1. Colorimetry Objectives:
Make up a standard copper (II) sulfate solution, whose concentration you know.
Construct a calibration graph.
Find the concentration of unknown copper (II) sulfate solutions.

2. Colorimetry

3. Make a standard CuSO4 solution
Step 1:
Make a standard CuSO4 solution

4. Colorimetry Weighing the solid
Weigh 6.24g of CuSO4.5H2O, add the powder to a beaker and dissolve in 50cm3 water.

5. Colorimetry Standard solution
Transfer solution to a 100cm3 volumetric flask and add more distilled water until the meniscus sits on the graduation line to make your 0.25M solution.

6. Colorimetry experiment
Step 2:
Colorimetry experiment

7. Colorimetry Colorimetry experiment
Coloured solutions absorb light that has passed through a filter. Darker solutions absorb more light.
Turn on the colorimeter, ensure the yellow filter has been selected.
Select ‘abs’ then place a cuvette filled with distilled water into the colorimeter.
Press ‘R’ for reference.
Add your 0.25M copper sulfate and press ‘T’ to record absorbance.
Repeat with 0.20M. 0.15M, ).10M and 0.05M solutions.

8. Colorimetry Calibration graph
Plot a calibration graph and find the unknown concentration of the solutions.
The technician said that: - unknown A/unknown 1 was M
- unknown B/unknown 2 was M x
Unknown 1 x
Absorbance x
Unknown 2 x x
0.075M
0.125M x
Concentration (moldm-3)

9. Colorimetry Colorimetry A very good quick video on the method:
A comparison of titrations and colorimetry: