Grade 9 Academic Science – Chemistry
Mass and Proportion
Name: ___________________________
The Law of Conservation of Mass states that “the mass of the products must equal the mass of
the reactants”. In previous experiments, we have demonstrated this principle.
We can also use this principle to measure the mass of the new product formed during the
chemical reaction. In this laboratory, we will measure the mass “lost” when copper II carbonate
hydroxide (Cu2CO3(OH)2) decomposes in air. To do so, we must capture all of the solid products
remaining after the chemical reaction is complete.
Types of Chemical Reaction
We have studied four types of chemical reactions:
 Synthesis
 Decomposition
 Single Displacement
 Double Displacement
When Cu2CO3(OH)2 is heated strongly in air, the type of reaction that occurs is
______________________.
Why is the chemical formula Cu2CO3(OH)2? Hint: Ionic Charge for each ion is Cu2+, CO32- and
OH1-. What is the “total charge” for the total of each ion in the formula? Hmmmmm…
When heated, Cu2CO3(OH)2 separates into a solid (copper II oxide) and two gases (CO 2(g) and
H2O(g)). Write the balanced chemical formula for this reaction
_____________________
_______________ + _____________ + _____________
Since two products are gas, predict the mass of the measurable products. Will it be more or less
than the mass of the reactants?
Materials
 Cu2CO3(OH)2
 Bunsen burner
 Scoopula
 Test tube
 Test tube holder
 Test tube cleaning brush
 Striker
 Tongs
 Electronic Balance
 Beaker
 Wood splint
Methods
1. Obtain a test tube and clean it with water and the brush
2. Dry the test tube by mildly heating it over a Bunsen burner. Let the test tube cool
3. Using the electronic balance, measure and record the mass of the empty test tube
4. Using the scoopula, obtain a small mass of Cu2CO3(OH)2. Make sure the chemical is in
the bottom of the test tube.
5. Using the electronic balance, measure and record the mass of the test tube and
Cu2CO3(OH)2
6. Subtract the mass of the empty test tube to determine the mass of the Cu2CO3(OH)2.
Record the mass
7. Place the test tube in a holder and heat using medium strong flame over the Bunsen
burner until the reaction is complete. How do you know a chemical reaction has
occurred? Provide TWO OBSERVATIONS
8. Using the wood splint, test for a gas. Light the splint using the Bunsen burner and insert
it into the mouth of the test tube. Record observations.
9. Allow the test tube to cool by placing it in a beaker using the tongs.
10. Using tongs, carefully move the test tube to the electronic scale and measure the mass of
the test tube and the solid product of the reaction. Record the information
11. Calculate and record the mass of the solid product
12. Calculate the mass of the gases “lost”
13. Calculate and record the ratio of mass solid product to mass reactant. The formula is
Ratio = mass(Product) / mass(Reactant)
14. Collect data from other groups
15. From the group data, what are your observations?
16. Write a lab report about Conservation of Mass from your experimental findings.
Table 1. My Initial Data
1
Mass of empty test tube (g)
2
Mass of test tube and Cu2CO3(OH)2 (g)
3 (2-1)
4
5 (4-1)
Mass of Cu2CO3(OH)2 (g)
Mass of test tube and CuO (g)
Mass of CuO (g)
6
Mass of gases produced and “lost) (g)
7
Ratio mass(Product) : mass(Reactant)
Table 2. Group Data
Group
Mass of Cu2CO3(OH)2
(g)
Mass of CuO
(g)
Ratio
mass(Product) : mass(Reactant)
1
2
3
4
5
6
7
From your observations, can you see any source of error in the experiment design?