#_______
Name:_______________________
What’s The Matter? The Identification of an Unknown Substance
Purpose
The purpose of this investigation is to learn to identify the properties of starch, sugar, baking soda, and
salt.
Materials
 Metal spatula
 Wash bottle
 Hot Plate
 Pipettes (plastic eye droppers)
 Aluminum foil- a disposable surface to
heat the solid on
Reagents
 Water
 Vinegar (a weak acid)
 Iodine (a reagent used to test for starch)
 Corn starch


Acetate sheet- a surface for reacting
chemicals
Plastic cup- to mix chemicals with
water to check for solubility and
Stirring rod



Baking soda
Salt
Sugar

Procedure(s)
Day One
1. Place about 20 mL of water into a small beaker. Obtain a small sample of starch on the tip of a
spatula. Add the starch to the water, stirring with a glass rod. Record your observations regarding
the solubility of starch in water. Rinse and dry the beaker.
2. Place a small sample of starch onto a clean sheet of acetate. Add 5 drops of vinegar. Record your
observations.
3. Place another small amount of starch onto a clean region of the acetate. Add 5 drops of iodine
solution. Record your observations.
4. Obtain a 5 cm x 5 cm square of aluminum foil. Place a pea sized amount starch (using a scoopula)
onto the foil. Place the foil on a hot plate, using tongs, for about 2 minutes. Record your
observations regarding the melting point of starch in the data table.
5. Repeat steps 1- 4, using sugar instead of starch. Then conduct the same tests on baking soda and
on salt.
6. Transfer your data onto the day two document and turn it (Day Two Document) in to your
instructor.
Substance
Starch
Sugar
Baking soda
Salt
Solubility in
water
Reactivity with
acid
Reaction with
iodine
Reaction to heating
#_______
Name:_______________________
What’s The Matter? The Identification of an Unknown Substance
Unknown # ___________
Day One Data Table
Substance
Solubility in
water
Starch
Reactivity with
acid
Reaction with
iodine
Reaction to heating
Sugar
Baking soda
Salt
Purpose
The purpose of this experiment is to identify an unknown substance using chemical and physical
properties.
Safety Precautions
List 3
 Wear PPE (goggles and apron).
Materials
 Metal spatula
 Hot Plate
 Pipettes (plastic eye droppers)
 Aluminum foil- a disposable surface to
heat the solid on



Acetate sheet- a surface for reacting
chemicals
Plastic cup- to mix chemicals with
water to check for solubility
Stirring rod
Reagents
 Water
 Vinegar (a weak acid)
 Iodine (a reagent used to test for starch)
 Unknown Powders 1, 2, 3, 4
Procedures
Day Two (Please note you will write down the procedures you followed)
1. Obtain an unknown from your teacher. Your assigned number is listed for you.
2. Based on qualitative observations with the naked eye, write a hypothesis answering the questionWhat is the identity of the unknown substance. Remember your hypothesis should be in an
if/then/because format. Raise your hand for the instructor before continuing.
3. Conduct the solubility test, the reaction with iodine and vinegar, and response to heating on the
unknown. Be sure to record your observations in the data table provided.
#_______
Name:_______________________
4. Clean up your lab area.
Data Table
Substance
Solubility in
water
Reactivity with
acid
Reaction with
iodine
Reaction to heating
Unknown #___
Trial 1
Trail 2
(On Your Own Paper)
Data Analysis
Write an analysis of the data you have recorded. (What is the distinguishing feature from the data of
the unknown substance?)
Conclusion
State which unknown # you were given to analyze.
Restate your hypothesis.
State whether or not your hypothesis was correct. Justify your position. Use evidence from the data
table to support your conclusion.