Monique A. Gray
Experiment 1
Quantitative Analysis
Experiment 1: Calibration Of and Choosing Glassware
Introduction
The fundamental goal of this experiment is to explore and understand the various techniques used for
measuring solutions with various types of volumetric glassware. Also, to understand the significance of precision
and accuracy, and how these concepts are affected by the types and choices of glassware used to measure specific
volumes of solutions. In order to calculate the value of uncertainty, the standard deviation and relative standard
deviation will be calculated and evaluated closely.
Experimental Procedure
Calibration of Pipets
-
-
-
-
Weight a clean dry 50mL beaker five times and records each measurement precisely.
Using the 1mL pipet, fill with water to the designated line and dispense water into the 50mL beaker and
weight five times. Record each measurement precisely. Repeat four more trials of this procedure for the
1mL pipet. (Make sure beaker is dried between each trial)
Using the 2mL pipet, fill with water to the designated line and dispense water into the 50mL beaker and
weight five times. Record each measurement precisely. Repeat four more trials of this procedure for the
2mL pipet. (Make sure beaker is dried between each trial)
Using the 5mL pipet, fill with water to the designated line and dispense into the 50mL beaker and weight
five times. Record each measurement precisely. Repeat four more trials of this procedure for the 5mL
pipet. (Make sure beaker is dried between each trial)
Take the average of each individual trial for each pipet used. Then take the total average of all the
individual averages.
Calculate the standard deviation and the relative standard deviation.
Calibration of Volumetric Glassware
-
Weight a clean, dry 10mL volumetric flask five times. Record each measurement precisely.
Weight a clean, dry 25mL volumetric flask five times. Record each measurement precisely.
Weight a clean, dry 50mL volumetric flask five times. Record each measurement precisely.
Fill a 10mL volumetric flask to the designated mark and weight the flask five times. Record each
measurement precisely. Repeat four more trials of this procedure for the 10mL volumetric flask.
Fill a 25mL volumetric flask to the designated mark and weight the flask five times. Record each
measurement precisely. Repeat four more trials of this procedure for the 25mL volumetric flask.
Fill a 50mL volumetric flask to the designated mark and weight the flask five times. Record each
measurement precisely. Repeat four more trials of this procedure for the 50mL volumetric flask.
Take the average of each individual trial for each pipet used. Then take the total average of all the
individual averages.
Calculate the standard deviation and the relative standard deviation.
Monique A. Gray
Experiment 1
Data
Table 1. Dry weight of Volumetric Glassware in grams (g).
50mL Beaker
32.0477g
32.0482g
32.0479g
32.0480g
32.0480g
Dry Weights Of Volumetric Glassware
10mL Volumetric
25mL Volumetric
Flask
Flask
8.986g
18.523g
8.987g
18.521g
8.987g
18.523g
8.986g
18.524g
8.986g
18.523g
50mL Volumetric
Flask
35.966g
35.967g
35.966g
35.966g
35.965g
Table 2. Wet weights of the 1mL Pipet in grams (g).
Trial 1
33.082g
33.083g
33.082g
33.081g
33.082g
Trial 2
33.113g
33.114g
33.112g
33.113g
33.111g
Wet Weights of 1mL Pipet
Trial 3
33.107g
33.106g
33.106g
33.105g
33.107g
Trial 4
33.070g
33.068g
33.068g
33.067g
33.067g
Trial 5
33.074g
33.074g
33.073g
33.073g
33.072g
Trial 4
34.135g
34.134g
34.135g
34.134g
34.134g
Trial 5
34.084g
34.083g
34.084g
34.083g
34.085g
Table 3. Wet weights of the 2mL Pipet in grams (g).
Trial 1
34.079g
34.080g
34.079g
34.078g
34.078g
Trial 2
34.106g
34.107g
34.106g
34.105g
34.105g
Wet Weights of 2mL Pipet
Trial 3
34.074g
34.072g
34.073g
34.074g
34.073g
Table 4. Wet weights of the 5mL pipet in grams (g).
Wet Weight of the 5mL Pipet
Trial 1
36.972g
36.971g
36.972g
36.973g
36.972g
Trial 2
37.014g
37.013g
37.014g
37.013g
37.013g
Trial 3
36.944g
36.944g
36.945g
36.943g
36.943g
Trial 4
36.996g
36.995g
36.996g
36.997g
36.997g
Trial 5
36.959g
36.958g
36.959g
36.960g
36.958g
Monique A. Gray
Experiment 1
Table 5. Wet weights of the 50mL volumetric flask in grams (g).
Wet Weight of the 50mL Volumetric Flask
Trial 1
85.745g
85.743g
85.746g
85.743g
85.742g
Trial 2
85.753g
85.754g
85.756g
85.755g
85.755g
Trial 3
85.766g
85.764g
85.763g
85.764g
85.765g
Trial 4
85.794g
85.794g
85.794g
85.795g
85.793g
Trial 5
85.801g
85.800g
85.799g
85.799g
85.799g
Table 6. Wet weights of the 25mL volumetric flask in grams (g).
Trial 1
43.350g
43.351g
43.351g
43.350g
43.349g
Wet Weights of the 25mL Volumetric Flask
Trial 2
Trial 3
43.293g
43.368g
43.294g
43.368g
43.293g
43.368g
43.292g
43.367g
43.294g
43.367g
Trial 4
43.343g
43.340g
43.341g
43.340g
43.339g
Trial 5
43.355g
43.354g
43.354g
43.353g
43.353g
Table 7. Wet weights of the 10mL volumetric flasks.
Wet Weights of the 10mL Volumetric Flask
Trial 2
Trial 3
Trial 4
18.918g
18.901g
18.897g
18.916g
18.901g
18.897g
18.919g
18.899g
18.896g
18.918g
18.899g
18.899g
18.917g
18.900g
18.896g
Trial 1
18.922g
18.922g
18.923g
18.923g
18.922g
Trial 5
18.818g
18.817g
18.818g
18.818g
18.817g
Calculations
To calculate the average weight of a trial. You add all the data points collected in the specific trial and then divide
that total number by the number of of data points there are.
Mean Calculation
:
𝑥1 + 𝑥2 + 𝑥3 + 𝑥4 + 𝑥5
𝑛
Example: Mean Calculation (Using the data for trial 1 of the 10mL pipet)
18.922𝑔 + 18.922𝑔 + 18.923𝑔 + 18.923𝑔 + 18.922𝑔
5
= 18.9224g
Monique A. Gray
Experiment 1
Standard Deviation Formula
√𝑥1 − 𝑎𝑣𝑔)2 + (𝑥2 − 𝑎𝑣𝑔)2 + (𝑥3 − 𝑎𝑣𝑔)2 + (𝑥4 − 𝑎𝑣𝑔)2 + (𝑥5 − 𝑎𝑣𝑔)2
𝑛−1
Relative Standard Deviation Formula
𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛
𝑥 100
𝑡𝑜𝑡𝑎𝑙 𝑎𝑣𝑒𝑟𝑎𝑔𝑒
Example: Standard Deviation Calculation- (Using data for wet weight of 1mL Pipet)
√33.0820𝑔 − 33.0886𝑔)2 + (33.1126𝑔 − 33.0886𝑔)2 + (33.1062𝑔 − 33.0886𝑔)2 + (33.0732𝑔 − 33.0886𝑔)2 + (33.0690𝑔 − 33.0886𝑔)2
5−1
= 0.009844542
Example: Relative Standard Deviation Calculation- (Using data for wet weights of 1mL pipet)
0.009844542
𝑥 100
33.0886
= 0.029752066 %
Averages, Standard Deviation, and Relative Standard Deviation of the Wet Weights of the
1mL Pipet
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
33.0820g
33.1126g
33.1062g
33.0732g
33.0690g
Total Average
33.0886
Standard Deviation
0.009844542
Relative Standard
Deviation
0.029752%
Averages, Standard Deviation, and Relative Standard Deviation of the Wet Weights of the
2mL Pipet
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
34.077g
34.1058g
34.0732g
34.1344g
34.0838g
Total Average
34.09484
Standard Deviation
0.012731737
Relative Standard
Deviation
0.0373421%
Monique A. Gray
Experiment 1
Averages, Standard Deviation, and Relative Standard Deviations of the Wet Weights of the
5mL Pipet
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
36.972g
37.0134g
36.9438g
36.9962g
36.9588g
Total Average
36.97684
Standard
0.000787989
Deviation
Relative Standard
Deviation
0.002131%
Averages, Standard Deviation, and Relative Standard Deviation of the Wet Weights of the
10mL Volumetric Flask
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
18.9224g
18.9176g
18.9000g
18.8970g
18.8176g
Total Average
18.89092
Standard
Deviation
0.021213857
Relative Standard
Deviation
0.1122966%
Averages, Standard Deviation, and Relative Standard Deviation of the Wet Weights of the
25mL Volumetric Flasks
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
43.3502g
43.2932g
43.3676g
43.3406g
43.3538g
Total Average
43.34108
Standard
Deviation
Relative Standard
Deviation
0.014232459
0.0328383%
Averages, Standard Deviation, and Relative Standard Deviations of the Wet Weights of the
50mL Volumetric Flask
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
85.7438g
85.7546g
85.7644g
85.794g
85.7996g
Total Average
85.77128
Standard
Deviation
0.024489416
Relative Standard
Deviation
0.028552%
Monique A. Gray
Experiment 1
Conclusion
The overall objective of this experiment was to understand the how accuracy and precision are greatly affected by
the types of volumetric glassware we use. Also, how accurately we dispense solution into a particular volumetric
glassware affect precision and accuracy. Using the SD (standard deviation) and RSD (relative standard deviation,
my team was able to visually see and understand the error in our measurement and how even though we thought
we were dispensing the correct amount of solution into the glassware, we still had a sufficient amount of
uncertainly and error associated with our measurements.
Thus, a lot of factor could have contributed to the error we obtained. For example, we could have not been
accuracy feeling the glassware or precisely reading the measurements. Also, if the glassware isn’t property dried
between each trial it could cause minor/major error depending on the volume of the glassware. Even not properly
using the scale could cause major error. Another factor that could cause error is not properly performing the
calculations. Minor errors in calculation could potentially lead to major error associated with the experiment.
I have noticed that the smaller the glassware the harder it is to read. Thus, my calculation illustrated that smaller
glassware is associated with greater error. My calculated error for my volumetric glassware was 0.1122966% for
the 10mL volumetric flask, 0.0328383% for the 25mL volumetric flask, and 0.028552% for the 50mL flask. As you
can see the error decreased as the volume of the glassware grew. Therefore, when weighting and measurement
solution it is always better to use the bigger glassware and glassware that is appropriate for that particular
measurement.
Post-Lab Questions
When referring to measuring 20mL, 49mL, 56mL of solution with a 50mL buret, it is best to measure 49mL with a
50mL buret because for that volume of solution it would just be the appropriate amount to measure and also it
will accumulate less error when you’re reading and measuring the solution. For the 20mL of solution, if you were
to measure out that amount using a 50mL buret you would obtain a great amount for error because there would
be a great amount for of uncertainly when trying to accurately for the 20mL mark. The best thing to do would be
to measure out 20mL of solution with as big of a buret as possible but also with the most appropriate volume as
possible. For example maybe using a 20mL buret on 30mL buret would work. For measuring out the 56mL, it
wouldn’t be the best idea to measure it with a 50mL buret because a 50mL buret can only hold 50mL of solution
and then you would have to measure out 6mL using a 50mL buret and that would produce a huge amount of error.
We are given:
Volume of base is 43.56mL, SD of 0.89mL
Molarity of Base is 0.1012M, SD of 0.0025
Volume of Acid is 50mL, SD of 0.05mL.
𝑉1 𝑀1 = 𝑉2 𝑀2
(43.56mL) (0.1012M) = (50mL) (x)
x = 0.08816544M
.89×100 2 .0025×100 2 .05×100 2
Percent Error=√(
) +(
) +(
) =3.206243908%
43.56
.1012
50
Monique A. Gray
Experiment 1