1. Calculating Percent Error

2. What is it??
Percent Error is used to determine the inaccuracy, in percentage, of a estimated value, compared to the actual value.

3. The Components of the Formula
Estimated Value (Measured Value)- The educated guess of an experiment.
Actual Value (What you should have gotten!)- This value is the exact value.

4. The formula X 100 = Percent Error
The Formula for Percent Error is a follows:
(The Difference)
Actual Value
Remember:
PS. We multiply by 100 to make to make the decimal a percent.
X 100 = Percent Error

5. Practice Problems
1.) Johnny calculates from an experiment that he has 22.7 grams of carbon. However, he should have gotten 21.8 grams of carbon, which was the actual value for this experiment. What was his percent error?
Remember: (Difference) X 100 = PE
Actual Value

6. Answer (Difference) X 100 = PE AV (22.7 - 21.8) X 100 = PE 21.8

7. More Practice
2.) The actual value for the absorption of carbon is Steven calculated that absorption was What is the percent error in Steven’s experiment?

8. Answer (Difference) X 100 = PE AV (.235 - .135) X 100 =PE .135

9. Additional practice
3.) The boiling point of water is 100°C. During an experiment, water came to a boil at 97°C according to the thermometer that was being used. What is the percent error of the thermometer?
answer 3.0%

10. Additional practice
4.) An experiment was conducted to find the mass of one mole of carbon atoms. The results of the experiment showed that a mole of carbon atoms had a mass of g. The actual value of a mole of carbon atoms is grams. What is the percent error in this experiment?
answer 1.4%

11. Additional practice
5.) An experiment performed to determine the density of lead yields a value of g. The actual value for the density of lead is g. Find the percent error.
answer 3.4%