Chemistry in a Ziploc Bag HS
Purpose: Using evidence to identify physical and chemical changes.
Research: Answer the research questions, (you may use the available notes to assist you).
1. What is a physical change? What are the pieces of evidence that indicate a physical change?
2. What is a chemical change? What are the pieces of evidence that indicate a chemical change?
3. What are the physical and chemical properties of Sodium Bicarbonate (NaHCO3 baking soda)?
4. What are the physical and chemical properties of Calcium Chloride (CaCl2)?
5. What is Bromothymol Blue, and what is its purpose in this lab?
Hypothesis: You will be combining all of the chemicals (and water) mentioned in your research questions. Based on
your research, what do you predict will happen when all of the chemicals are combined?
Experiment
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Place 1 spoon of CaCl2 (calcium chloride) in the right corner of a ZipLock bag.
Place 1 of NaHCO3 (baking soda) into a film canister and add 20 mL of water.
Put 20 drops of indicator (Bromothymol Blue) into 20 ml of water and swirl to mix
Pour the water mixture into the Ziploc bag and gently swirl the bag. Make observations.
Carefully, place the film canister with the water and baking soda into the ZipLock bag without spilling any
into the bag.
Carefully push as much air as possible out of the bag and seal the bag.
Tip the film canister over and dump the contents into the bag.
Hold bag away from any faces
Gently swirl the bag, making sure your hands are on the bottom of the bag so that you can feel for any
possible changes.
Record all observations in an organized, easy to read format.
Chemistry in a Ziploc Bag HS
Results
Analysis Questions:
1. Did you observe any physical changes? Explain using your evidence.
2. Did you observe any chemical changes? Explain using your evidence.
3. What piece(s) of evidence that you know can indicate chemical changes was/were not present?
4. How many chemical changed occurred? Describe each.
5. What would happen if CaCl2 was not present in the experiment?