Colourimeter

Question 1

A colourimeter is an instrument that beams a

Answer 1

specific wavelength (colour) of light through a sample and measures how much of this light is absorbed (arbitrary units)/ transmitted

Question 2

They provide a ……. measurement

Answer 2

quantitative

Question 3

They contain different wavelengths or colour filters (depends on the model of colourimeter), so that a

Answer 3

suitable colour can be shone through the sample and will not get absorbed. This colour will be the contrasting colour (eg. a red sample should have green light shone through)

Question 4

Remember that a sample will look red

Answer 4

as that wavelength of light is being reflected but the other wavelengths will be absorbed

Question 5

Colourimeters must be ………….. before taking measurements

Answer 5

calibrated

Question 6

How is the colourimeter calibrated

Answer 6

This is completed by placing a blank into the colourimeter and taking a reference, it should read 0 (that is, no light is being absorbed)

This step should be repeated periodically whilst taking measurements to ensure that the absorbance is still 0

Question 7

The results can then be used to plot a

Answer 7

calibration or standard curve
Absorbance against the known concentrations can be used
Unknown concentrations can then be determined from this graph

absorbance y glucose conc x