Question

Bleaching powder is made from contacting chlorine gas with showered calcium hydroxide in a rotating steel cylinder. The chemical reaction is

Ca(OH)2 + Cl2-----> CaOCl2 + H2O

You have 100 lb of Chlorine and 150 lb of calcium hydroxide.

a) Determine the limiting reactant

b) Assuming 90% conversion, calculate the outlet concentration and the amount of bleaching powder.

Answer 1

Mass of Chlorine = 100 lbs = 45.3592 Kg = 45359.2 gms

Molar mass of Chlorine = 71 gm/mol

Number of moles of Chlorine = 45359.2/Molar mass of Chlorine = 45359.2/71 = 638.86 moles

Mass of Ca(OH)2 = 150 lbs = 68.0389 Kg = 68038.9 gms

Molar mass of Ca(OH)2 = 40 + 2 * 17 = 74 gm/mol

Number of moles of Ca(OH)2 = 68038.9/Molar mass of Ca(OH)2 = 68038.9/74 = 919.44 moles

a) 1 mole of Ca(OH)2 will react with 1 mole of Cl2

Hence the limiting reagent in the reaction = Cl2

b) Amount of bleaching powder = number of moles of Cl2 * 90/100 = 638.86 * 0.9 = 574.974 moles

Molar mass of CaOCl2 = 40 + 16 + 2 * 35.5 = 56 + 71 = 127 gm/mol

Mass of CaOCl2 produced = 574.974 moles * 127 gm/mol = 73021.698 gms