1. Go to your next open page and put the title and date on it.
REACTING to Density
Go to your next open page and put the title and date on it.

2. Materials Gathering data Empty plastic water bottle
1 antacid tablet – each table has a packet of 2 tablets
25 mL water
Bottle cap OR balloon
Scale
Graduated cylinder
Pipette
Two pairs are sharing the scale.
One pair will be doing this experiment using a bottle cap, the other will be using the balloon.
Both pairs must have sketches and data for both reactions.
Because you are gathering data and sketches for two reactions it might be useful to draw a line down the middle of you page

3. Overview of Lab
You will be using a plastic bottle to see what happens during a chemical reaction between antacid tablets and water.
The reaction is a closed system once the cap or balloon goes on nothing can get in or get out.
Each person will have before and after sketches of each set-up (one with a balloon and one with a bottle cap).
Each person needs to have the 3 sets of masses for both set-ups: before the reaction; after the reaction and after the removal of the cap / balloon

4. Procedure—each pair will be doing the same thing with their own set up.
Measure 25mL of water, use the pipette to add or remove the last milliliter or so
Pour the water into the bottle
All of the following items go on the scale at the same time to be massed:
bottle with 25mL of water
1 antacid tablet
Bottle cap OR balloon (depending on which you are doing)
Record the mass of the set up before the reaction

5. 4. Before Reaction Sketches
Before Reaction Sketch—bottle cap
Before Reaction Sketch--balloon
antacid
Label all parts of the set-up: bottle, water, cap, etc.
antacid

6. Reaction
Once your set up has been sketched one person break the tablet in half.
The other person has the cap or balloon ready to put onto the bottle after the first person drops the tablet into the bottle.
The first person drops the tablet in the bottle and the second person quickly puts on the cap or balloon.
Allow the reaction to proceed—make observations of what is happening. How do you know the reaction is occurring? How will you know it is done?
To ensure that the reaction has totally finished, shake the bottle a couple of times— leave the cap or balloon on until told to take off.

7. After Reaction Mass & Sketches
Bottle Cap Sketch
Balloon Sketch
Mass the entire set up after the reaction finished. Record final mass.
Make a sketch of your bottle after the reaction. Don’t take the cap off.
Observe the bottle—you started with a slightly crumpled bottle, is it still?
Mass the entire set up after the reaction finished. Record final mass.
Make a sketch of your bottle after the reaction. Don’t take the balloon off.
Observe the bottle—you started with a slightly crumpled bottle, is it still?

8. Take Off the Cap or Balloon
Observations--cap
Observations—balloon
What did you see or hear as the cap came off?
Mass the set-up again, include the cap on the scale but don’t have it on the bottle.
Record final mass. You now have three masses: before reaction, after reaction, after removing cap.
What did you see or hear as the balloon came off?
Mass the set-up again, include the cap on the scale but don’t have it on the bottle.
Record final mass. You now have three masses: before reaction, after reaction, after removing cap.
Remember you need data from the other pair!

9. Clean Up
Dump the liquid out of your bottle (into one of the two tubs in the room).
Rinse the bottles with a bit of water and shake out as much water as you can.
Return the materials to your table, ensure that the bottle cap is with the bottle.
Put the balloons in the container provided for them.
Clean up around your station. Be sure that each table is dry and has 2 bottles, 1 cap, 1 scale, 1 50mL graduated cylinder, 2 cups with water

10. Post Lab Questions copy and answer OR restate the question in the answer
Compare your before and after reaction masses, are they the same or nearly the same? As long as they are within 0.5g they are nearly the same.
What was the difference in mass from after reaction to final mass?
Did you see or hear anything escape from the bottle?
What phase of matter was whatever that escaped?
Is the substance that escaped matter? How do you know?
What do you think the substance that escaped was?