Getting Copper Fom It So Rev 4

Getting Copper form its ore

Aim

I. To extract copper from the given ore sample.

II. To compare the effectiveness and the cost of different extracting methods.

Introduction (CuCO3‧Cu(OH)2‧H2O)(s) is given as the ore in the extraction. In this experiment, displacement reaction,

carbon reduction and electrolysis are used to extract the copper in the sample.

1. Displacement Reaction

When a more reactive metal is immersed in a less reactive metal ion solution, less reactive metal will

displace on the surface of the more reactive metal. This reaction is called displacement reaction. By

comparing the difference in the mass of the more reactive metal, mass of less reactive metal can be found.

As the sample contains both copper carbonabte and copper hydroxide, 2M sulphuric acid is added to react

with copper carbonate and copper hydroxide to form copper sulphate in aqeuous state.

CuCO3(s)+H2SO4(aq)��CuSO4(aq)+CO2(g)+H2O(l)

Cu(OH)2(S)+H2SO4(aq)��CuSO4(aq)+2H2O(l)

Since zinc is more reactive than copper, it is added into the copper sulphate solution. In order to increase the

rate of reaction, zinc powder is used instead of zinc granules

CuSO4(aq)+Zn(s)��ZnSO4(aq)+Cu(s)

As the copper ion is blue in colour while zinc ion is colourless, the solution changing from blue to colourless

indicates that the displacement reaction has already finished.

2. Carbon Reduction

In carbon reduction, oxygen is removed in order to extract the copper in the sample. The removal of oxygen

is what we called reduction. Carbon is acted as a reducing agent which can remove oxygen. Carbon is

oxidized to carbon dioxide in gaseous state, which can easily escape to the atomsphere. By decantation,

carbon powder adhered on the extracted copper can be removed easily.

(Decantation is that the beaker is swirled so that the heavier copper can fall to the bottom of the beaker)

CuCO3(s)��CuO(s)+CO2(g)

Cu(OH)2(s)��CuO(s)+H2O(l)

2CuO(s)+C(s)��2Cu(s)+CO2(g)

3. Electrolysis

Electrolysis is a method of using an electric current to drive an otherwise non-spontaneous chemical reaction.

It is as a stage in the separation of elements from naturally occurring sources such as ores using an

electrolytic cell, resulting in chemical reactions at the electrodes and the separation of materials.

In the extraction, the ore sample is dissolved in the hydrochloric acid to form copper chloride, which acts as

an electolyte in the electrolysis

CuCO3(s)+HCl(aq)��CuCl2(aq)+CO2(g)+H2O(l)

Cu(OH)2(S)+HCl(aq)��CuCl2(aq)+2H2O(l)

In the electrolysis, copper strip is used as a cathode, while graphite is used as an anode. Copper(II) ion in the

electrolyte will reduce to copper because it is preferentially discharged, while oxygen will evolve at the

graphite electrode. As the concentration of copper(II) ion decreases, the blue colour in the electrolyte will be

fade.

By comparing the difference in the mass of the copper strip cathode and also the graphite anode, mass of

copper extracted can be known.

Material and Apparatus

�Dilute sulphuric acid �Dilute hydrochloric acid

�Zinc powder �Carbon powder

�Copper strip �Graphite electrode

�Deionized water

�Electronic balance �Oven

�Filter paper �Funnel

�Crucible & lid �Tongs

�Glass rod �Beakers

�Spatula �Measuring cylinder

�D.C power supply

Procedure

Displacement reaction

1. Dissolve 2g of ore sample into excess (about 20cm3) into 1M sulphuric acid. Blue copper sulphate

solution is formed

2. Add excess zinc powder in order to displace all the copper(II) ion in the solution. During the reaction,

brown solid will be formed and heat is released.

3. When the solution changes from blue to colourless, add furthter sulphuric acid in order to dissolve all

thr unreacted zinc powder. Hydrogen gas will be given in the reaction.

4. When there is no hydrogen gas evolved, filter the mixture. Use deionized water to wash the copper in

the funnel to prevent the copper from oxidation

5. Put the filtrated copper into an oven at 50°C for drying

6. Measure the mass of the filtrated copper

Carbon reduction

1. Put 2g of ore sample and carbon powder in the crucible. Then, cover the ore layer with another 2g of

carbon pwder (Do not mix the chemical)

2. Put the crucible on a tripod and pipe clay triangle and heat very strongly using Bunsen burner for about

15 minutes.

3. Hold the crucible with tongs and tip the powder from the crucible into a beaker half filled with water.

4. Swirl the beaker, allow the heavier copper to fall to the bottom of the beaker.

5. Pour off the carbon powder and the water.

6. More water can be added to repeat the above decatation process

7. Put the copper extracted into an oven at 50°C for drying

8. Measure the mass of the copper

Decantation

Electrolysis

1. Dissolve 2g of the ore sample completely in 90 cm3 of 1M hydrochloric acid to obtain copper chloride

solution. Use the solution as electrolyte

2. Weigh the copper strip and use it as cathode, while use graphit electrode as anode

3. Carry out electrolysis as show in the setup below for about an hour

4. after an hour, filtrate the electrolyte in order to separate the reduced copper and the solution

Precaution

�Put the extracted copper into water to prevent them from oxidation

�Temperature of oven should not be too high or too low

- Copper extracted will re-oxidize

�Prevent the extracted copper to be dried overtime or else the copper will oxidize

Results

1. Displacement reaction

Set Mass of sample Mass of zinc Mass of copper

oxide

Mass of copper

extracted*

A 1.98g 3.04g 1.63g 1.29g

B 1.99g 3.03g 1.61g 1.30g

C 1.98g 3.05g 1.62g 1.29g

Average 1.98g 3.04g 1.62g 1.29g

* As Cu will oxidze to CuO readily in the displacement reaction

- 2Cu(s)+O2(g)�2CuO(s)

Mass of CuO is actually weighted. In order to caluclate the approximate value of copper extracted, mole of

CuO is found. As mole of CuO equals to that of Cu, mass of Cu can be found.

2. Carbon reduction

Set Mass of sample Mass of copper extracted

A 2.01g 1.25g

B 2.00g 1.23g

C 1.98g 1.29g

Average 2.00g 1.26g

3. Electrolysis

Set Mass of sample Current Mass of copper

electrode

Mass of copper in

electrolyte

(Residue in filter paper)

(Total mass - mass of

filter paper)

A 1.02g 0.4A 1.39-1.25=0.14g 1.23-0.74=0.49g

B 1.02g 0.3A 1.4-1.27=0.13g 1.98-0.75x2=0.48g

C 1.02g 0.3A 1.39-1.26=0.13g 1.25-0.74=0.51g

Average 1.02g 0.3A 0.13g 0.49g

Data analysis


A B C Average Cost

Percentage by mass of

copper in the sample

65.15% 65.33% 65.15% 65.21% $0.3

(mass of copper

extracted/mass of

copper

extracted)x100%

Volume of 2M H2SO4(aq) used = 20cm3

Mass of Zinc:

Zn(s) + CuSO4(aq) � Cu(s) + ZnSO4(aq)

1.29g

No. of mole of Cu = 1.29/63.5 = 0.020mol

No. of mole of Zn used = 0.020mol

Mass of Zn used= 0.020×65.4 = 1.33g

Cost = Cost (H2SO4) + Cost (Zinc)

= (0.02dm3/1dm3)($4) + (1.33g/100g)($17)

= $0.08 + $0.226

= $0.305861732

= $0.3 (1 d.p.)

2. Carbon reduction

A B C Average Cost



(mass of copper

extracted/mass of

copper

extracted)x100%

62.19% 61.50% 65.15% 62.95% $1.6

Average mass of carbon powder used = 1.50g

Time used = 15 minutes

Cost = Cost (Carbon powder) + Cost (Bunsen burner)

= (1.5g/100g)($12) + (1.33×103J/106J)(15min×60s)($0.21)

= 0.18 + 1.407

= $1.587

=$ 1.6 (1 d.p.)

3. Electrolysis

A B C Average Cost



(mass of copper

extracted/mass of

copper

extracted)x100%

61.76% 59.80% 62.75% 61.44% $0.4

Time used = 1 hour

Volume of 1M HCl(aq) used = 90cm3

Power = Current × Voltage = 0.3A × 12V = 3.6W

Cost = Cost (Electrolysis) + Cost (HCl)

= ($1.265)(3.6W/103W) + ($4.8)(0.09dm3/1 dm3)

= $0.436554

= $0.4 (1 d.p.)

Error and Limitation


�Excess zinc may not be totally removed from the solution

� Oxidation of copper cannot be prevented whenever the extracted copper is exposed into air (i.e. copper is

re-oxidized)(e.g. When the copper is transferred to the oven, copper extracted will exposed into air,etc),

- Copper is oxidized to copper oxide, which causes the mass of the extracted copper to increase

�Zinc powder may contain impurities, which cannot be removed only by sulphuric acid

- It causes the mass of the copper measured to increase

2. Carbon reduction

�In decantation, copper extracted can not be totally separated from the carbon powder

- Centrifuge is used. However, the upper layer and the lower layer are too close, which cannot be

separated by a easy method

- It causes the mass of copper measured to increase

�Oxidation of copper cannot be prevented whenever the extracted copper is exposed into air (i.e. copper is

re-oxidized) (e.g. When the copper is transferred to the oven, copper extracted will exposed into air,etc)

- Copper is oxidized to copper oxide, which causes the mass of the extracted copper to increase

3. Electrolysis

�Copper cannot be totally extracted from the copper chloride solution(Electrolyte is still blue in colour)

�Carbon cannot be totally separated from the electrolyte

- During the electrolysis, graphite electrode will decompose. Carbon powder will not adhere on the

graphite electrode but it will fall to the bottom of the beaker or simply adhere on the extracted copper.

- It causes the mass of copper measured to increase

Improvement


�Filter the solution several times.

�Immerse the extracted copper into water when it is being transferred to the oven,

take the copper out and put it on a evaporating dish inside the oven.

- reduce the time of copper exposing into air

2. Carbon reduction

�Increase the amount of extracted copper by increasing the amount of ore used

- The significance of the amount of carbon powder on the surface of the extracted copper is reduced

�Immerse the extracted copper into water when it is being transferred to the oven,

take the copper out and put it on a evaporating dish inside the oven.

- reduce the time of copper exposing into air

3. Electrolysis

�Use platinum electrode instead of graphite electrode.

- No carbon powder will fall off into electrolyte

�If graphite electrode is used

- Find the mass difference(D) of graphite electrode before and after the experiment. Carbon powder

in the electrolyte can be found out

- Mass of copper extracted= Mass of carbon and copper in the electrolyte-mass difference of graphite

electrode(D)

Conculsion

Comparision

Displacement reaction Carbon reduction Electrolysis

Percentage of extraction 65.21% 62.95% 61.44%

Cost $0.3 $1.6 $0.4

From the above table,

�Effectiveness

Displacement reaction is the most effective extracting method, followed by carbon reduction, electrolysis is

the less effective extracting method.

�Cost

Carbon reduction is the most expensive method, followed by electrolysis, ddisplacement reaction is the

cheapest among three methods

Members:

Chan Mong Ki Charis

Li sze Ni

Wong Tsz Kwan

Yuen Wai Man

Getting Copper Fom It So Rev 4

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