Electrochemistry

Question 1

Name the type of cell which was used in Apollo Space program

Answer 1

H2-O2 fuel cell

Question 2

State the Faraday”s first law of electrolysis?

Answer 2

The amount of substance deposited or liberated at an electrode is directly proportional to quantity of electricity passed through the electrolyte.
w α Q
w= ZIt
z:Electrochemical equivalent = no of equivalent/F
F=96500C

Question 3

Represent the galvanic cell in which the rxn
Zn(s)+Cu+2(aq) —->Zn+2(aq)+Cu(s) take place

Answer 3

Zn(s)|Zn+2(aq)||Cu+2(aq)|Cu(s)

Question 4

Define Secondary Batteries?

Answer 4

Batteries which can be recharged by passing electric current through by passing electric current through them and hence can be used over and over again.
eg:Lead storage battery

Question 5

Using E value of A and B predict which is better for coating the surface of iron
[E(Fe+2/Fe)=0.44V] to prevent corrosion of iron and why?
E(A+2/A) = -2.37V E(B+2/B)=-0.14V

Answer 5

Metal with higher oxidation potential will get oxidised first.Metal A has higher oxidation potential when connected with iron protect it from oxidation and prevent corrosion.

Question 6

Define the term Molar Conducting(Λ)

Answer 6

Molar Conductivity is the conductance of a volume of solution containing 1 mol of dissolved electrolyte when placed between two parallel electrodes 1 cm apart cross section large enough to contain between them all the solution

Question 7

Define Fuel Cell.

Answer 7

It is a galvanic cell in which chemical energy from combustion of fuels like hydrogen,methane,methanol is converted into electrical energy

Question 8

Write the name of the cell which is generally used in inverters.Write the rxns taking place at anode and cathode of this cell?

Answer 8

Lead Storage Battery
at anode:
Pb(s)+SO4-2(aq)—>PbSO4(s)+2e
PbO2(s)+SO4-2(aq)+4H+ + 2e—->PbSO4(s)+2H2O(l)

Question 9

What is name of cell used in transistors.Write reaction taking place at anode and cathode of this cell.

Answer 9

Leclanchecell(Drycell)
At anode:
Zn(s)—>Zn+2+2e
MnO2+NH4+ + e—->MnO(OH)+NH3

Question 10

Why is AC used instead of DC for measuring resistance of electrolytic solution

Answer 10

DC will cause electrolysis of solution so more ions will be produced.Hence we use AC so that concentration of ions remains same

Question 11

Mercury Cells deliver a constant potential during its life time.Give reason

Answer 11

Mercury cells deliver a constant potential during its life time because overall rxn does not involve ions on solution whose concentration can change
Zn(Hg)(s)+HgO(s)—->ZnO+Hg(l)