Chris Lloyd
Calibration of and Choosing Glassware
Objective
The objective of this lab is to illustrate how your choice of glassware can affect the precision and
accuracy of your result and data using statistical analysis.
Procedure
1.) Weigh a 150mL beaker (5 times)
2.) Use the 1, 2, and 5mL pipet’s to fill to the pipet mark and place in the 150mL beaker
3.) Repeat the delivery and weighing step (5 times for each pipet)
4.) Average the raw data and determine the standard deviation and relative standard
deviation
5.) Weigh a 10, 25, and 50mL volumetric flask
6.) Fill to the mark and re-weigh (5 times, each flask)
Data
Mass of 150mL Beaker
Trial
1
Mass(g)
72.5997
2
72.5997
3
72.5994
4
72.5993
Mass of 1mL of water in 150mL Beaker filled with 1mL pipet
Pipet 1
2
3
4
Trial 1
1.00098
1.00038
1.00028
0.99918
2
1.00078
1.00028
0.99938
0.99918
3
1.00068
1.00038
1.00028
0.99938
4
1.00058
0.99998
1.00038
0.99948
5
1.00048
0.99988
1.00048
0.99958
Average
1.0007
1.00018
1.00016
0.99936
Total Average
0.999884
Standard Deviation
0.000651
Relative Standard Deviation
0.0651%
Mass of 2mL of water in 150mL Beaker filled with 2mL pipet
Pipet 1
2
3
4
Trial 1
1.97778
1.97648
1.97618
1.97578
2
1.97768
1.92618
1.97608
1.97568
3
1.97748
1.97628
1.97598
1.97558
4
1.97698
1.97638
1.97598
1.97558
5
1.97678
1.97638
1.97588
1.97548
Average
1.97734
1.96634
1.97602
1.97562
Total Average
1.974132
Standard Deviation
0.010017
Relative Standard Deviation
0.507%
Mass of 5mL of water in 150mL Beaker filled with 5mL pipet
5
72.5993
5
0.99898
0.99888
0.99898
0.99908
0.99918
0.99902
5
1.97548
1.97538
1.97538
1.97528
1.97518
1.97534
Pipet 1
2
Trial 1
4.96998
4.96908
2
4.96968
4.96928
3
4.96948
4.96878
4
4.96888
4.96868
5
4.96918
4.96858
Average
4.96944
4.96888
Total Average
Standard Deviation
Relative Standard Deviation
Mass of empty 10mL volumetric flask
Trial
1
2
Mass(g)
12.9184
12.9184
3
4.96848
4.96838
4.96838
4.96838
4.96828
4.96838
3
12.9184
4
12.9185
Mass of 10mL of water measured in 10mL volumetric flask
Flask 1
2
3
Trial 1
10.0648
10.0639
10.0637
2
10.0843
10.0842
10.0841
3
10.0826
10.0824
10.0823
4
10.1172
10.1164
10.1158
5
10.0782
10.0781
10.078
Average
10.08542
10.085
10.08478
Total Average
Standard Deviation
Relative Standard Deviation
Mass of empty 25mL volumetric flask
Trial
1
2
Mass(g)
26.6401
26.6401
3
26.6401
4
26.6401
Mass of 25mL of water measured in 25mL volumetric flask
Flask 1
2
3
Trial 1
24.8641
24.8644
24.8612
2
24.8641
24.8643
24.8642
3
24.8641
24.8642
24.8642
4
24.8641
24.8642
24.8642
5
24.8643
24.8642
24.8642
Average
24.8641
24.8643
24.8636
Total Average
Standard Deviation
Relative Standard Deviation
Mass of empty 50mL volumetric flask
4
4.96828
4.96818
4.96808
4.96798
4.96778
4.96806
4.96005
0.042269
0.85%
5
12.9185
4
10.0637
10.0837
10.0821
10.0854
9.7506
10.0131
10.06933
0.068042
0.6757%
5
26.6401
4
24.8641
24.8643
24.8642
24.8642
24.8641
24.8642
24.8641
0.000601
0.0024%
5
4.96768
4.96768
4.96758
4.75719
4.96748
4.925522
Average
12.9184
5
10.0637
10.0836
10.082
10.08494
10.0776
10.07837
Average
26.6401
5
24.8641
24.8641
24.8641
24.8641
24.8641
24.8641
Trial
Mass(g)
1
38.1423
2
38.1423
3
38.1421
4
38.1422
Mass of 50mL of water measured in 50mL volumetric flask
Flask 1
2
3
Trial 1
49.49784
49.49794
49.49754
2
49.58444
49.58434
49.58394
3
49.47964
49.46784
49.46534
4
49.41534
49.41494
49.41474
5
49.50184
49.50154
49.50144
Average
49.49582
49.49332
49.49260
Total Average
Standard Deviation
Relative Standard Deviation
5
38.1424
4
49.49744
49.58374
49.46444
49.41454
49.50334
49.49270
49.4933
0.056206
0.1136%
Average
38.1423
5
49.49754
49.58374
49.46374
49.41414
49.50124
49.49208
Calculations
x +x +x +x +x
Average Weight = 1 2 53 4 5
Example49.49784+49.58444+49.47964+49.51534+49.50184
Average Weight=
=49.49582 grams
5
Standard Deviation
2
2
(x1 – xavg ) +(x2 – xavg ) +…+(xn – xavg )
=√
n-1
Example-
2
(49.49582-49.4933)2 +(49.49332-49.4933)2 +(49.49260-49.4933)2 +(49.49270 − 49.4933)2 +(49.49208-49.4933)2
4
= 0.056206
√
Relative Standard Deviation=
Standard Deviation
×100
Average Weight
Example0.056206
×100=.0.1136%
49.4933
Conclusion
Upon completion of the analysis our results suggest that the 1mL pipet and the 25mL volumetric
flask had the smallest standard deviation values. As the pipets and volumetric flasks increase in
volume, the standard deviation should decrease however our results didn’t prove that therefore
there was most likely in error on our part by not being careful when measuring.
After Laboratory Questions
1.) It would be best to use 49mL of solution because the 50mL buret is more accurate with a
large amount of solution. However the 56mL wouldn’t be best because you would have
to refill the buret because it can only hold 50mL.
2.) Vbase x Mbase = Vacid x Macid
(0.04356L)x(0.1012M) = (0.050L)xMacid
Macid=0.0889M
%Error=√(
.89×100 2
.0025×100 2
.05×100 2
) +(
) +(
) =3.21%
43.56
.1012
50