Chemistry practical

Clare Chong
P2

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Chemistry Practical 4: Measuring rate of reaction

Aim of experiment:
To determine the rate of reaction when the concentration of I2 increases.

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Chemical equation:
2Fe3+ + 2I- --> 2Fe2+ + I2

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Apparatus & materials:
Apparatus

Quantity

50ml Pipette

1

10ml Pipette

1

Pipette bulb

1

100ml beaker

2

50ml Burette

1

250ml Conical Flask

6

Timer

1

Distilled water

100ml or more

50ml Measuring Cylinder

1

Bottle of starch

1

S2O32-

100ml or more

Fe3+

50ml or more

I-

50ml or more

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Procedure:
! pipette 50ml of 0.02M Kl, 50ml of 0.02M Fe3+ into separate beakers.
1.
2. Prepare S2O32- solution in a burette.

3. Pour I- and Fe3+ solution into a conical flask. Start the timer.
4. For every 5 minutes, pipette 10ml of solution mixture into a flask, and 10ml of distilled water to quench the solution.
5. Add 3 drops of starch to the solution.
6. Then, proceed to titrate with S2O32-.
7. The solution will change from blue-black to a colourless solution.
8. Repeat steps 1 to 7 four more times, with different concentrations. (0.01, 0.005, 0.0025,

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0.00125)

Data:

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Experiment 1: 0.02M Kl
Volume of I-: 50ml
Volume of Fe2+ : 50ml

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Time/min

Volume of S2O3/cm3

Concentration of I-

0

-

5

0.00 - 20.6

20.6

0.02

10

20.6 - 36.1

15.5

0.02

15

00.00 - 17.6

17.6

0.02

20

17.6 - 30.4

12.8

0.02

25

30.4 - 44.7

14.3

Concentration l2 0.02

0.02

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Experiment 2: 0.01M Kl
Volume of I-: 50ml
Volume of Fe2+ : 50ml

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Time/min

Volume of S2O3/cm3

Concentration of I-

0

-

0.01

5

00.00 - 16.6

16.6

0.01

10

16.6 - 30.8

14.2

0.01

15

30.8 - 43.1

12.3

0.01

20

00.00 - 17.8

17.8

0.01

25

17.8 - 29.4

11.6

0.01

Concentration l2 Experiment 3: 0.005M Kl
Volume of I-: 50ml