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A 25 mL class A pipet and an Ohaus Explorer model EX124 analytical balance are used to obtain the following experimental data:Trial 1 (g)Trial 2 (g)Trial 3 (g)Trial 4 (g)Trial 5 (g)Mass Beaker54.600354.599654.600354.598754.5995Mass w solution80.218080.114180.018780.650480.7774Solution NumberMass NaCl (g)Volumetric Flask (mL)Pipet (mL)Mass BeakerMass Beaker w solution11.05471002568.4012156993.5627530521.98651002568.4006758193.740100333.00581002568.4011903993.9284989444.09871002568.4002353294.1344957354.99841002568.401387494.298831566.02451002568.4009346294.50244286
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Chemistry 366 Homework Problem Set
Widener University
Dr. Van Bramer
January 2019
Propagation of Error and Statistics Worksheet
A 25 mL class A pipet and an Ohaus Explorer model EX124 analytical balance are used to obtain the
following experimental data:
Mass Beaker
Mass w
solution
1.
2.
3.
4.
5.
6.
Trial 1 (g)
54.6003
80.2180
Trial 2 (g)
54.5996
80.1141
Trial 3 (g)
54.6003
80.0187
Trial 4 (g)
54.5987
80.6504
Trial 5 (g)
54.5995
80.7774
Calculate the density of the solution for each trial
Use propagation of error to determine the uncertainty in the density of the solution for each trial.
Determine the average density for the solution.
Determine the standard deviation for the density of the solution.
Determine the 90% confidence interval for the density of the solution.
Determine the 95% confidence interval for the density of the solution.
A set of salt water standards is created by weighing sodium chloride, adding to a 100 mL class A volumetric
flask and diluting to the mark. 25 mL of this solution is transferred into a beaker with a class A volumetric
pipet.
Solution
Number
1
2
3
4
5
6
1.
2.
3.
4.
Mass NaCl (g)
1.0547
1.9865
3.0058
4.0987
4.9984
6.0245
(mL)
100
100
100
100
100
100
Pipet (mL)
Mass Beaker
25
25
25
25
25
25
68.40121569
68.40067581
68.40119039
68.40023532
68.4013874
68.40093462
Mass Beaker w
solution
93.56275305
93.7401003
93.92849894
94.13449573
94.2988315
94.50244286
Create a calibration curve using the density and salinity (ppt) of the standards.
Use this calibration curve to determine the salinity of the unknown solution for each trial
Determine the average salinity for the solution
Determine the uncertainty in the salinity of the solution based on the uncertainty in the calibration
curve.
5. Determine the standard deviation for the salinity of the solution
6. Determine the 90% confidence interval for the salinity of the solution
7. Determine the 95% confidence interval for the salinity of the solution
trial 1
trial 2
trial 3
trial 4
trial 5
average
mass beaker mass w solution solution mass
54.6003
80.2180
25.6177
54.5996
80.1141
25.5145
54.6003
80.0187
25.4184
54.5987
80.6504
26.0517
54.5995
80.7774
26.1779
54.5997
80.3557
25.7560
std. dev.
90% interval
95% interval
0.3380
density
1.0247
1.0206
1.0167
1.0421
1.0471
1.0302
volume
25.0000
25.0000
25.0000
25.0000
25.0000
25.0000
% uncertainty
80.9000
80.8000
80.7000
mass with solution (g)
uncertainty
80.6000
80.5000
80.4000
80.3000
80.2000
80.1000
80.0000
79.9000
54.5986
54.5988
54.5990
54.5992
54.5994
mass beaker (g)
y = -361.82x + 19836
54.5994
54.5996
mass beaker (g)
54.5998
54.6000
54.6002
54.6004
solution no. NaCl (g)
pipet (ml)
mass beaker beaker w solution
1
1.0547
100
25 68.4012157
93.5627531
2
1.9865
100
25 68.4006758
93.7401003
3
3.0058
100
25 68.4011904
93.9284989
4
4.0987
100
25 68.4002353
94.1344957
5
4.9984
100
25 68.4013874
94.2988315
6
6.0245
100
25 68.4009346
94.5024429