The Calibration of Graduated Volumetric Glasswares
Added on 2022-02-04
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Chemistry
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EXPERIMENT NO. 1
The Calibration of Graduated Volumetric Glasswares
Lumbo, E. V.
1.0 Introduction
Calibration is a procedure that establishes the relationship between quantity scales
indicated by a measuring instrument under specified condition. It determines accuracy
of the measured data and provides the traceability to the measurement. Every
measuring instrument has its standards in order for it to be said as calibrated (UNIDO,
2006). Volumetric glassware for example is container that can be calibrated. It is done
by measuring the mass of liquid contained in or delivered then computing for its volume
with the use of liquid’s known density. Correction for buoyancy must be considered in
calibration because air buoyancy causes an object’s weight lighter than its weight in
vacuum (Harvey 2000). The objective of this experiment was to study the methods of
calibrating volumetric glassware through quantitative laboratory work.
2.0 Experimental
Volumetric pipet, volumetric flask, and acid buret were the glassware calibrated in this
experiment. The materials used were analytical balance, top loading balance, and
Erlenmeyer flask. The only reagent was water.
The Calibration of Graduated Volumetric Glasswares
Lumbo, E. V.
1.0 Introduction
Calibration is a procedure that establishes the relationship between quantity scales
indicated by a measuring instrument under specified condition. It determines accuracy
of the measured data and provides the traceability to the measurement. Every
measuring instrument has its standards in order for it to be said as calibrated (UNIDO,
2006). Volumetric glassware for example is container that can be calibrated. It is done
by measuring the mass of liquid contained in or delivered then computing for its volume
with the use of liquid’s known density. Correction for buoyancy must be considered in
calibration because air buoyancy causes an object’s weight lighter than its weight in
vacuum (Harvey 2000). The objective of this experiment was to study the methods of
calibrating volumetric glassware through quantitative laboratory work.
2.0 Experimental
Volumetric pipet, volumetric flask, and acid buret were the glassware calibrated in this
experiment. The materials used were analytical balance, top loading balance, and
Erlenmeyer flask. The only reagent was water.
Table 1: Correction for buoyancy (stainless steel weights) and change in container
volume applied
2.1 Calibration of Volumetric Pipette
Erlenmeyer flask was first weighed at analytical balance. The temperature-equilibrated
water was transferred to flask with the use of volumetric pipet. Then, flask with its
content was then weighed at analytical balance. The mass of water was calculated by
finding the difference in these masses. Lastly, the mass was converted into volume with
the aid of Table 1. This procedure has been repeated three times and the mean volume
delivered and its standard deviation has been calculated.
volume applied
2.1 Calibration of Volumetric Pipette
Erlenmeyer flask was first weighed at analytical balance. The temperature-equilibrated
water was transferred to flask with the use of volumetric pipet. Then, flask with its
content was then weighed at analytical balance. The mass of water was calculated by
finding the difference in these masses. Lastly, the mass was converted into volume with
the aid of Table 1. This procedure has been repeated three times and the mean volume
delivered and its standard deviation has been calculated.
2.2 Calibration of Buret
Buret was first filled with temperature-equilibrated water. There should be no air bubble
trapped at the tip of the buret. The water was drained up to the 0.00mL mark. Then the
tip of the buret was touched to the wall of the beaker to remove adhering drop. After 10
minutes, the volume was checked. There should be no change that can be seen. A
125mL Erlenmeyer flask was weighed at analytical balance. Then, 5mL water was
delivered to the flask with the use of buret. The buret was refilled. The flask and its
contents were weighed. The mass of water was calculated by subtracting these
masses. This mass was converted to volume using Table 1. The apparent volume was
subtracted to the true volume obtained from the experiment. This difference was the
correction to the apparent volume to get the true volume. The calibration was repeated
until there is ±0.02mL agreement.
Plot of correction was done by repeating the procedure in the calibration of buret but
instead of just delivering 5mL, it was done by delivering 10mL to the receiver and then
5mL intervals over its entire volume.
2.3 Calibration of Volumetric Flask
Volumetric flask was first weighed at top loading balance. Then it was filled with
temperature-equilibrated water and reweighed. The corrected volume of water was
calculated the same manner as the calibration of volumetric pipet.
Buret was first filled with temperature-equilibrated water. There should be no air bubble
trapped at the tip of the buret. The water was drained up to the 0.00mL mark. Then the
tip of the buret was touched to the wall of the beaker to remove adhering drop. After 10
minutes, the volume was checked. There should be no change that can be seen. A
125mL Erlenmeyer flask was weighed at analytical balance. Then, 5mL water was
delivered to the flask with the use of buret. The buret was refilled. The flask and its
contents were weighed. The mass of water was calculated by subtracting these
masses. This mass was converted to volume using Table 1. The apparent volume was
subtracted to the true volume obtained from the experiment. This difference was the
correction to the apparent volume to get the true volume. The calibration was repeated
until there is ±0.02mL agreement.
Plot of correction was done by repeating the procedure in the calibration of buret but
instead of just delivering 5mL, it was done by delivering 10mL to the receiver and then
5mL intervals over its entire volume.
2.3 Calibration of Volumetric Flask
Volumetric flask was first weighed at top loading balance. Then it was filled with
temperature-equilibrated water and reweighed. The corrected volume of water was
calculated the same manner as the calibration of volumetric pipet.
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