CALIBRATION OF VOLUMETRIC GLASSWARE
1. To calibrate a 10 mL volumetric pipette
2. To calibrate a 25mL volumetric pipette
3. To calibrate a 100mL volumetric pipette
4. To calibrate a 50mL measuring cylinder
1) Calibration of a volumetric pipette (10mL and 25mL)
(a) Pipette is used to transfer the water. If the distilled water does not drain uniformly will leaves droplets of water in the inner surface in the pipette. (b) The water used for calibration should be in thermal equilibrium and same temperature with the surroundings. The temperature should be recorded at uniform intervals. Weighing to the nearest milligrams will be satisfactory and the use of a top loading is sufficient. (i) Weigh an empty bottle to the nearest milligram.
(ii) Fill the pipette to the mark with distilled water
(iii) Drain the water by gravity into the weighing bottle and cap the bottle to prevent evaporation. (iv) Weigh the bottle again to find the mass of the water (v) Use the following equation to convert mass to volume: Actual Volume = grams of water × volume of 1 g of H2O
2) Calibration of a volumetric flask (100ml)
(a) Get a 100 ml volumetric flask. Make sure the flask is clean and dry. Weigh the flask to the flask to the nearest milligram.
(b) Fill the flask to the mark with distilled water and weigh again. (c) Calculate the mass of mass of water contained in the flask (d) Convert the mass of the water to volume
3) Calibration of a measuring cylinder (50ml)
Calculate the mass of water contained in the cylinder and convert it to volume by the procedure you think most appropriate. Temperature, °C| Volume, mL at T °C| 20| 1.0028|