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Percentage Yield Formula

Reactants often yield quantities of products that are less than those calculated on the basis of the formulated chemical reaction. The percent yield formula is used to determine the percentage of the theoretical yield that was formed in a reaction.

The ideal amount of product is called the theoretical yield and it is obtained by working a stoichiometry problem. Measuring the amount of product formed gives us the actual yield. From the ratio of the actual yield to the theoretical yield we can calculate the percentage yield.

Percentage yield = $\frac{actual yield}{theoretical yield}$ $\times$ 100%

The amount of product actually made compared with the maximum calculated yield is called the percentage yield.
 

Percentage Yield Solved Problems

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Some of the solved problems based on Percentage Yield Formula are given below.

Question 1: During a chemical reaction 0.6 g of product is made. The maximum calculated yield is 2.4 g. What is the percentage yield of this reaction?

Solution:
Substitute the values in the corresponding formula

Percentage yield = $\frac{actual yield}{theoretical yield}$ $\times$ 100%

Percentage yield = $\frac{0.6}{1.4}$ $\times$ 100%

Percentage yield = 42.9%

The percentage yield of this reaction is 25%, Scientist try to choose reactions with a high percentage yield or high atom economy. This contributes towards sustainable development by reducing waste.

Question 2:
If 11.2 g of Na reacts with 9.00 g of H2O and 0.400 g of H2 is formed, what is the percent yield of the reaction?

2Na + 2H2O $rightarrow$ 2NaOH + H2
The theoretical yield for this problem is 0.494g of H2.

Solution:
Substitute the values in the corresponding formula,

Percentage yield = $\frac{actual yield}{theoretical yield}$ $\times$ 100%

Percentage yield = $\frac{0.400}{0.494}$ $\times$ 100%

Percentage yield = 
81.0%