Materials Required

Procedure
Real Lab Procedure
- Take four 250ml conical flasks and label them as A, B, C and D.
- Add 2ml, 4ml, 6ml, and 8ml of 0.01 M potassium iodate (KIO3) solution to the flasks A, B, C and D.
- Add 10ml of 1M H2SO4 to each flask.
- Add water to bring the volume of the solution to 100ml in each flask.
- Add 5ml of starch solution to each flask.
- Add 10ml of 0.005 M sodium sulphite (Na2SO3) solution to each flask and start the stop watch immediately.
- Note the time when the blue colour just appears.
- Repeat the above 2 steps with the solutions of flasks B, C and D and note the time required in each case when the blue colour first appears.
Simulator Procedure (as performed through the Online Labs)
- You can select the volume of potassium iodate (KIO3) solution using the slider.
- Drag the conical flask containing 0.01 M potassium iodate (KIO3) solution to the measuring jar to measure the solution.
- Drag the measuring jar to the conical flask to pour the solution in it.
- Drag the bottle to the measuring jar to measure 10ml 1 M sulphuric acid.
- Drag the measuring jar to the conical flask to pour sulphuric acid in it.
- Drag the beaker to the measuring jar to measure distilled water.
- Drag the measuring jar to the conical flask to pour water in it.
- Drag the bottle to the measuring jar to measure 5 ml starch solution.
- Drag the measuring jar to the conical flask to pour the starch solution in it.
- Drag the bottle to the measuring jar to measure 10 ml 0.005 M sodium sulphite (Na2SO3) solution.
- Drag the measuring jar to the conical flask to pour sodium sulphite solution in it.
- You can get the time taken for the appearance of blue colour from the stopwatch.
- You can use the embedded worksheet to enter the values.
- You can plot a graph using the worksheet.
- To redo the experiment, click the ‘Reset’ button.
Note: Click on the ‘HELP’ button to see the instructions.
Observation
Flask
|
0.01 M KIO3 (ml) |
1 M H2SO4 |
Water |
Starch solution |
0.005 M Na2SO3 (ml) |
Time (t) for the appearance of blue colour (s) |
A |
2 |
10 |
88 |
5 |
10 |
|
B |
4 |
10 |
86 |
5 |
10 |
|
C |
6 |
10 |
84 |
5 |
10 |
|
D |
8 |
10 |
82 |
5 |
10 |
|
Conclusion
- The rate of reaction increases with increase in concentration of potassium iodate.
Precautions
- Always use a freshly prepared solution of sodium sulphite because it is easily oxidised by air.
- Concentration of KIO3 solution should be higher than the concentration of sodium sulphote solution.
- Use a freshly prepared starch solution.