What is the percent yield of the reaction PCI3 ( g ) + 3H₂O ( 1 ) H3PO3 ( aq ) + 3HCl ( aq

Question

1. What is the percent yield of the reaction :

PCI3 ( g ) + 3H₂O ( 1 ) H3PO3 ( aq ) + 3HCl ( aq )

where 20.0 g of phosphorus trichloride react with excess water to form 11.2 g of HCI and phosphorous acid ( H3PO3 )?

Answer 1

To find the percent yield, we first need to find the theoretical yield. To find the theoretical yield, we use the stoichiometry of the balanced equation.

PCl3 + 3H2O ==> H3PO3 + 3HCl ... balanced equation (1 PCl3 makes 1 H3PO3)

moles PCl3 = 20.0 g x 1 mol PCl3 / 137 g = 0.1459 moles

moles H3PO3 = 0.1459 moles (1:1 mole ratio)

Theoretical yield (in g) H3PO3 = 0.1459 mols H3PO3 x 81.99 g/mol = 11.96 g

Percent yield = actual yield / theoretical yield (x100%)

% yield = 11.2 g / 11.96 g (x100%) = 93.6% (3 sig. figs.)