Chapter 12, Problem 70A

Interpretation Introduction

Interpretation : The percent yield is to be calculated. The percent yield greater than 100 percent is to be evaluated.

Concept Introduction : The effectiveness of a laboratory-based reaction is measured by the percent yield. The highest amount of product that could be produced from specific amounts of reactants is known as the theoretical yield. The term "actual yield" refers to the volume of product that forms during a reaction in a lab.

The formula to calculate the percentage yield is given as:

  $\text{Percent}\text{yield =}\frac{\text{actual}\text{yield}}{\text{theoretical}\text{yield}}\times 100\%$   ...... (1)

Answer to Problem 70A

The percent yield is $115\%$ .

Explanation of Solution

The particular reaction could produce $\text{55}\text{g}$ of a product which is the theoretical yield.

The amount of product produced by performing the reaction is $63\text{g}$ which is the actual yield.

The formula to calculate the percentage yield is given as:

  $\text{Percent}\text{yield =}\frac{\text{actual}\text{yield}}{\text{theoretical}\text{yield}}\times 100\%$   ...... (1)

To calculate the percent yield, substitute the values in equation (1).

  $\begin{array}{c}\text{Percent}\text{yield =}\frac{\text{actual}\text{yield}}{\text{theoretical}\text{yield}}\times 100\%\\ =\frac{63\text{g}}{55\text{g}}\times 100\%\\ =115\%\end{array}$

The percent yield is $115\%$ .

The percent yield greater than 100 is due to inaccuracy.

The presence of impurities in the measured product of the reaction that results in a greater mass of this product (for which product purification is desirable); the occurrence of the secondary reaction that also results in the formation of an undesirable product that increases the mass of the main product; and inaccurate measurements made in the laboratory are some factors that can cause a percent yield to be greater than 100%.