Colorimeter

1
Colorimeter

• a device used for colorimetry.

2
What does a colorimeter do?

• It is used to measure the concentration of
  coloured solutions.
• It compares a coloured solution with a clear
  solvent. This is to set the meter to zero.
• Known concentrations are used as
• reference solutions.

3
What makes up a colorimeter?

• a light source
• an aperture
• a set of filters in different colours
• a detector which measures the light which has
  passed through the solution
• A meter

4
How does it work?

• In a colorimeter a light is shone through a
  solution and the amount of light that gets
  through is detected on the other side by a
  light-sensitive cell.

5
What results does it produce?

• The reading from a colorimeter can measure
• transmission (how much light gets through)
• or
• absorbance (how much light gets absorbed).

6
The Beer-Lambert law

• When the concentration of the solution is high,
  it absorbs more light.

7
How are the results used?

• A calibration graph is needed to convert
  absorbance measurements to concentrations.
• Concentration on the x axis against absorbance on
  the y axis.

8
Uses of a colorimeter

• Analysis of air quality, contaminated land, water
  quality.
• To measure the concentration of salt.