UNKNOWN LAB
Name: ________________________________
SAFETY INFORMATION● DO NOT EAT THE IODINE. **Iodine is in group 17! It’s a Halogen - and is super reactive. DO NOT CONSUME.
○ You need small amounts in your body (if your body doesn’t absorb enough iodine, you can end up with a goiter… but most
salt sold in the USA is iodized, so you are most likely getting more than enough).
● Wash your hands as soon as you finish with the lab! You don’t want the iodine on your hands.
● liquid iodine will stain. Be careful.
____________________________________________________________________________________________________________________________________
Background Information:
When 2 or more substances are brought together, 1 of 3 things happens:
1. They react (or undergo a chemical change). This happens because bonds between atoms in the ___________________ (starting
materials) break, and new bonds form. At the end of a chemical change, you are left with ____________________ that have new
properties than the original substance.
a. Chemical changes happen because both reactants have the chemical property of reactivity with each other
2. One substance is dissolved in the other, forming a mixture called a solution. This is a physical change.
a. Solutions are formed when the starting materials have the physical property of solubility.
b. The starting materials do NOT have reactivity with each other
c. FYI, in this case, the thing being dissolved is called the solute and the thing doing the dissolving in the solvent
3. The materials stay separate. In this case, the substances don’t have the chemical property of reactivity, or the physical property
of solubility.
a. An example of this would be attempting to mix oil and water. They are incompatible and neither mix nor react
Data Table PROPERTIES
Baking Powder
Obs type
Appearance
Texture
Baking Soda
Density
Appearance
Texture
Cornstarch or Flour
Density
Appearance
Texture
Sugar
Density
Appearance
Texture
Density
Change Type
Property
Observations
Data Table CHANGES
Baking Powder
Water
Baking Soda
Observation
Change Type
Property
bubbles
chemical
Reactivity
with
water
Observation
Change Type
Cornstarch or Flour
Property
Observation
Change Type
Sugar
Property
Observation
Iodine
Vinegar
Data Table UNKNOWN
Observations of your unknown?
Unknown _________
Observation
Water
Iodine
Vinegar
Change Type
Unknown ___________
Property
Observation
Change Type
Unknown ___________
Property
Observation
Change Type
Unknown ___________
Property
Observation
Change Type
Property
UNKNOWN LAB
PROCEDURE:
1. Look at each substance & make observations in the “properties” table above.
2. Using a graduated cylinder & large pipet, carefully measure out 2.5ml of water from the plastic
beaker and place into 5 test tubes.
3. Fold a small paper in half and zero it onto the balance. Measure out ~0.1g of baking powder.
Place into the first test tube. “Shake” the test tube using the thumping method. Observe (with
ears & eyes!) what happens. Record.
4. Repeat step 2 with ~0.2g of baking soda in the 2nd test tube. Observe & record.
5. Repeat step 2 with ~0.2g of cornstarch in the 3rd test tube. Observe & record.
6. Repeat step 2 with ~0.2g of sugar in the 4th test tube. Observe & record.
7. Keep the last test tube empty.
8. Add 2 drops of iodine to test tubes 1-5. Thump the test tube to mix. Compare each
mixture/reaction to the 5th test tube. Record in the data table.
9. Send 1 person in your group to rinse each test tube. Everything may go down the sink.
10. Using a small pipet & vinegar, carefully add 1 pipet full of vinegar to 5 test tubes.
11. Fold a small paper in half and zero it onto the balance. Measure out ~0.1g of baking powder.
Place into the first test tube. “Shake” the test tube using the thumping method. Observe (with
ears & eyes!) what happens. Record.
12. Repeat step 2 with ~0.2g of baking soda in the 2nd test tube. Observe & record.
13. Repeat step 2 with ~0.2g of cornstarch in the 3rd test tube. Observe & record.
14. Repeat step 2 with ~0.2g of sugar in the 4th test tube. Observe & record.
15. Keep the last test tube empty.