White Powders
Development of Critical Thinking Skills


I. Introduction: You will use samples of five white powders to collect and record data. You will also be given an UNKNOWN sample and from the observations that you have made - you should be able to determine the white powders contained in the unknown.

II. Materials: baking powder, salt, cornstarch, talcum powder, baking soda, salt, saran wrap, 8 1/2" x 11" sheet of paper, vinegar, water, iodine, droppers, hand lens.

III. Procedures: Place a sample of each white powder on a separate designated area of your worksheet covered by saran wrap.

NEVER TOUCH OR TASTE CHEMICALS IN THE LABORATORY!!

Physical Properties:
Briefly describe what each powder looks like using the magnifying lens.

a. baking powder-

b. cornstarch-

c. talcum powder-

d. baking soda-

e. salt-

Chemical Properties:
Test each sample for a reaction with ONE drop each of water, iodine, and vinegar. Record each reaction in the data below.
White Powder water Iodine vinegar
________________________________________________________________________
a. baking powder


b. cornstarch


c. talcum powder


d. baking soda


e. salt
You will now be given an UNKNOWN substance. Your UNKNOWN is ______. It may be made of 2 or 3 of the above 5 solids. Test with one drop of vinegar, iodine, and water. Record your observations below.
UNKNOWN water iodine vinegar



From your work above, what do you think (predict) is in the unknown?
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