CONSERVATION OF MASS LAB
Pre-lab Questions
1. Define the law of conservation of mass.
2. If 30g of sodium reacts with 20g of chlorine to create sodium
chloride, how much sodium chloride should be produced?
Purpose: To observe mass being conserved during a chemical
reaction.
Hypothesis:
Materials: Erlenmeyer flask, graduated cylinder, alka seltzer
tablet, balloon, electronic balance, scoopula
Procedure:
1. Obtain a clean Erlenmeyer flask and a new balloon.
2. Measure 50 mL of water into the flask.
3. Take the tablet and put it in the balloon.
4. Place the balloon over the opening of the flask without the
tablet falling into the flask.
5. Mass the apparatus and record the mass.
6. After recording the mass, lift the balloon and dump the
tablet into the water.
7. Swirl the flask to complete the reaction.
8. Do not remove the balloon!!!!!!!!!!
9. Take the mass of the apparatus again. Record the mass.
10. Finally remove the balloon.
11. Take one final mass of the flask with its contents and the
balloon lying off to the side.
Data:
Mass of the Balloon and Flask Apparatus
After the balloon is
Before the reaction
After the reaction
removed
Conclusion Questions:
1. Compare the masses of the apparatus before and after the
reaction. How do they compare?
2. Why did the balloon expand?
3. Did the substance in the balloon have mass? Explain.
4. How does the mass of the apparatus after the balloon has
been removed compare to the mass of the apparatus after
the reaction? Explain any discrepancies in your data.