Electrolytic Refining

Q. When $CuS{O}_4$ is electrolysed using platinum electrodes:

1. Copper is liberated at cathode, sulphur at anode
2. Copper is liberated at cathode, oxygen at anode
3. Sulphur is liberated at cathode, oxygen at anode
4. Oxygen is liberated at cathode, copper at anode

Q. Why is anode negatively charged and why does oxidation takes place in it?

Q. During the process of electrolytic refining of copper, some metals present as impurity settle as 'anode mud'. These are:
[1 Mark]

1. Fe and Ni
2. Ag and Au
3. Pb and Zn
4. Sn and Ag

Q. The process where the anode is an impure metal and the cathode is a pure metal used in refining is called ___

Q. The product obtained from the electrolytic oxidation of acidified sulphate solution , is

1. $HS{O}_4^{-}$
2. $H{O}_{3}SOS{O}_{3}H$
3. $H{O}_{2}SOS{O}_{2}H$
4. $H{O}_{3}SOOS{O}_{3}H$

Q.

In electrolytic refining, the impure metal acts as anode.

1. True

2. False

Q.

Name the common elements presents in the anode mud in electrolytic refining of copper. Why are they so present?

Q.

Out line the principles of refining metals by the following method:

Zone refining

Electrolytic refining

Vapour phase refining

Q. 29. Which method can be used to distinguish [Co(NH3)6] [Cr(NO2)6] and [Cr(NH3)6] [Co(NO2)6] a. by measurement of their conductivity b. by titration method c. by percipitation method with AgNO3 d. by electrolysis of their aqueos solution

Q. Which among the following equations represents the reduction reaction taking place in lead accumulator at positive electrode, while it is being used as a source of electrical energy?

1. $PbS{O}_4\left(s\right)+2H_{2}O\left(l\right)\to Pb{O}_2\left(s\right)+S{O}_4^{2-}+4H^{+}+2e^{-}$

2. $PbS{O}_4\left(s\right)+2e^{-}\to Pb\left(s\right)+S{O}_4^{2-}\left(aq\right)$

3. $Pb\left(s\right)+S{O}_4^{2-}\left(aq\right)\to PbS{O}_4\left(s\right)+2e^{-}$

4. $Pb{O}_2\left(s\right)+S{O}_4^{2-}\left(aq\right)+4H^{+}\left(aq\right)+2e^{-}\to PbS{O}_4\left(s\right)+2H_{2}O\left(l\right)$

Q. how does mercury cell becomes dead if its electrolyte is not being used up in any reaction

Q. why sodium metal is not obtained at cathode when aq NaCl is electrolysed with Pt electrodes but obtained when molten NaCl is electrolysed.

Q. When a dilute aqueous solution of lithium chloride is electrolysed using graphite electrodes, which of the following is/are true?

1. $H_2$ is liberated at the cathode
2. $C{l}_2$ is liberated at the anode
3. $Li$ is deposited at the cathode
4. $O_2$ is liberated at the anode

Q.

Impure metal rod is to be purified using electrolysis. Which of the following is correct?

1. Impure metal rod is made anode

2. Impure metal rod is made cathode

3. Molten impure metal serves as electrolyte

4. Impure metal rod is made cathode and anode both

Q.

Outline the principles of refining of metals by the following methods:

(i) Zone refining

(ii) Electrolytic refining

(iii) Vapour phase refining

Q. Copper is purified by the electrolytic refining of blister copper. The correct statement(s) about this process is/are:

1. impure Cu strip is used as cathode
2. acidified aqueous $CuS{O}_4$is used as electrolyte
3. pure $Cu$ deposits at cathode
4. impurities settle as anode mud

Q. In the electrolytic refining of copper using $CuS{O}_4$ as the electrolyte, the anode reaction is

1. $4O{H}^{-}\left(aq\right)\to O_2\left(g\right)+2H_{2}O\left(l\right)+4e^{-}$
2. $C{u}^{2+}\left(aq\right)+2e^{-}\to Cu\left(s\right)$
3. $2S{O}_4^{2-}\left(aq\right)\to S_2{O}_8^{2-}\left(aq\right)+2e^{-}$
4. $Cu\left(s\right)\to C{u}^{2+}\left(aq\right)+2e^{-}$

Q. What is electrochemistry?

Q.

In the electrolytic refining of Copper (electrolyte is $CuS{O}_4$ solution + dil $H_{2}S{O}_4$ _;Pure Cu cathode and Impure Cu anode), metallic impurities having lower oxidation potential than Cu are deposited as __ sludge.

Q. Copper is purified by the electrolytic refining of blister copper. The correct statement(s) about this process is/are:

1. impure Cu strip is used as cathode
2. acidified aqueous $CuS{O}_4$is used as electrolyte
3. pure $Cu$ deposits at cathode
4. impurities settle as anode mud

Q. When copper metal is refined by electrolytic method, incorrect statement is

1. Anode is made of impure metal while pure metal is cathode
2. $CuS{O}_4$ can be used as electrolyte
3. During electrolysis impurities collected as anode mud
4. Anode is made of pure metal while cathode is made of impure metal

Q. Purification of aluminium by electrolytic refining, is known as ____________.

1. Baeyer's process
2. Serpeck's process
3. Hall's process
4. Hoope's process

Q. Electrolytic reduction of alumina to aluminium by Hall-Heroult's process is carried out____.

1. in the presence of sodium chloride
2. in the presence of flourite
3. in the presence of cryolite which forms a melt with lower melting temperature
4. in the presence of cryolite which forms a melt with higher melting temperature

Q.

In the electrolytic refining of Copper (electrolyte is $CuS{O}_4$ solution + dil $H_{2}S{O}_4$ _;Pure Cu cathode and Impure Cu anode), metallic impurities having lower oxidation potential than Cu are deposited as __ sludge.

Q. ${AgNO}_3$ solution can be stored in a metal container.

1. True
2. False

Q. Write two applications of electrochemical series?

Q. Which of the following is true for electrolytic cell?

1. Spontaneous reaction will occur
2. Non-spontaneous reaction will occur
3. Electrons flow is opposite to galvanic cell
4. Electrons flow is same as galvanic cell

Q. For the electro-refining of copper.
(i) What is the cathode made up of?
(ii) Write the reaction that takes place at the anode.

Q. Incorrect statement among the following is:

1. Pig iron contains about 4% carbon
2. Aniline can be used as froth stabiliser in froth floatation process
3. Brass is an alloy of copper and zinc
4. Zirconium is refined by zone refining method

Q. Electrolytic conduction differs from metallic conduction. In case of metallic conduction?

1. The resistance increases with increasing temperature
2. The resistance decreases with increasing temperature
3. The flow of current does not generate heat
4. The resistance is independent of the length of electrolytic conductor.