# AP Chemistry : Yield and Error

## Example Questions

### Example Question #33 : Laboratory Techniques And Analysis

3 mols of  are placed in a reactor and react to form  as in the above reaction. At equilibrium, there are 1.75 mols of .

What is the percent conversion of ?

Explanation:

To find the percent conversion, use the following equation:

Initially there are 3 mols of . We know that every 1 mol of  that is consumed in the reaction yields 1 mol of . Therefore, the final amount of  in mols is

Plugging this into the above equation gives a conversion rate of 58%.

### Example Question #1 : Yield And Error

You run an experiment in order to empirically find the gas constant, .  You find

You know from the literature that

What is the percent error in your experimental value of ?

Explanation:

To find the percent error in your  value, you can use the following equation:

Doing this, we find the percent error to be 4.6%.

### Example Question #1 : Yield And Error

Suppose that a chemist working in a lab is trying to synthesize caffeine. In doing so, he predicts that he can produce  of caffeine. After the chemist finishes synthesizing the caffeine, he weighs it only to find out that  are produced. What is the percent yield of caffeine in this synthesis process?