Question

Consider the balanced equation.


PCl3 + 3H2O Right arrow. H3PO3 + 3HCl


What is the percent yield of HCl if 42.0 g of HCl are produced from the reaction of 62.0 g of PCl3?

28.4%
72.8%
85.0%
93.5%

Answer 1

Balanced equation: PCl3 + 3 H2O → H3PO3 + 3 HCl

1) Moles PCl3 = 62.0 g / 137.33 g·mol⁻¹ = 0.4516 mol (molar mass PCl3 ≈ 30.974 + 3×35.453 = 137.33 g·mol⁻¹).

2) Moles HCl theoretical = 3 × 0.4516 = 1.3548 mol.

3) Mass HCl theoretical = 1.3548 mol × 36.46 g·mol⁻¹ = 49.43 g (molar mass HCl ≈ 1.008 + 35.453 = 36.46 g·mol⁻¹).

4) Percent yield = (actual / theoretical) × 100% = (42.0 / 49.43) × 100% = 84.97% ≈ 85.0%.

Answer: 85.0%