salt16 Decomposition
of malachite by heat and reduction of the product
In an earlier
experiment
malachite was decomposed resulting in the production of carbon dioxide
and a solution of copper chloride:
Cu2[(OH)2CO3](s) + 4 HCl(aq) --> 2 CuCl2 (aq) +3 H2O(l) + CO2(g)
A. The formula of malachite shows that ist decomposition might result
the formation of CO2(g) and H2O(l):
Cu2[(OH)2CO3](s) --> 2 CuO + H2O(l) + CO2(g)
B. If this is right the reaction beween copper(II)oxide
and methylated spirit (R-H) might result in the formation of copper and
water: CuO(s) + 2 R-H --> 2 Cu (s) + H2O(l) + 2 R
Material
Tray, glass pipette for eye drops with a rubber head, 10 cm silicon tube, small
ampoule, micro
spirit burner
in a stand, tissue paper,
piece of malachite (D 3 mm), methylated spirit ("alcohol"), limewater. Experiment A.
Heat malachite in a glass pipette for eye drops with a rubber head and transfer
gas into
limewater.
B. Pump gaseous methylated spiririt from the rubber head into the
pipette.
1. Transfer a small piece
of tissue paper into the rubber head and add 5 drops of methylated
spirit.
2. Assemble
the apparatus like seen in photo 1.
3. Connect mouth of the pipette with a small tube.
4. Dip its end into an ampoule with 20 drops of limewater.
5. Heat the malachite until the limewater has changed. Remove the tube.
6. Go on heating and press the rubber head to pump alcohol vapour into the pipette.
7. Wait until the copper compound has changed its colour once more,
stop heating.
8. Keep the pipette closed during cooling.
Compare your Observations inside the pipette with those
in photo 2. Write down all your abservationsNotiere deine
