Electrolytic Refining

Q. Why are Metal Sols. Such as Gold Sol. Negetively Charged?

Q. Which of the following is redox reaction?
(1) AgNO3
+ NaCl  AgCl + NaNO3
(2) CaCO3
+ H2SO4  CaSO4
+ CO2
+ H2O
(3) 2Na + 2H2O  2NaOH + H2
(4) Cu(OH)2
+ 2HCl  CuCl2
+ 2H2O

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. 34. Which of the following is not intramolecular redox reaction? 1) NH4NO2-------->N2+2H2O 2) 2Mn2O7--------->4MnO2+3O2 3) 2KClO3----------->2KCl+3O2 4) 2H2O2----------->2H2O+O2

Q.

How is electrolysis is useful in the purification of metals and electrotyping? Explain.

Q.

In electrolytic refining, the impure metal acts as anode.

1. True

2. False

Q. 9. Oxidation contain electropositive or electronegative? And in which of this(electropositive or electronegative) gain loss of electrons occurs?

Q. Which one of the following is most electrophilic in nature ? (A)CH3+ (B) O=N+ (C) NO2+ (D)CH3•

Q. Four alkali metals $A,B,C$ and $D$ are having standard electrode potentials 3.05, -1.66, -0.40 and 0.80V respectively. Which one will be the most reducing agent?

1. $C$
2. $D$
3. $B$
4. $A$

Q. Native silver metal forms a water soluble complex with a dilute aqueous solution of NaCN in the presence of
(IIT-JEE, 2008)

1. Nitrogen
2. Oxygen
3. Carbon dioxide
4. Argon

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.

In an electrolytic cell, oxidation happens at __

Q.

In an electrochemical cell represented as,

Zn | Zn²⁺₍c₁₎ || Cu²⁺₍c₂₎ | Cu

So in this cell,

a.Zn is oxidized

b.Zn is reduced

c.Cu is oxidized

d.Cu is reduced

Q. Which of the following forms nitride very easily?

1. $K$
2. $Li$
3. $Na$
4. $Cs$

Q. 27. in pcl five decomposition at final mole why will not take two mines to alpha

Q. { 44. In which of the following reactions, }H_2O_2 acts }} as oxidising agent? }{ 1) }Cl_2+H_2O_2→2HCl+O_2}{ 2) }Ag_2O+H_2O_2→2Ag+H_2O+O_2}{ 3) }2NaOH+H_2O_2→ Na_2O_2+2H_2O}{ 4) }KNO_2+H_2O_2→ KNO_3+H_2O

Q. In the reaction2K_3\lbrack Fe(CN)_6\rbrack +2KOH +H_2O_2→2K_4\lbrack Fe(CN)_6\rbrack +2H_2O+O_2, H_2O_2 acts as(1) Reducing agen(2) Oxidising agent(3) Knocking agent(4) Bleaching agent