EXERCISE 80 



IS STARCH SOLUBLE IN WATER ? 



Materials. Powdered starch ; iodine solution ; test tubes. 



Directions. Put a small amount of starch in cold water in a test tube. Add sufficient iodine 

 solution to eolor the starch, and shake the mixture thoroughly. Set it aside and observe from time 

 to time, as the starch settles, to see whether any of the starch remains permanently and evenly 

 distributed throughout the water, as will be the case if the starch is dissolved. 



In another test tube place a small amount of starch in water and heat to a boiling temperature. 

 When cool, add a few drops of iodine solution. Set it aside until the following day. If the starch is 

 dissolved the liquid will remain colored throughout, but if the starch is not dissolved part or all of 

 the liquid will be clear. 



Additional problems. When using starch in laundry work the water in which the starch is placed is 

 usually heated. Why ? 



From the above experiments do you infer that starch can pass readily from one part of a plant to 

 another part? 



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