Practical 7 Iodine clock

Question 1

Stage 1 prep

Answer 1

1a Measure (suitable/known volumes of) A, B and C (ignore quoted values for volume)
1b Use of colorimeter
1c into separate container(s) – (allow up to two reagents measured together into one container) – ignore use of X

Question 2

Stage 2 procedure

Answer 2

2a Start clock/timer at the point of mixing
2b Take series of colorimeter readings at regular time intervals
2c Use of same concentration of B and C
2d Same temperature
2e Repeat with different concentrations of A (can be implied through different volumes of A (whichever it is with respect to) and same total volume)

Question 3

Stage 3 use of results

Answer 3

3a Plot absorbance vs time and measure/calculate gradient at time=0
3b plot of gradient against volumes/concentrations of A
3c description of interpreting order from shape of 1/time vs volume or concentration graph