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The White Powder Lab
Purpose: The purpose of this lab is to learn to identify the properties of starch, sugar, baking soda, and salt. You may consider testing the following variables:
 
    • solubility in water
    • reactivity with acid
    • the reaction to iodine solution (i.e. the starch test - a starch will blacken the presence of iodine)
    • the response to heating
 
Given an unknown mixture containing one or more of these compounds, it should be possible to identify which compounds are present in the unknown mixture.
 
Materials:
 
metal spatula
toothpicks
wash bottle
candle
matches
pipettes (plastic eye droppers)
aluminum foil squares  - a disposable surface to heat the solid on
acetate sheet - a surface for mixing drops of chemicals
optional: microscale conductivity tester
 
Reagents:
 
water
vinegar (a weak acid)
iodine (a reagent to test for starch)
corn starch
baking soda
salt
sugar
 
Procedure: You will design your own procedure. Write out, step by step, what you intend to do. It is suggested that you first test the known compounds, to determine how they behave. Once you have established the individual characteristics of starch, baking soda, salt, and vinegar, you can determine which of the compounds are present in the unknown mixture which has been assigned to you.
 
Data: Create your own data table(s).
 
Make sure that each table has a title. Be sure that the heading above each column is clearly labeled. The tables should be logical and well-organized.
 
Conclusion:
 
  • Summarize the individual behavior of each compound.
  • State which unknown number you were assigned.
  • Explain what is in your unknown mixture.
  • Is your conclusion fact or opinion? Use supporting experimental evidence to support and justify your prediction.



E Saylor

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