How to recognize starch

You urgently need to cook the paste, and you remember that somewhere in the closet was the starch? But on the shelves revealed several packages of white powder - which one to use? Determine this is possible by chemical means. Suitable for determination of starchand a substance probably have in your home medicine Cabinet.

You will need

• Alcoholic solution of iodine
• Pipette
• Saucer or glass outlet
• The concept of reactia and indicator

Instruction

1. Carefully open the package with white powder. Type it with a spoon and place on a saucer or in a chemical test tube. In this case, no matter whether fall into the vial moisture, but in General dishes should be dry.
2. Clean and dry pipette, type a drop of an alcoholic solution of iodine. Drop of iodine on a white powder. If the powder contains starch, the powder from white to dark blue or even purple, depending on the concentration of iodine. Starch and iodine always react on each other in a similar way, so the chemistry books write that the iodine is recation for the presence of starch, and starch is a digital counter of the presence of iodine.
3. In addition, experience with the starchohms and iodine is a great way to interest children chemistry. Check which foods have starch. For a home experiment children can be, for example, take a potato, Apple, piece of bread. Potato or Apple must to be cut, and from bread to make a lump. To determine which product the starchand most of all. It's easy to figure out, if you take iodine the same concentration. Starch more where the blue color will be more intense.