Refining of Metals

Q.

The process of zone refining is used in the purification of

1. Si

2. Al

3. Ag

4. Cu

Q.

What is recrystallization?

Q.

How is the method of extraction of metals, high up in the reactivity series different from that for metals in the middle? Why cannot the same process be applied to them? Name and explain the process of extraction of sodium.

Q.

During the extraction of metals, electrolytic refining is used to obtain pure metals.

(a) Which material will be used as anode and cathode for refining silver metal in this process?

(b) Suggest a suitable electrolyte also.

(c) In this electrolytic cell, where do we get pure silver after passing an electric current?

Q. How electrolysis can be used in extraction of aluminium? Why aluminium cannot be reduced by conventional reducing agents?

Q.

Which process is used to reduce aluminium oxide to aluminium?

1. Hydraulic washing

2. Roasting

3. Electrolytic reduction

4. Thermit process

Q.

Which of the following is a ferrous alloy?

1. Brass

2. Magnalium

3. Steel

4. Solder

Q.

Briefly explain any three methods for the refining of metals.

Q.

State three industrial applications or uses of electrolysis.

Q. Explain, why electrolysis is an example of redox reaction?

Q.

Volatile metals are purified by:

1. Electrolytic refining

2. Liquation

3. Oxidation

4. Distillation

Q. During electrolytic refining of copper, the anode is made up of

1. pure copper, metal
2. impure copper metal
3. graphite
4. platinum

Q. The following questions relate to the extraction of aluminium by electrolysis.
(a) Give the equation for the reaction which takes place at the cathode.
(b) Explain, why it is necessary to renew the anode periodically.

Q. The mixture involved in the extraction of iron by thermite reaction is:

1. a mixture of $\text{Mg}$ and ${\text{BaO}}_2$.
2. a mixture of ${\text{Fe}}_2{\text{O}}_3$ and aluminium powder.
3. a mixture of ${\text{Al}}_2{\text{O}}_3$ and iron.
4. a mixture of $\text{Al}$ and ${\text{MnO}}_2$.

Q.

Name the following

Two metals are obtained by the process of electrolysis of their fused chlorides.

Q. Smelting is the process of separating any metal from another pure form of a metal.

1. True
2. False

Q.

The process of zone refining is used in the purification of

1. Si
2. Al
3. Ag
4. Cu

Q.

State two industrial uses of electrolysis

Q. Write the principle of distillation.

Q. In stainless steel, iron is mixed with

1. Ni and Cr
2. Cu and Cr
3. Ni and Cu
4. Cu and Au

Q.

Which of the following is most economically refined by fractional distillation?

1. $\mathrm{Zn}$

2. $\mathrm{Ni}$

3. $\mathrm{Cu}$

4. $\mathrm{Fe}$

Q.

Which of the following salt solution is used as an electrolyte in the electrolytic refining of copper metal?

1. Copper sulphate

2. Zinc sulphate

3. Sodium chloride

4. Copper metal

Q.

State your observations

Why an aqueous solution of Sodium chloride conducts electricity?

Q. Aqueous solution of sodium chloride conducts electricity due to the presence of free . [1 mark]
A. electrons
B. ions
C. molecules
D. atoms

Q. During the electrolysis of copper [II] sulphate solution using platinum as cathode & carbon as anode. State the change noticed in the electrolyte.

1. Blue colour remain
2. Blue colour change to red
3. Blue colour disappear
4. None of these

Q.

The given figure is the experimental setup to refine copper metal. Answer the following question:

In which direction do ${\mathrm{Cu}}^{2+}$ion move in electrolytic cell.

Q. Match the alloys with their constituent elements.

1. Copper and tin
2. Zinc and copper
3. Iron and carbon

Q.

During the process of electrolytic refining, the pure metal is deposited at the ________.

1. anode
2. cathode
3. bottom of the solution
4. initially at cathode and then at anode

Q. _______ is an alloy of copper and tin.

1. Gold
2. Steel
3. Bronze
4. Brass

Q. ___ is a method in which a low melting metal like the tin can be made to flow on a sloped surface to separate it from high melting impurities.