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1.3

Minor Versionm

by Suhail Ahanger

Introduction

Add a few drops of iodine to boiled rice with and without saliva and compare the results.

Video Overview

    • Iodine solution and dropper (pipette) should be handled carefully

    • Please do not ingest any of the materials

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  1. Take a spoon of cooked rice or any starch containing food on a plate. Potato is aslo fine.
    • Take a spoon of cooked rice or any starch containing food on a plate. Potato is aslo fine.

    • You may mash-up the cooked rice or potato.

    • Add some water to make a thin paste.

    Vishal:

    (1) All steps have been compressed into one. There should have been separate steps and photos for:

    - take test tubes and label (actually label them as A and B)

    - put potato and water....

    - add saliva....

    (2) Why are test tubes not labelled in the photos?

    Procheta Mallik - Reply

    • Filter the liquid using using any sort of funnel and a filter paper into a transparent container.

    • Separate the liquid into 2 test tubes labelled as A & B.

    • Add adequate saliva into Test tube B and leave test tube A as it is.

    Vishal:

    (1) Top portion of tube B is brown in photo. That is not okay. Let's mix well and retake photos.

    Procheta Mallik - Reply

    • Now add a 4-5 drops of iodine solution into both the test tubes.

    • Shake the containers and leave the containers for 15mins

    • Blue-black colour in test tube A, confirms the presence of starch in the food

    • Test tube B with saliva will slowly turn colourless, confirms breakdown of starch into sugars

    • You may also conduct the experiment such that you leave the containers for 20 min and then add the iodine solution

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    • Make sure sufficient time is given for the saliva to act

    • Make sure the food mixes well with the water and saliva

    • Too much iodine might produce a negative result; add only 4-5 drops.

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    • Why does the mixture with saliva turn colourless? What's there in our saliva that's acting on the starch in the food?

    • Can you list out some sources of starch after conducting this experiment with various food items?

    • What role does iodine play in this experiment?

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Finish Line

Kailash NR

Member since: 05/02/2017

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