Percent error is a useful tool in chemistry for determining the accuracy of experimental data by comparing results to theoretical predictions or accepted values. This measurement provides insight into potential discrepancies and can help to improve accuracy in future experiments. In this article, we will explore how to calculate the percent error in chemistry.

Definition of Percent Error

In chemistry, percent error is the difference between an experimental value and a known or accepted value, expressed as a percentage. Mathematically, percent error is calculated using the following formula:

Percent Error = (|Experimental Value – Accepted Value| / Accepted Value) × 100%

Calculating Percent Error: A Step-by-Step Guide

To calculate percent error in chemistry, follow these steps:

1. Identify Experimental and Accepted Values: Determine the experimental value (the result obtained from the experiment) and the accepted value (a trusted, known value for comparison).

2. Calculate the Difference: Subtract the accepted value from the experimental value. Regardless of whether this value is positive or negative, use the absolute value (the positive value) when calculating percent error.

3. Divide by the Accepted Value: Divide the absolute difference obtained in step 2 by the accepted value.

4. Multiply by 100%: To express the result as a percentage, multiply the result from step 3 by 100%.

5. Report Your Percent Error: The final result is the percent error between your experimental value and accepted value.

Example of Calculating Percent Error in Chemistry

Suppose you conducted an experiment to determine the concentration of a salt solution and obtained a result of 1.10 M (molarity). The known or accepted concentration is 1.00 M.

1. Identify Experimental and Accepted Values:

Experimental Value = 1.10 M

Accepted Value = 1.00 M

2. Calculate the Difference:

|1.10 M – 1.00 M| = 0.10 M

3. Divide by the Accepted Value:

0.10 M / 1.00 M = 0.10

4. Multiply by 100%:

0.10 × 100% = 10%

5. Report Your Percent Error:

The percent error in this experiment is 10%.

Conclusion

Calculating percent error provides valuable insights into experimental accuracy and potential sources of error in your work as a chemist. By routinely analyzing data for discrepancies, you can refine experimental procedures, improve precision, and work towards more accurate results in your experiments. Remember to use the percent error formula and follow the step-by-step guide outlined above to measure the accuracy of your chemistry data effectively.