PAG 05 - Colorimeter

Question 1

What does a colorimeter measure?

Answer 1

Absorbance/transmission.

The paler the solution, the lower the absorbance and higher the transmission, as more light can pass through the sample

Question 2

Outline the procedure to find an unknown concentration of reducing sugar.

Answer 2

1. Carry out a Benedict’s test on a range of standard solutions of reducing sugar.
2. Using the colorimeter, measure the percentage transmission for each sample.
3. Plot a graph of transmission against reducing sugar concentration.
4. Carry out a Benedict’s test on the unknown solution and measure the
   transmission using the colorimeter.
5. Plot the transmission on the calibration curve, and read off the x axis
   (reducing sugar concentration) for the concentration of the unknown solution.

Question 3

What indicates a higher reducing sugar concentration?

Answer 3

Higher absorbance, lower transmission.