Real Lab Procedure
Place a potato on a tile.
Grind or chop the potato into small pieces, using a knife.
Using a spatula transfer these pieces of potato into a beaker.
Pour some distilled water into the beaker.
Place the beaker containing the mixture over a hot plate.
Heat the mixture for 5 minutes while continuously stirring it with a glass rod.
Take another beaker and cover its mouth with a muslin cloth.
Secure the muslin cloth around the mouth of the beaker by tying it with a thread.
Filter the solution through this beaker.
Now take a clean test tube and pour some of the filtrate into it.
Take a few drops of iodine solution using a dropper.
Add a couple of these drops into the test solution.
Simulator Procedure (as performed through the Online Labs)
You can select the type of test from the ‘Select type of the test’ drop down list.
To select a particular food sample, click on the corresponding icon.
Click and drag the dropper towards the food sample to pour a few drops of Iodine solution into the test sample.
Then drag the dropper back to place it in the Iodine bottle.
Based on your observation, you can indicate the presence of starch in the selected sample by clicking on the 'Yes' or 'No' radio button.
You can redo the experiment by clicking on the ‘Reset’ button.
Note: If the solution turns to blue-black colour it indicates the presence of starch in the solution.
The test solution turns blue-black in colour.
Iodine reacts with starch to form starch/iodine complex which has a blue-black colour. The appearance of blue-black colour confirms the presence of starch in the given food sample.
While using iodine solution, be careful, as it is toxic if swallowed or inhaled.
While heating, care should be taken that the solution does not splash on your face.