Zach Bensley
September 5, 2012
Experiment One
Calibration of and Choosing Glassware
Introduction:
The principle of this lab is to demonstrate the different techniques in using a variety of
different pieces of the volumetric glassware. This lab will not only allow students to use different
pieces of glassware, but will also demonstrate how precision and accuracy will be affected the choice
of volumetric glassware.
Procedure:
Calibration of Pipettes:
A clean 200 mL beaker was massed five times to determine the empty weight. 1, 2
and 5 mL pipette were used and the pipettes were filled with water up to the mark. Then the
volume was delivered to the beaker. This transaction was repeated five more times. The
average raw data for each pipette was determined and the standard deviation and relative
deviation was calculated.
Calibration of Volumetric Glassware:
10, 25 and 50 mL volumetric flasks were massed. The volumetric flasks were filled
up to mark with water and re-weighed. This transaction was repeated five more times for
every volumetric flask.
Data:
Calibration of Pipettes:
Mass of 200 mL Beaker:
Trials
1
2
3
4
5
Average Mass
Mass (g)
80.0442
80.0417
80.0415
80.0418
80.0400
80.0418
1 mL Pipette
Trial
1
2
3
4
5
Average Mass
Mass of Water and 200 mL
Beaker (g)
81.0355
81.0209
81.0331
81.0307
81.0296
81.0299
Mass of Water (g)
Mass of Water and 200 mL
Beaker (g)
Mass of Water (g)
0.99376
0.97906
0.99126
0.98886
0.98776
0.98812
2 mL Pipette
Trial
1
2
3
4
5
Average Mass
81.9957
81.9596
81.9949
81.9846
81.4964
81.9862
1.95386
1.91776
1.95306
1.94276
1.95456
1.94440
Mass of Water and 200 mL
Beaker (g)
85.0125
85.0127
85.0047
84.9877
84.9952
85.0026
Mass of Water (g)
5 mL Pipette
Trial
1
2
3
4
5
Average Mass
4.97066
4.97086
4.96286
4.94586
4.95336
4.96072
Calibration of Volumetric Flasks:
Mass of 10 mL Volumetric Flask
Trial
1
2
3
4
5
Average
Mass of 10 mL Volumetric Flask with Water
Trial
Mass of Volumetric Flask with
Water (g)
1
19.3053
2
19.3048
3
19.3037
4
19.3037
5
19.3041
Average
19.3043
Mass of 25 mL Volumetric Flask
Trial
1
2
3
4
5
Average
Mass of 25 mL Volumetric Flask with Water
Trial
Mass of Volumetric Flask with
Water (g)
1
45.0807
2
45.0806
3
45.0804
Mass (g)
9.3546
9.3544
9.3542
9.3546
9.3545
9.3545
Mass of Water (g)
9.95084
9.95034
9.94924
9.94924
9.94964
9.94986
Mass (g)
20.1689
20.1684
20.1681
20.1686
20.1683
20.1685
Mass of Water (g)
24.91224
24.91214
24.91194
4
5
Average
45.0799
45.0800
45.0803
24.91144
24.91154
24.91186
Mass of 50 mL Volumetric Flask
Trial
1
2
3
4
5
Average
Mass (g)
35.8745
35.8744
35.8740
35.8727
35.8737
35.8739
Mass of 50 mL Volumetric Flask with Water
Trial
Mass of Volumetric Flask with
Water (g)
1
86.6069
2
86.6052
3
86.6044
4
86.6039
5
86.6041
Average
86.6049
Mass of Water (g)
50.73304
50.73134
50.73054
50.73004
50.73024
50.73104
Calculated Data:
1 mL Pipette
2 mL Pipette
5 mL Pipette
10 mL Volumetric
Flask
25 mL Volumetric
Flask
50 mL Volumetric
Flask
Calculations:
Average Mass
X

x
n
X= average of data
x= data points
n= number of data
points

Mass of Water
Average Mass of Water
(g)
0.98812
1.9444
4.96072
9.94986
Standard Deviation
0.0055664
0.0156532
0.01096804
0.000785196
Relative Standard
Deviation
0.564447
0.805041
0.221097
0.0071209
24.91186
0.000356371
.00143053
50.73104
0.00108046
.0021978
Example of Average Mass
Average mass for 200 mL Beaker:
80.0442  80.0417  80.0415  80.0418  80.0400

5
= 80.0418 g
Example of Mass of Water
Xwater= A-B
Xwater= Mass (g) of
water in
beaker/volumetric
flask
A= Mass of water and
beaker/volumetric
flask
B= Average mass of
beaker/volumetric
flask without water
Calculation using 200 mL Beaker with 1 mL pipette:
Standard Deviation
Example of Standard Deviation
Standard deviation calculation for 200 mL beaker with 2 mL pipette of water:
Sd 

 (x  X )
n 1
2
d

(1.95386 1.94440) 2  (1.91776 1.94440) 2  (1.95306 1.94440) 2  (1.94276 1.94440) 2  (1.95456 1.94440) 2
5 1
Sd= Standard

deviation
x= Data point
X= Average
n= Number of data
points
Sd= 0.0156532
Relative Standard
Deviation
Example of a Relative Standard Deviation
RSD  100 *

Xwater= 81.0229 g – 80.0418 g = 0.9881 g
Sd
X
RSD= Relative
standard deviation
Sd= Standard
deviation 
X= average
Calculation for 200 mL beaker with 2 mL pipette:
RSD  100 *
0.0156532
1.94440
RSD= 0.0805041
Conclusion:
During this experiment, there were numerous sources of error that needs to be accounted
for. An example of a source of error is the massing of the individual beakers and volumetric flasks.
Sometimes, when the beaker or volumetric flask was on the balance pan, there were fluctuations in
the mass. Hence, there was no distinct or accurate mass. Another source of error in this experiment
involved with the pipette. The reason why the pipette was not successful in comparison to the
volumetric flasks (compared both of the standard deviations to one another) is because when
transferring the water from the pipette to the beaker, some of the water may have not fully
transferred or spilled out from the beaker.
A change in the procedure would include for every time the water and the volumetric
flask/beaker were massed, make sure to dry the volumetric flask/beaker for every new trial. That
way, there won’t be any error in the massing of the volumetric flask/beaker. Another change will be
involving the pipette. Before transferring the pipette over to the beaker, first decant the water from
the pipette into a graduated cylinder. That way, one will see how much more or less water is needed
to put into the beaker.
Overall, according to the data, the volumetric flasks were more precise than the pipettes.
The reason why the volumetric flasks were more precise is because the standard deviation was
significantly smaller than the pipette’s standard deviation. For example, for 1 mL pipette, the
standard deviation was 0.0055664, while the 10 mL volumetric flask’s standard deviations was
0.000785196.