Kinetics Study on the Reaction between Potassium iodate and Sodium Sulphite

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.

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