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How to recognize starch paste

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Iodine can be replaced with potassium iodide or lyugol</a>

It is possible to imagine a situation in whichMan is several containers with indistinguishable colloidal solutions of starch, carbomethylcellulose, pectin or agar. Remember the school chemistry course.

One of the qualitative reactions of starch and the only one that gives a visible result is the coloration in blue when interacting with iodine.

Two other qualitative reactions do not give the expected effect, characteristic for carbohydrates in general.

Accordingly, it is more logical and easier to use iodine.

You will need

  • Pharmaceutical iodine, water, starch, glass container, saucepan / saucepan

Instructions

    1

Prepare in a separate glass container a weak solution of iodine. To do this, just take the drug iodine and dilute it with water.

    2

Prepare Starch paste - colloidal starch solution in water. Take two teaspoons of starch, and a glass of cold water. A little cold water (about one third of the glass) is mixed in a pan with starch. Boil the rest of the water. Stir the mixture well, and get the starch milk. With stirring, add boiling water to it and, while stirring, heat on the fire until the solution becomes clear. Cool it down. This is starchy paste, Which so well glues paper, so it is often used, for example, for gluing wallpaper.

    3

Dip a bit of iodine solution into the finished starch paste. At the point of contact of the solution and pasteAnd a blue color appears. If the concentration of iodine is very high, you will get a color from violet to black.

How to recognize starch paste Was last modified: June 21st, 2017 By Sexzeilt
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