# write an article on calibration of glassware Paper must be at least 500 words.

Introduction

The main goal of this exercise is to calibrate these volumetric glass wares:

• 50 mL burette

•10 mL pipette

•25 mL pipette

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 &amp. 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

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

Density of water (at 21 degrees C in gm/L):

1.0030

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

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

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

Density of water (at 21 degrees C in gm/L):

&nbsp.

&nbsp.

&nbsp.

1.0030

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

&nbsp.

10mL pipette

25mL pipette

Empty Wt.(g)

&nbsp.

&nbsp.

29.2307

29.2307

36.4715

64.07

Trial 1, water + glassware (g)

&nbsp.

&nbsp.

39.1278

54.1623

86.0322

163.41

Trial 2, water + glassware (g)

&nbsp.

&nbsp.

37.5909

54.1406

86.0661

163.47

Trial 3, water + glassware (g)

&nbsp.

&nbsp.

39.8412

54.2983

86.0890

163.41

Trial 1, density corrected (mL)

&nbsp.

&nbsp.

9.8675

24.8570

49.4125

99.04

Trial 2, density corrected (mL)

&nbsp.

&nbsp.

8.3352

24.8354

49.4463

99.10

Trial 3, density corrected (mL)

&nbsp.

&nbsp.

10.5788

24.9926

49.4691

99.04

Mean (mL)

&nbsp.

&nbsp.

9.59382

24.8950

49.4426

99.06

Stdev (mL)

&nbsp.

&nbsp.

1.1465

0.0852

0.0285

0.03

%RSD

&nbsp.

&nbsp.

11.9509

0.3423

0.0576

0.03

Error (measured – mtated, mL)

&nbsp.

&nbsp.

-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

&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp. ———————–&nbsp.

&nbsp. &nbsp. &nbsp. &nbsp. &nbsp. &nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.3&nbsp.

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

&nbsp. (TV) – EV&nbsp. X 100

&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp. ———————–&nbsp.

&nbsp. &nbsp. &nbsp. &nbsp. &nbsp. &nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp.&nbsp. TV&nbsp.

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).