Lab report calibration of volumetric flask

Topics: Measurement, Laboratory glassware, Metrology Pages: 12 (2025 words) Published: October 13, 2013
OBJECTIVES

The objective of the experiment was
To calibrate a 10 mL volumetric pipette
To calibrate a 25 mL volumetric pipette
To calibrate a 100 mL volumetric flask
To calibrate a 50 mL measuring cylinder

INTRODUCTION

The purpose of this experiment is to study the relationship of several types of volumetric glassware and the accuracy of measuring the volumes of liquids very precisely in quantitative laboratory work. The accuracy of the measurement the volumes is the degree of closeness of measurements of a quantity’s actual volumes while the precision of the volumes is the degree to which repeated measurements under unchanged conditions show the same results. Each of volumetric glassware is marked with its total volume, the notation of TD for ‘to deliver’ and TC for ‘to contain’ and also with the temperature at which the calibration applies. For greatest accuracy, volumetric glassware should be calibrated to measure the volume that is actually contained in or delivered by a particular piece of glassware. The calibration is done by measuring the mass of water contained in or delivered by the glassware. The density of water at a particular temperature is used to convert mass into volume. Pipettes and burettes are calibrated to deliver specific volumes whereas, volumetric flasks are calibrated to contain basis.

MATERIAL AND PROCEDURE

The materials used in the experiment were:-
10 mL volumetric pipette
25 mL volumetric pipette
100 mL volumetric flask
50 mL measuring cylinder
Distilled water
Plastic dropper
100 mL beaker
250 mL beaker
The procedure
1. Calibration of a volumetric pipette ( 10 mL and 25 mL )
a) An empty 100ml beaker was weighed to the nearest milligram using electronic weigh balance. b) The 10ml pipette was filled to the mark with distilled water. c) The water was drained by gravity (remove pipette bulb or pump) into the beaker and caps the bottle to prevent evaporation. d) The bottle was weighed again to find the mass of water delivered from the pipette. e) Then used the following equation to convert mass to volume. f) The above procedure was performed on each of the pipette. g) The experiment was repeated for 2 times.

True (actual) Volume = (grams of water) x (volume of 1 g of H20 in Table 1

2. Calibration of a volumetric flask (100ml)
a) An empty 100ml volumetric flask was weighed to the nearest milligram using electronic weigh balance. b) The flask was filled to the mark with distilled water and weighed again. c) The mass of water contained in the flask was calculated.

d) Then convert the mass of water to volume.
e) The procedure was repeated two times again.

3. Calibration of a measuring cylinder
a) An empty 50ml measuring cylinder was weighed to the nearest milligram using electronic weigh balance. b) The measuring cylinder was filled to the mark with distilled water and weighed again. c) The mass of water contained in measuring cylinder was calculated. d) Then convert the mass of water to volume by the procedure you think most appropriate. e) Repeat the experiment for two times.

RESULTS AND DISCUSSION
I. 10mL pipette

Trial 1

Trial 2

Trial 3
Mass of container + water (g)
59.31
59.34
59.28
Mass of container (g)
49.55
49.56
49.54
Mass of water (g)

9.76
9.78
9.74
Temperature (°C)
32
32
32
Actual volume (mL)
9.82
9.84
9.80
Average volume (mL)

9.82
Standard deviation, σ
0.02
Relative standard deviation (σ/
2.036666×10-3

II. 25ml pipette

Trial 1

Trial 2

Trial 3
Mass of container + water (g)
74.06
74.04
74.25
Mass of container (g)
49.56
49.55
49.54
Mass of water (g)

24.50
24.49
24.71
Temperature (°C)
32
32
32
Actual volume (mL)
24.64
24.63
24.85
Average volume (mL)

24.71
Standard deviation, σ
0.1243
Relative standard deviation (σ/
5.0304 × 10-3

III. 100mL volumetric flask

Trial 1

Trial 2

Trial 3
Mass of container + water (g)
165.61
165.57...
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