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.