zD7 _LAB - Decomposition of Malachite_

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					           Lab: Thermal Decomposition of Malachite
Malachite is a mineral with the formula Cu2CO3(OH)2(s). When heated, malachite
decomposes to produce copper(II) oxide, carbon dioxide and water vapour.

QUESTION:
What is the relationship between the mass of the malachite that is decomposed and the
mass of the copper(II) oxide that is produced?


MATERIALS:
 malachite                       clay triangle                    retort stand
 crucible                        Bunsen burner                    electronic balance
 iron ring


PROCEDURE:
1. Read the entire procedure and construct a data table to record your observations.
2. Carefully weigh a dry empty crucible. Place 2 to 4 g of malachite in the crucible and
   reweigh it. Record the weight of the empty crucible and the weight of the crucible
   containing the malachite.
3. Set the crucible on a clay triangle supported by an iron ring attached to a retort stand.
   Heat with a Bunsen burner for 10 minutes. Be sure that the crucible is in the flame of
   the burner.
4. Allow the crucible and contents to cool to room temperature. Reweigh the crucible
   containing the product, CuO(s), and record your data.


OBSERVATIONS:

                                                 Mass of
                                 Mass of                            Mass of       Mass of
                 Mass of                        Crucible +
                                Crucible +                         Malachite     Copper(II)
   Group         Crucible                       Copper(II)
                                Malachite                          Reacted         Oxide
                   (g)                            Oxide
                                   (g)                               (g)            (g)
                                                   (g)
      1
      2
      3
      4
      5
      6
      7
ANALYSIS:

1. Write a balanced chemical equation for the thermal decomposition of malachite.

2. Graph the class results with a line graph comparing the mass of the malachite reacted
   (independent variable, x-axis) to the mass of the copper(II) oxide produced
   (dependent variable, y-axis).

3. Calculate the slope of your line of best fit.

4. Use your graph to predict the mass of copper(II) oxide produced if 120 g of malachite
   had reacted.

5. Use your graph to predict the mass of malachite reacted if 300 g of copper(II) oxide
   had been produced.

				
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posted:12/22/2011
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