CHM 130
Analysis of Copper Ore for Cu Content
Introduction:
Copper, in various forms, has been mined from the Earth ever since mankind started using metal tools.
Early Egyptian civilizations used bronze, an alloy of copper and tin, to make tools, weapons, and
jewelry. Surface ore supplies were used up quickly and deeper ore deposits needed to be mined in order
to access additional copper ores. Today, rich copper deposits are rare and deposits of native copper
(pure copper metal) are very scarce. Most ores mined today are made of compounds that contain less
than 1% copper.
Mining the ore out of the ground is not complicated, but extracting the copper metal from the ore can be.
Most ores are compounds of sulfides, carbonates, or silicates, and the metals can be extracted using the
chemical properties of these compounds. Most copper ores are carbonates and so the chemical reaction
of carbonates and acid can be used to dissolve the ore. Once the ore is dissolved, then the copper can be
removed from the solution using a more active metal or by passing electricity through the solution.
Many reactions are accompanied by an energy change. Energy can take the form of heat or light. If a
reaction releases thermal energy it is called exothermic. Exothermic reactions cause their surroundings
to feel warm to the touch. The thermal energy released by the reaction is absorbed by the surroundings
(water, beaker, etc) and the temperature goes up. If a reaction absorbs thermal energy it is called
endothermic. Endothermic reactions cause their surroundings to feel cold to the touch. The thermal
energy absorbed by the reaction is taken from the surroundings (water, beaker, etc) and the temperature
goes down.
In this lab you will use aluminum, a more active metal than copper, to precipitate copper metal from
solution.
unbalanced equation: Al (s) + CuCl2 (aq) → AlCl3 (aq) + Cu (s)
You will analyze the amount of copper extracted from two different types of copper ore, azurite and
malachite. From the data you collect you will be able to determine the weight percent of copper in each
of the ores.
Objectives:
Use a series of chemical reactions to determine the percentage of copper in two common forms of
copper ore, malachite and azurite.
Experimental:
Coordinate with another team in the lab room. Each of the two teams should take a sample of one
of the ores so that one team has malachite and the other has azurite. Each team then completes steps
2 – 13 for their ore sample. The two teams will be sharing observations and data for their respective
ore sample.
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Each team will do the following with their ore:
1. Take a piece of the ore (malachite or azurite) and find the mass; try to get some mass under 1 gram.
Record the mass of your ore on the data table.
2. Grind the ore using the mortar and pestle so that it is a fine powder.
3. In the fume hood, add ~10 mL of 3M HCl to the mortar. Use the acid to rinse off any ore from the pestle.
Watch what happens in the mortar! Allow the reaction to continue until it stops. Compare your reaction
to the group using the alternate ore. Record your observations about the color of the solution in the data
table.
4. Using a piece of filter paper, a glass funnel, and a 125 mL Erlenmeyer flask, filter the solid from the
liquid in the mortar, and wash off the mortar with DI water until all the material has been removed from
the mortar, and washed off into the filter paper. Keep the liquid, place the filter paper and solid into a
waste container.
5. Set a large test tube into a clean 250mL Erlenmeyer flask, and transfer the filtrate (the liquid you filtered
in step #4) into the large test tube.
6. Obtain a length of Aluminum wire, about 20-25cm long; each team should have the same length of wire.
Wrap the Al wire around a pencil, so that it resembles a coil, but leave one end straight. Hold the straight
end of the wire and lower the coil into the test tube with the filtrate from step #5. Watch as the reaction
occurs, and compare both ores simultaneously.
7. Every 1-2 minutes, gently shake the wire up and down to remove the residue. Wait for the reaction to
finish completely, this should take 10-15 minutes.
a. Pick up the test tube and feel the outside, record your observation about the temperature change of
the reaction in the data table.
b. Observe the color change that is occurring in the solution during the reaction. Record your
observations in the data table.
c. Watch both teams’ results so that a comparison can be made between each ore as to the time for the
reaction to complete, as well as any other differences that can be observed.
8. When the reaction is complete, gently shake the wire and remove it from the test tube. Use the wash
bottle of DI water to remove as much residue sticking to the wire as possible, and get this residue into the
test tube. Once the wire is clean, you may throw it away.
9. Obtain another piece of filter paper. Write your group’s name on the filter paper.
Then weigh it and record the mass on the data table.
10. Carefully filter the solid in the test tube using the glass funnel, use the wash bottle to ensure that you get
all of the solid into the filter paper.
a. Rinse the solid and filter paper again with DI water to remove as much excess solution as possible.
b. Rinse the solid and filter paper with acetone. This will remove some water and help the solid to dry
faster.
11. Carefully remove the filter paper from the glass funnel (wet filter paper is very fragile and tears easily),
fold it in half and place it on a watch glass.
12. Place the watch glass into the drying oven.
13. When the filter paper is dry, weigh it and record the mass.
Clean Up
Dispose of all chemicals in the appropriate waste containers including the dried copper and filter paper
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Name _______________________ Section ______
Lab Partner __________________
Analysis of Copper Ore for Cu Content
A. Data Table
Your Ore Sample
The Other Team’s Ore Sample
Identity of the Ore
Mass of ore used, grams
Observations after adding
HCl to the ore.



Describe what you
see happening.
What color is the
solution?
What is creating the
observed color?
Should be bubbling/fizzing
Solution will be green or bluegreen
Copper ions dissolved in solution
are creating the color
Length of Al wire used.
Observations after adding
the Al wire.



Describe what you
see happening.
What is the
temperature of the
test tube?
Why is the solution
changing color?
Bubbling/ fizzing
Brown crystals growing on Al
wire
Solution changing color from blue
to grey/white/clear
Copper ions leaving the solution
and turning into solid copper
metal
Mass of filter paper, grams
Mass of filter paper plus
copper after drying, grams
Mass of copper, grams
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Results Table:
Your Ore Sample
Other Team’s Ore Sample
Mass of ore sample, grams
Mass of copper after drying,
grams
% of Cu in ore
Results:
1.
Identify your ore sample as either malachite or azurite.
2. Calculate the mass percent of Copper in your ore sample, using the idea that % = (part/total) x 100.
3.
Calculate the mass percent of Copper in the other team’s ore sample.
4. Compare the % copper in your ore to the group who had the different ore. Which ore had the most
copper in it?
The azurite should have more copper than the malachite
5. Which ore would you use if you were in the business of mining copper, and why?
Azurite would be more profitable. You get more copper from the same amount of ore.
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6.
Why did you use HCl in step #3?
To dissolve the ore. The ore is a carbonate compound and it will react with HCl, dissolving
the copper into ions in solution.
7.
In step #7, what was going on chemically…what type of reaction was this? (examples:
combination, decomposition, single replacement, double replacement, acid-base, combustion)
Include a balanced chemical equation.
Type of reaction: _ single replacement _
Balanced Equation:
2 Al (s) + 3 CuCl2 (aq) → 2AlCl3 (aq) + 3 Cu (s)
Complete Ionic Equation:
2 Al (s) + 3 Cu2+ (aq) + 6 Cl- (aq) → 2Al3+ (aq) + 6 Cl- (aq) + 3 Cu (s)
Net Ionic Equation:
2 Al (s) + 3 Cu2+ (aq) → 2Al3+ (aq) + 3 Cu (s)
8. In step #7, there was a second reaction occurring between the Al wire and the excess HCl, that
created a gas (bubbles). Write a balanced chemical equation for this reaction.
_ 2 _Al (s) + _ 6 _ HCl (aq) → _ 2 _ _ AlCl3 _ (aq) + _ 3 _ _ H2 _ (g)
9. Was this reaction (in step #7) exothermic or endothermic and how did you know? (Compare the
observations from both groups.)
Exothermic. The outside of the test tube was warm. The malachite gives off much less heat
than the azurite.
10. How did the color of the solution you were working with at different times indicate what was
going on chemically?
Color of the solution after adding HCl:_ the solution turned green or blue-green _
What is in the solution that is creating this color?
dissolved copper ions
Color change in the solution after adding the Al wire: _ blue _ to _ grey/white/clear _
What is in the solution that is creating this color change?
Copper ions removed from solution
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