of acid required to treat limestone = 943.716 / 0.895 = 1054.43 kg

1 kg = 2.20462 lb

Mass of acid required to treat limestone = 1054.43 x 2.20462 = 2324.62 lb