Difference Between Percent Yield and Percent Recovery

Key Difference – Percent Yield vs Percent Recovery
 

Percent yield is the amount of a compound obtained from a chemical synthesis reaction with respect to the theoretically expected amount. This is a percentage value. It is used to determine the efficiency of a chemical reaction. percent recovery is a term that is often used in organic chemistry regarding recrystallization processes. The percent recovery is the amount of pure compound with respect to the impure compound obtained from the chemical synthesis. The key difference between percent yield and percent recovery is that percent yield is calculated as a ratio between actual yield and theoretical yield whereas percent recovery is calculated as the ratio between the pure compound and initial compound.

CONTENTS

1. Overview and Key Difference
2. What is Percent Yield
3. What is Percent Recovery
4. Similarities Between Percent Yield and Percent Recovery
5. Side by Side Comparison – Percent Yield vs Percent Recovery in Tabular Form
6. Summary

What is Percent Yield?

Percent yield is the ratio between percentages of actual yield and the theoretical yield of the final product obtained from chemical synthesis. Usually, the actual yield is smaller than that of the theoretical yield due to experimental errors such as incomplete chemical reactions, loss in the recovery of the product, etc. If the actual yield is equal to the theoretical yield, then the percent yield is 100%.

Percent Yield Calculation

Equation

The equation used to calculate the percent yield is as below.

Percent Yield = (Actual yield/ Theoretical yield) x 100%

Sometimes, the value of percent yield exceeds 100%. This means the product has an amount than expected from theoretical calculations. This is possible because there can be some other chemical reactions in the same reaction mixture that produce the same product. However, it can also be due to the presence of impurities.

Let’s take an example to understand the calculation of percent yield.

Ex: When CaCO₃ (16.0 g) is heated to thermal decomposition, 7.54 g of CaO was obtained.

Theoretical yield:

CaCO₃     →       CaO   +   CO₂

Stoichiometry between CaCO₃ and CaO is 1:1. Therefore, one mole of calcium carbonate should give 1 mole of calcium oxide. The molar mass of Calcium carbonate is 100 g/mol, and molar mass of calcium oxide is 56 g/mol.

If 100g of CaCO3 was burnt, it gives 56 g CaO. But in this experiment, 16.0 g was burnt. Then the amount of CaO should be given is,

Theoretical yield = (56 g /100 g) x 16 g = 8.96 g

Then the percent yield can be calculated as follows.

Percent yield = (7.54 g / 8.96 g) x 100% = 84.16 %

What is Percent Recovery?

Percent recovery is the amount of a product obtained after its synthesis and purification. The percent recovery can be used to determine the efficiency of the synthesis reaction. This term is often used in organic chemistry to determine the yield obtained from recrystallization.

The recrystallization process is used to obtain a purified product. Most of the times the final product given by chemical synthesis has many impurities. Therefore, purification is an essential step in organic synthesis reactions. In the recrystallization process, the compound to be purified is mixed with a suitable hot solvent and is stirred well. Then it is allowed to cool. During this cooling, the compound is precipitated. Then the percent recovery can be calculated.

Percent Recovery  Calculation

Equation

Percent Recovery = (Amount of purified compound / amount of original compound) x 100%

Here, amount of purified compound means the amount of substance formed after the recrystallization process. Amount of original compound means, the amount of impure substance taken to recrystallize.

Let’s consider an example to understand the calculation of percent yield.

Ex: If 14 g of copper was used in a recrystallization process and the amount of copper recovered at the end of the process is 12 g,

Percent recovery = (12 g/14 g) x 100% = 85.71 %

What is the Similarity Between Percent Yield and Percent Recovery?

• Both Percent Yield and Percent Recovery terms are percentages that are ratios multiplied by 100%.

What is the Difference Between Percent Yield and Percent Recovery?

Summary – Percent Yield vs Percent Recovery

Percent yield and percent recovery are two terms that are used to indicate the amount or the purity of the final product obtained from a chemical synthesis reaction. The difference between percent yield and percent recovery is that percent yield is calculated as a ratio between actual yield and theoretical yield whereas percent recovery is calculated as the ratio between the pure compound and initial compound.

Reference:

1.“How to Calculate Percent Recovery.” ScienceStruck. Available here 
2.Helmenstine, Anne Marie, D. “Percent Yield Definition and Formula.” ThoughtCo, Jan. 21, 2018. Available here 

Image Courtesy:

1.’Calcium carbonate rocks’By Ferdous – Own work, (CC BY-SA 3.0) via Commons Wikimedia  
2.’Cinnamic acid’By Aleksander Sobolewski via Wikimedia Commons, (CC BY-SA 4.0) via Commons Wikimedia