Standard Deviation
BASIC INFORMATION

  • The following data represents acid/base titrations completed by two (2) different groups. A standardized acid was used to determine the strength of a base.
  • Determine, by means of frequency diagrams and the standard deviation for the population for each group, which group is more precise. A link that may help: Statistics Every Writer Should Know.
  • For each set of data, compute the mean, the standard deviation for the population, and complete a frequency diagram using a bar graph interval of 0.3 mL (start with 20.0 ml). For the diagrams, mark off and label the mean for each graph. Some links that may help with the Calculation of Mean, SD, and the construction of Histograms: Site 1 (SDn and Graph), Site 2a(SDn-1), Site 2b (Graph).
THE DATA

GROUP 1
Titrant Readings
in mL

21.5 20.5 23.5
22.5 22.4 22.6
22.2 22.0 21.9

22.8 22.8 22.6
21.8 22.6 22.0
21.5 21.6 22.0

21.5 21.6 22.0
22.3 22.0 22.9
21.7 23.0 22.6

21.7 23.0 22.6
21.5 22.0 22.0
22.2 22.0 21.9

GROUP 2
Titrant Readings
in mL

21.5 22.0 22.0
21.8 22.6 22.0
21.5 20.5 23.5

22.5 23.5 22.6
23.3 23.9 20.2
23.8 23.9 20.2

23.6 23.6 25.1
23.3 23.0 22.8
23.4 23.5 23.2

21.9 20.2 20.0
22.1 22.5 22.0
23.3 23.0 22.0

THE LABORATORY REPORT