Download The Mystery Powder Challenge Background Information

The Mystery Powder Challenge
Background Information
1. Define chemical change –
2. Define physical change –
3. Describe visible signs of a chemical
change –
4. Describe some examples of a physical
change -
Lab Questions/Goals
1.
Which chemical changes identified compounds?
2.
Which physical changes identified compounds?
3.
What are the unknown powders?
Process
1.
Perform 5 tests on each powder
1.
2.
3.
4.
5.
2.
3.
Cold water
Warm water
Rubbing alcohol
Vinegar
iodine
Compare your results to a table of properties
Repeat tests with questionable results if time
Table of Observations
Test
Solution
Unknown
Powder
Negative
control
A
B
C
D
E
F
Cold
water
Warm
water
Alcohol Vinegar iodine
Table of Properties, part I
Powder
Sodium
bicarbonate
Cold Warm Alcohol Vinegar iodine
water water
+
+++
+
-
sucrose
+
+++
-
-
-
Sodium
chloride
amylose
+
+
-
-
-
-
-
-
-
+
Table of Properties, part II
Powder
Calcium
carbonate
Magnesium
sulfate
Calcium
sulfate
Cold Warm Alcohol Vinegar iodine
water water
+
+
+++
+
-
-
-
-
-
-
-
What were those white powders?
A.
B.
C.
D.
E.
F.
G.
Amylose (corn starch)
Sodium chloride (table salt)
Sucrose (table sugar)
Sodium bicarbonate (baking soda)
Calcium carbonate (chalk)
Magnesium sulfate (epsom salts)
- control = calcium sulfate (plaster paris)
Analysis & Conclusions
1. Label each example as either a chemical
change or a physical change.
a.
b.
c.
d.
2.
3.
Vinegar causes baking soda to foam
Iodine changes color when mixed with corn starch
Epsom salt dissolves in both alcohol and water
Sugar dissolves much better in warm water than
cold water
Which powders did you successfully identify?
Which single test would be most effective to
identify:
a.
b.
c.
d.
Baking soda
Corn starch
Chalk
Epsom salt