Question

4PCl3 → P4 + 6Cl2. Balance the equation and determine the mass in grams of chlorine that would be formed if 25 grams of PCl3 (molecular mass = 137.32 g/mol) decompose.

Answer 1

The equation is already balanced. Moles of PCl3 = 25/137.32 = 0.182 mole. According to stoichiometry, 4 moles of PCl3 forms 6 moles of Cl2. Therefore, 0.182 moles of PCl3 will form = 6x0.182/4 = 0.273 mole of Cl2. Mass of Cl2 formed = moles of Cl2 x molar mass of Cl2 = 0.273x71 = 19.383 grams.