Practical analysis of the copper content in a brass sample, the concentration of bicarbonate in bottled water, and the determination of iron content in an iron tablet.
Understandings of primary and secondary standard solutions
Unit 19 Assignment 1 – Practical Chemical Analysis
The percentage of copper in brass
This was the first experiment that was performed for this assignment. It
consisted of using the following equipment:
- 0.65g of brass
- 50cm3 beaker
- 5cm3 of concentrated nitric acid
- 10cm3 volumetric flask
- Distilled water
- Stopper
- Weighing balance
- 12.26g of hydrated copper sulfate
- Large beaker
- Stirrer
- 100cm3 volumetric flask
- Graduated pipettes
- 300g weight
- 0.5 mol dm-3 CuSO4(aq)
- Colorimeter
There were two parts to completing this analysis as it required us to first create a
brass solution and then determining the copper content of the solution by using
colorimetry.
Part one – the preparation of a brass solution
1) Firstly, the weighing balance was calibrated to ensure that the correct
values were shown. This was completed by using a weight with a set mass
of 300g to ensure that the balance worked. Once this was completed, an
accurate mass of 0.6g – 0.8g of brass was measured into a 50cm 3 beaker.
The approximate mass of brass that was used
for this experiment was 0.65g.
2) Next, the beaker containing the 0.65g of brass was taken into a fume
cupboard where 5cm3 of concentrated nitric acid was added into the
beaker. The solution was then left there to completely dissolve.
,Unit 19 Assignment 1 – Practical Chemical Analysis
3) Once the solution had dissolved entirely, it was then accurately
transferred into a 10cm3 volumetric flask. The beaker was then rinsed out
with a few drops of distilled water to ensure that all of the remaining
solution was transferred into the
volumetric flask.
4) Distilled water was then added to the volumetric flask to fill the volume to
the full 10cm3 line that was marked on the side. A stopper was then placed
onto the flask so it could be inverted a few times to ensure that the
solution was thoroughly mixed.
, Unit 19 Assignment 1 – Practical Chemical Analysis
Part two – the determination of copper content by colorimetry
1) Firstly, the weighing balance was calibrated once again by using the 300g
mass to ensure the correct values were shown. Once this was completed,
an approximate mass of between 11.98g – 12.50g of hydrated copper
sulfate was measured out into a large beaker. The approximate mass of
the hydrated copper sulfate that was used for this experiment was 12.26g.
2) Next, 50cm3 of distilled water was added to the large beaker containing
the hydrated copper sulfate. A stirrer was then used to completely
dissolve the copper sulfate.
3) Once this was completed, the solution was transferred into a 100cm 3
volumetric flask. The flask was then filled to the complete 100cm 3 volume
line with distilled water.
4) By using graduated pipettes, a serial dilution of 0.1, 0.2, 0.3, 0.4 of a
standard solution of copper (II) sulphate in 10cm 3 volumetric flasks using
0.5 mol dm-3 CuSO4(aq).
5) A cuvette was then filled at least half-full with the 0.1M standard solution
created from the serial dilution. The outer surface of the cuvette was
cleaned with a tissue and placed into the sample compartment of the
colorimeter.
6) The absorbance reading was then recorded and the concentration of
copper along with the percentage of the copper content was then
calculated.
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