Conservation of Matter
DO NOT WRITE ON THIS LAB
Purpose: To prove that matter is neither created nor destroyed, it just changes form.
Hypothesis:
Which system will show the smallest change in mass? (Open or Closed) WHY?
Materials:
Graduated Cylinder
baking soda (NaHCO3)
1 cup
balance
vinegar (CH3COOH)
twist ties
paper
Straw/spoon
plastic bag
Procedure:
Part 1: Open System
1. Mass the cup
2. Measure 50 ml of vinegar
3. Mass 50 ml of vinegar in cup
4. Mass a piece of paper
5. Mass 2 g of baking soda on paper
6. Add mass of only vinegar and only baking soda to find initial mass
(Mi).
7. SLOWLY pour baking soda into cup. (Any temp. change?)
8. Let solution sit until all chem. rxns. are completed.
9. Mass cup and products.
10. Subtract mass of cup to get final mass (Mf).
11. Calculate change in mass by subtracting final mass from initial
mass.
Part 2: Closed System
1. Mass piece of paper.
2. Measure 2g of baking soda.
3. Place soda into corner of baggie, use twist tie to tie corner.
4. Measure 50 ml vinegar using grad. cylinder.
5. Carefully pour vinegar into opposite corner of baggie.
6. Seal baggie top.
7. Measure mass of baggie with vinegar and baking soda with the
twist tie still on. (Mi)
8. Undo twist tie and mix compounds together. (Any temp. change?)
9. After chemical rxn. is complete, mass baggie, twisties and
contents.
Results:
Table 1:
Initial Mass (Mi)
Part 1 (Open System)
Part 2 (Closed System)
Calculations:
Change in Mass = Mf - Mi
Final Mass (Mf)
Change in Mass (M)
Analysis questions:
1. What causes bubbles in the reaction?
2. Write the reactant side (left side of arrow) of the chemical formula for the reaction
between baking soda and vinegar.
3. What gas do you think the bubbles are?
4. Did the temperature of the bag increase or decrease?
5. Did the mass change more in the open or closed system? WHY?
6. Did the open system follow the conservation of matter even though it may have
lost some mass?
Conclusion: (5 step conclusion)
1. Restate purpose
2. Accept or reject hypothesis
3. Applications
4. What you learned
5. Errors