What is the percent yield of a reaction in which 200. g of phosphorus trichloride reacts with excess water to form 138 g of HCl and aqueous phosphorous acid (H3PO3)?
write the equation
figure the moles of phosphorus trichloride
the equation tells you how many moles of HCl to expect
convert that to grams
divide 138 by the expected mass * 100%
calculate mass
To calculate the percent yield, we need to compare the actual yield (138 g of HCl and aqueous phosphorous acid) with the theoretical yield. The theoretical yield is the maximum amount of product that can be obtained based on the balanced chemical equation.
First, let's write the balanced chemical equation for the reaction:
PCl3 + 3H2O → H3PO3 + 3HCl
From the balanced equation, we can see that the molar ratio between PCl3 and H3PO3 is 1:1. Therefore, the theoretical yield of H3PO3 is also 200 g.
Now, let's calculate the percent yield:
Percent Yield = (Actual Yield / Theoretical Yield) * 100
Actual Yield = 138 g
Theoretical Yield = 200 g
Percent Yield = (138 g / 200 g) * 100
Percent Yield = 0.69 * 100
Percent Yield = 69%
Therefore, the percent yield of the reaction is 69%.
To calculate the percent yield of a reaction, we need to compare the actual yield of the product to the theoretical yield.
Step 1: Determine the balanced chemical equation for the reaction:
PCl3 + 3H2O → H3PO3 + 3HCl
Step 2: Calculate the molar masses of the substances involved:
- Molar mass of PCl3 = 137.33 g/mol
- Molar mass of HCl = 36.46 g/mol
- Molar mass of H3PO3 = 82.0 g/mol
Step 3: Calculate the number of moles of PCl3:
Moles = mass / molar mass
Moles of PCl3 = 200 g / 137.33 g/mol = 1.456 mol
Step 4: Determine the limiting reagent:
The balanced equation tells us that the mole ratio of PCl3 to H3PO3 is 1:1. Therefore, 1.456 mol of PCl3 will react to form 1.456 mol of H3PO3.
Step 5: Calculate the theoretical yield of H3PO3:
Theoretical yield = moles of limiting reagent × molar mass of H3PO3
Theoretical yield = 1.456 mol × 82.0 g/mol = 119.392 g
Step 6: Calculate the percent yield:
Percent yield = (actual yield / theoretical yield) × 100
Percent yield = (138 g / 119.392 g) × 100 = 115.6%
Therefore, the percent yield of the reaction is 115.6%.