Unit 1 PPA 2

Question 1

What is colorimetry used to do?

Answer 1

Work out the concentrations of coloured substances in a solution.

Question 2

What colour is the filter in a colorimeter?

Answer 2

Complementary to that of the solution for maximum absorbance

Question 3

What is the complementary colour to purple?

Answer 3

Green

Question 4

Why is the heating of a paperclip with dilute nitric acid carried out in a fume cupboard?

Answer 4

Brown fumes of nitrogen dioxide are evolved

Question 5

After the manganese has been oxidised to Mn2+ ions by the nitric acid, what further oxidises the manganese to MnO4-?

Answer 5

Acidified potassium periodate

Question 6

Name the main errors in the experiment

Answer 6

-Incorrect measurements when diluting the potassium permanganate solution, therefore creating errors of the graph values.
_ Incorrect drawing of the line of best fit on the calibration graph.
- Not all the manganese in the steel clip may have been oxidised to MgO4- ions