Electrolytic Refining of Copper

Q.

With the help of a diagram explain the method of refining of copper by electrolysis.

Q.

How are broken railway tracks joined? Give the name of the process and the chemical equation of the reaction involved.

Q.

How do alloys brass and bronze differ in composition?

Q.

On electrolysis of dilute copper(II) sulphate solution, copper is deposited at the cathode but hydrogen gas evolves there.

1. False

2. True

Q.

How can copper be extracted from their ore?

Q. During electrolysis metals get deposited at ?

Q.

Brass is an alloy of ________ and ____________.

Q.

When Sodium hydroxide is added to Copper sulphate a pale blue precipitate of Copper hydroxide is obtained. This precipitate can be separated from the mixture by the process of ____________.

Q.

Give the composition of the following alloys.

Brass

Q.

Brass is an alloy of _____ and _____ metals which shows significant ductility.

Q.

Which of the following compound is used as an electrolyte when copper is purified by electrorefining?

1. Copper Sulphate ($CuS{O}_4$)

2. Water ($H_{2}O$)

3. Hydrogen Chloride (HCl)

4. Lithium Bromide (LiBr)

Q.

If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ___________terminal of the battery.

Q.

Give the balanced equation for

(i) A direct combination reaction involving two elements, one of which is a non-metal

(ii) A thermal decomposition reaction involving heat on limestone(calcium carbonate

(iii) An electrolytic decomposition reaction involving neutral liquid

(iv) A displacement reaction involving a metal above hydrogen in the activity series with copper(II) sulphate solution

(v) A double decomposition neutralization reaction involving acid and base

(vi) A white precipitate was obtained during a double decomposition reaction involving a silver salt with sodium salt.

Q.

Solder is an alloy of $\mathrm{Pb}$ and _______?

Q.

State whether the properties of an alloy are similar or different from those of its constituents.

Q.

What type of reaction is involved in the usage of AgBr in photography? The positive print developed is dipped in ${\mathrm{AuCl}}_3$solution at the end to impart beautiful appearance to the photograph. Explain the reaction involved in this. Justify.

Q.

For electroplating of an object with silver, which of the following electrolytes is/are used?

1. $AgN{O}_3$

2. AgCN

3. $CuS{O}_4$

4. NaCl

Q.

On additon of which metal the blue coloured copper sulphate solution turns into colourless solution?

1. $\mathrm{Ag}$

2. $\mathrm{Hg}$

3. $\mathrm{Zn}$

4. $\mathrm{Au}$

Q.

Why do we make alloys? Give two reasons.

Q. What chemical process is used for obtaining a metal from its oxide?

Q. In the process of electrolytic refining, the thickness of cathode increases with time.

1. True

2. False

Q. (I) When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains sulphides of copper (II) and iron (II).
(II) Zone refining is based on the principle that impurities are more soluble in molten metal than in solid metal.
(III) In the metallurgy of aluminium, graphite anode is oxidised to carbon monoxide and carbon dioxide.
Correct statements amongs the following are:

1. I, II
2. II, III
3. I, III
4. all of the above

Q.

What happens when dilute HCl is added to iron fillings? Name the type of reaction involved.

Q. Four faradays of electricity were passed through AgNo3, cadmium sulphate, aluminum sulphate, lead sulphate kept in four vessels using inert electrodes .The ratio of moles of Ag, Cd, Al, Pb deposited will be

Q.

State three reasons, giving suitable examples, why metals are alloyed.

Q. Coke is added during smelting:

1. to reduce FeO to Fe
2. to reduce $C{u}_{2}O$ to $Cu$
3. to check the oxidation of $FeO$ to $F{e}_2{O}_3$
4. to check the oxidation of $C{u}_{2}O$ to $CuO$

Q.

In the extraction of copper from mine, we are now in the roasting phase. Broadly, what will be the components of the product you get for the ore $CuFe{S}_2$ from the reverberatory furnace?

1. Cu₂O

2. Cu₂S

3. FeSiO₃

4. FeS₂

5. FeS (minor) and FeO (major)

Q.

Complete the following reaction:

${\mathrm{KClO}}_3\stackrel{∆}{\to }$

Q. Assertion :Silica is added as a flux in a reverberatory furnace, in the extraction of copper for copper pyrites. Reason: Silica acts as basic flux.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. High purity copper metal is obtained by:

1. carbon reduction
2. hydrogen reduction
3. electrolytic reduction
4. thermite reduction