Clock reactions

Question 1

What do you measure in a clock reaction?

Answer 1

How the time taken for a set amount of product to form changes as you vary the concentration of one of the reactants

Question 2

What assumptions do you need to make when you do a clock reaction?

Answer 2

• The temperature remains constant
• The concentration of each reactant doesn’t change significantly over the period of time of your clock reaction
• When the endpoint is seen, the reaction has not proceeded too far

Question 3

What is the ionic equation for the iodine clock reaction?

Answer 3

H2O2 + 2I- + 2H+ -> 2H2O + I2

Question 4

What indicator is used in the iodine clock reaction?

Answer 4

Starch

Question 5

What colour change is seen with the starch if the iodine is present?

Answer 5

Turns blue-black

Question 6

What concentrations do you change in the iodine clock reaction?

Answer 6

Iodine

hydrogen peroxide