Accuracy and Precision
Accuracy:_____________________________________________________________
______________________________________________________________________
In lab, the accuracy of a given measurement will be limited by ___________________
________________________and __________________________________________
Precision:_____________________________________________________________
______________________________________________________________________
Practice: The density of a given substance is 2.1 g/ml. Three students measured the
density of the object in lab and there results are shown in the table below. Discuss
each student’s data with respect to accuracy and precision.
Trial
1
2
3
4
Student A
2.0
2.9
1.7
3.1
Student B
2.2
2.2
2.1
2.0
Student C
3.4
3.5
3.4
3.4
Student A_______________________________________________________
Student B________________________________________________________
Student C_________________________________________________________
Accuracy, Precision, and Percent Error
Chemistry
Percent Error
Percent error =
Percent error will always be a ______________number.
Practice:
1. The boiling point of water is 100oC. During an experiment, water came to a boil at
97oC according to the thermometer that was being used. What is the percent
error of the thermometer?
2. An experiment was performed to determine the density of water. The results of
the experiment showed that water had a density of 1.15 g/mL. What was the
percent error in this experiment?
3. 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
15.78 g. The accepted value of a mole of carbon atoms is 16.00 grams. What is
the percent error in this experiment?
4. An experiment performed to determine the density of lead yields a value of
10.95 g/cm3. The accepted value for the density of lead is 11.342 g/cm 3. Find the
percent error.
5. Find the percent error in a measurement of the boiling point of bromine if the
laboratory figure is 40.6oC and the accepted value is 59.35oC.
1. 3%
2. 15%
3. 1.375%
4.
3.456%
5. 31.6%