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Hi, I am looking for someone to write an article on calibration of glassware Paper must be at least 500 words. Please, no plagiarized work!
Hi, I am looking for someone to write an article on calibration of glassware Paper must be at least 500 words. Please, no plagiarized work! This exercise deals with calibration of two volumetric glassware that are used in analytical chemistry. burette and canonical flask. These tools are extensively used in analysis in the laboratory. Calibration was carried out by getting the mass of required apparatus and liquid. First of all, weigh the empty canonical flask. Then fill the pipette/burette with water till the water reaches the mark on the burette/pipette. Thereafter, transfer the measured water into the canonical flask. Now weigh the canonical flask when it is filled with water. Repeat the same procedure three times for reproducibility. Get rid of all the water in the canonical flask. All the other volumes of water marks in canonical flask will be measured by the balances that read to ±0.0001 g for this experiment. The only exception will be the calibration of 100 mL volumetric flask mark. For that mark, one should use the balances that read to ±0.001 g because they can handle heavier weights. The estimated uncertainties are weight of water, error in sighting the level of the water, density of water and error in temperature reading. So as to avoid introducing random and systematic errors in measurements, it is essential to calibrate them.
Introduction
The main goal of this exercise is to calibrate these volumetric glass wares:
• 50 mL burette
•10 mL pipette
•25 mL pipette
•50 mL volumetric flask
•100 mL volumetric flask
Obtained from: http://en.wikipedia.org/wiki/File:Brand_volumetric_flask_100ml.jpg
Volumetric glassware is manufactured to specific standards, but it is not all identical and the manufacturing tolerances are not as strict as you may require for certain Lab measurements. Indeed, small variations often occur from one piece of glassware to the next. It is possible to correct for systematic errors in the calibration markings, and such corrections are necessary for the most accurate analytical work.
Experimental Section
Recalibration is carried out by weighing the quantity of water contained in the volumetric container. The mass of the liquid is converted to required volume using density of water:
Volume = mass/density
Volumetric measurements are affected by two main systematic errors. parallax and temperature. The volume that a certain liquid occupies varies with temperature. Even the volume of the apparatus holding the liquid is also affected by the temperature. 21 degrees Celsius has been taken as normal room temperature for calibration.
At times values of volume are corrected using the formula below
V20 = V [1 + 0.000025 (20 - t)]
Another source of systematic error when using volumetric apparatus is parallax. A correction to this error to this should be applied during procedures of calibration as indicated below.
Adapted from Quantitative Analysis, 4th Ed. by Conway Pierce,
Edward L. Haenisch and Donald T. Sawyer. John Wiley &. Sons. 1948.
The correct readings are ensured by positioning the eye as the middle reading level above.
Results and Discussion
The significant data was obtained and included in the table and graph.
Table 1 provides an example of the data used to calibrate Burette.
Burette Calibration
 .
 .
 .
 .
 .
Density of water (at 21 degrees C in gm/L):
1.0030
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
Volume delivered (mL)
10
20
30
40
50
Empty Wt. (g)
29.2307
29.2307
29.2307
29.2307
29.2307
Trial 1, water + glassware (g)
42.5793
52.3429
62.1361
72.2320
82.1303
Trial 2, water + glassware (g)
42.6630
52.3588
62.0675
72.2007
81.2264
Trial 3, water + glassware (g)
42.5030
52.3524
62.0917
72.2505
81.9815
Trial 1, density corrected (mL)
13.3087
23.0431
32.8070
42.8727
52.7414
Trial 2, density corrected (mL)
13.3921
23.0589
32.7386
42.8415
51.8402
Trial 3, density corrected (mL)
13.2326
23.0525
32.7627
42.8911
52.5930
Mean (mL)
13.3111
23.0515
32.7694
42.8684
52.3915
Stdev (mL)
0.0798
0.0080
0.0347
0.0251
0.4832
%RSD
0.5994
0.0346
0.1059
0.0585
0.9223
Error (mL)
3.3111
3.0515
2.7694
2.8684
2.3915
Rounded Error (mL)
3
3
3
3
2
The table also shows calculated mean and standard deviation.
This table contains as many as 50 trials in order to get more reliable estimation of the measurement uncertainties. The data value was arrived at by conducting a minimum of three trials to obtain a suitable calibration. All the findings were recorded in the format above.
Table 2 indicates data used in calibrating volumetric glassware
Volumetric Glassware Calibration
 .
 .
 .
 .
 .
 .
Density of water (at 21 degrees C in gm/L):
 .
 .
 .
1.0030
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
10mL pipette
25mL pipette
50mL flask
100mL flask
Empty Wt.(g)
 .
 .
29.2307
29.2307
36.4715
64.07
Trial 1, water + glassware (g)
 .
 .
39.1278
54.1623
86.0322
163.41
Trial 2, water + glassware (g)
 .
 .
37.5909
54.1406
86.0661
163.47
Trial 3, water + glassware (g)
 .
 .
39.8412
54.2983
86.0890
163.41
Trial 1, density corrected (mL)
 .
 .
9.8675
24.8570
49.4125
99.04
Trial 2, density corrected (mL)
 .
 .
8.3352
24.8354
49.4463
99.10
Trial 3, density corrected (mL)
 .
 .
10.5788
24.9926
49.4691
99.04
Mean (mL)
 .
 .
9.59382
24.8950
49.4426
99.06
Stdev (mL)
 .
 .
1.1465
0.0852
0.0285
0.03
%RSD
 .
 .
11.9509
0.3423
0.0576
0.03
Error (measured - mtated, mL)
 .
 .
-0.4062
-0.1050
-0.5574
-0.94
The table also shows calculated mean and standard deviation.
The correction factor was calculated to plot the burette graph using this formula
Correction Factor = Volume delivered – Volume indicated
Thereafter, a graph was plotted of Average Buret Correction Factor vs. Volume Delivered in Excel.
Figure 1 shows a burette graph
The Y axis was labeled with correction values in mL while x axis was labeled with delivered volume in mL.
Data analysis included calculation of mean values.
Mean was calculated using the formula
Mean = Trial1 + Trial2 + Trial3
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ———————– .
 .  .  .  .  .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 .
Percentage Relative Standard Deviation was calculated using the formula below
%RSD = SD/mean*100%
Conclusion
The allowable percentage error was +- 0.03 %.
The percentage error was calculated using the formula
 . (TV) – EV . X 100
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ———————– .
 .  .  .  .  .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TV .
Where TV is theoretical volume
EV is experimental volume
To improve on proper measurement of volumes, manual calibration of apparatus should be done regularly. To also improve on their performance, volumetric flasks, which are usually colorless, they might be amber-colored so as to handle most light-sensitive compounds.
References
1. Bucher, J. (2007).
