Conclusions that can be drawn from the data is that when the concentration of the potassium iodate solution was increased the rate of reaction decreased. There is no warning of when the blue colour is about to appear. The effect of concentration and temperature on reaction rate. Our new website is coming soon. Teaching notes Visual tips: Lastly a limitation in part B is that a final temperature for the solution could not be measured because of all of the surrounding influences such as holding the tube would have transferred heat to the solution.
See Technician notes about using dilute ethanoic acid as a less hazardous alternative Both solutions are colourless although solution A will be slightly cloudy. Answers Clock Iodine lab Reaction. Additional notes 1 Hydrogen peroxide is capable of oxidising thiosulfate ions to tetrathionate ions but the reaction is too slow to affect this demonstration. This is one of a number of reactions loosely called the iodine clock. A chemical stop-clock – iodine clock reaction. As soon as the iodine is formed, it reacts with the thiosulfate to form tetrathionate ions and recycles the iodide ions by the fast reaction:
See Technician notes about using dilute ethanoic acid as a less hazardous alternative. See Technician notes about using dilute ethanoic acid as a less hazardous alternative Both solutions are colourless although solution A will be slightly cloudy. There is no warning of when the blue colour is about iodune appear.
Pour onto this approximately cm 3 of boiling water and stir. Our new website is coming soon.
The Iodine Clock Investigation – GCSE Science – Marked by
The final rate law determined was:. It can be used to stimulate discussion about what factors affect the rate of reaction.
It may help understanding if the students are already familiar with the reactions of starch and iodine, and iodine and sodium thiosulfate, so it may be worth demonstrating these beforehand. Stir until all the solids have dissolved and allow to cool to room temperature. Solids, liquids and gases. Eye protection Balance 1 or 2 d. Jump to main content. Ensure thorough mixing with a stirring rod or magnetic stirrer. Instead of the iodate ion ioddine being changed the concentration of the bisulfate could have been changed by making it the limiting reactant in the balanced equations.
The Iodine Clock Investigation
This is one of a number of reactions loosely called the iodine clock. The demonstration f Measure cm 3 of solution A idoine cm 3 of solution B in separate cm 3 measuring cylinders. This demonstration can be used at secondary level as an introduction to some of the ideas about kinetics. The order of reaction with respect to the iodate ion, mmust be determined for the following rate.
Iodine Clock Reaction Lab Answers
Solution A is made up as follows: Apparatus Chemicals Eye protection Balance 1 or 2 d. Lesson organisation Experimsnt demonstration can be used at secondary level as an introduction to some of the ideas corsework kinetics. Page last updated October A solution of hydrogen peroxide is mixed with one containing potassium iodide, starch and sodium thiosulfate.
As soon as all the thiosulfate is used up, free iodine or, strictly, I 3 – ions remains in solution and reacts with the starch to form the familiar blue-black complex. The slope represents the order of reaction with regards to the iodate, but the actual value is 2.
Schoolworkhelper Editorial Team https: The basic reaction is: The experiment should have been done both ways to have the most accurate results. For a student investigation, the quantities required would be smaller but volumes then need to be measured quite accurately with, for example, disposable plastic syringes.
Sodium thiosulfatewater, Na 2 Iodkne 2 O 3.
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