Experiment 1: Mass, Volume, Density and Pasteur Pipette Calibration

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Laboratory Report
Experiment1: Mass, Volume, Density and Pasteur Pipette Calibration
Aims: the aim of the experiment was to calibrate a Pasteur pipette correctly so as to estimate the
mass and volume of a substance and eventually calculate its density.
Procedure
Part 1) calibration of the Pasteur pipette
1. Distilled water was added to 10 ml cylinder using a clean Pasteur pipette drop by drop
while controlling to avoid any excess on the walls of the cylinders to reduce water
remaining on walls of the cylinder. The amount of droplets was counted and the
observations recorded.
2. The cylinder was cleaned properly and the liquid disposed properly. The cylinder was dry
cleaned and the process was repeated again.
3. Step 1 was repeated but this time with a new pipette. The amount of droplets needed to
fill the cylinder were noted and compared with the first trial.
4. The tips of the pipettes were broken abut not at the same spot.
5. Step 1 was repeated using broken pipettes and the amount of droplets needed to fill the
cylinder were noted.

Part 2) Measuring of mass
1. Checked if the balance was clean
2. A weighing paper that had not been folded was placed on the weighing balance
3. The balance was carefully tared
4. 1.00g of sodium chloride was measured.
5. The solid together with the paper were carefully transferred to the beaker avoiding any
spills.
6. Step 4 was repeated but this time the weighing paper was folded. A comparison was
made to find out the most effective.
Part 3) Measurement of volume: calculation of Density.
1. A new 50ml beaker was placed on a clean balance then tared
2. The beaker was removed and the balance reset.
3. 10 ml distilled water was then added to the beaker
4. The mass of beaker and that of distilled water was then recorded.
5. The data obtained was the one to be used to calculate the density.
6. Steps 1-5 were then repeated but this time without a pipette.
7. The water was disposed in the sink and the glassware dried then prepared for the
subsequent steps.
8. 10 ml graduated pipette was used in repeating procedure of part one of the experiment
9. The density of the water was then compared in the previous glassware
Part 4) Estimating the density of organic liquid.

1. An empty capped 3ml vial was placed on a pan and the mass was recorded.0.50 ml of the
organic liquid was then drawn up.
2. The 0.500ml of the organic liquid was then released into a small amount back into the
reservoir .Made sure that the reservoir read 0.500ml and the liquid was then transferred to
the vial and the weight recorded.
3. The density was then calculated and cleaned the spilled liquid
4. Table 1B-1 was then used to determine the unknown liquid.
Observations
To find out if there is a difference in the drop rate, two Pasteur pipettes were used and then the
tip of one of them broken. Results showed that the pipette with a broken tip is faster in dropping
the liquid than the one which is not broken. Another unique observation was that whenever a
liquid is being transferred to another container, 0.1ml of the liquid would get lost and this can
lead to errors in the final results. To determine the best method to transfer a solid mass to a
container, unfolded and folded papers were used. The results indicated that using a folded paper
is much easier.
RESULTS
Part 1:
Pipette 1 Pipette 2
Original Pipette(Number of
drops to 1ml)
33 30
Broken Tip(Number of drops
to 1mL)
33 30