Colorimetry
The aim of this practical is to prepare standard solutions by dilution, to calibrate the colorimeter
and then find the concentration of an unknown Cu 2+ solution.
To find the concentration of the unknown Cu 2+ solution, we began by switching on the colorimeter,
and ensured that the filter was set to 680nm (red filter). Six beakers were labelled as: 0.2 ; 0.4 ; 0.6 ;
0.8 ; 1.0. Using the table below as a guide, the Copper II solution and distilled water were both
measured using the pipettes.
Copper II concentration Volume of Copper Volume of distilled water
(moldm-3) (cm3) (cm3)
1.0 10.0 0.0
0.8 8.0 2.0
0.6 6.0 4.0
0.4 4.0 6.0
0.2 2.0 8.0
0.0 0.0 10.0
After filling the six beakers, the colorimeter was set to %Transmission. A cuvette was filled with 0.0
moldm-3 of the solution, while setting the %Transmission to 100%. The other cuvettes were also filled
with the other solutions and were placed into the colorimeter. The %Transmission was recorded for
each of the cuvettes. The 0.0 moldm-3 cuvette was regularly placed back into the colorimeter to
ensure that the %Transmission was still at 100%.
Then another cuvette was filled with the unknown solution - the absorbance and the %Transmission
were measured.
The experiment was repeated – this time, the filter was changed to the 590nm filter (orange filter).
Results:
Copper II 680nm RED Filter 590nm ORANGE Filter
Concentration Absorbance %Transmission Absorbance %Transmission
moldm-3
1.0 0.74 18 0.25 58
0.8 0.58 27 0.18 65
0.6 0.48 33 0.16 70
0.4 0.33 48 0.13 74
0.2 0.18 67 0.07 87
0.0 0.0 100 0.0 100
Unknown 680nm RED Filter 590nm ORANGE Filter
The aim of this practical is to prepare standard solutions by dilution, to calibrate the colorimeter
and then find the concentration of an unknown Cu 2+ solution.
To find the concentration of the unknown Cu 2+ solution, we began by switching on the colorimeter,
and ensured that the filter was set to 680nm (red filter). Six beakers were labelled as: 0.2 ; 0.4 ; 0.6 ;
0.8 ; 1.0. Using the table below as a guide, the Copper II solution and distilled water were both
measured using the pipettes.
Copper II concentration Volume of Copper Volume of distilled water
(moldm-3) (cm3) (cm3)
1.0 10.0 0.0
0.8 8.0 2.0
0.6 6.0 4.0
0.4 4.0 6.0
0.2 2.0 8.0
0.0 0.0 10.0
After filling the six beakers, the colorimeter was set to %Transmission. A cuvette was filled with 0.0
moldm-3 of the solution, while setting the %Transmission to 100%. The other cuvettes were also filled
with the other solutions and were placed into the colorimeter. The %Transmission was recorded for
each of the cuvettes. The 0.0 moldm-3 cuvette was regularly placed back into the colorimeter to
ensure that the %Transmission was still at 100%.
Then another cuvette was filled with the unknown solution - the absorbance and the %Transmission
were measured.
The experiment was repeated – this time, the filter was changed to the 590nm filter (orange filter).
Results:
Copper II 680nm RED Filter 590nm ORANGE Filter
Concentration Absorbance %Transmission Absorbance %Transmission
moldm-3
1.0 0.74 18 0.25 58
0.8 0.58 27 0.18 65
0.6 0.48 33 0.16 70
0.4 0.33 48 0.13 74
0.2 0.18 67 0.07 87
0.0 0.0 100 0.0 100
Unknown 680nm RED Filter 590nm ORANGE Filter
