In the extraction of sodium by Down's process, cathode and anode respectively are
copper and nickel
copper and chromium
nickel and chromium
iron and graphite
The standard reduction potentials of Zn2+| Zn, Cu2+| Cu and Ag+| Ag are respectively -0.76, 0.34 and 0.8 V. The following cells were constructed :
(1) Zn | Zn2+ || Cu2+ | Cu
(2) Zn | Zn2+ || Ag+ | Ag
(3) Cu | Cu2+ || Ag+ |Ag
What is the correct order of E of these cells?
2 > 3 > 1
2 > 1 > 3
1 > 2 > 3
3 > 1 > 2
What is the quantity of electricity (in Coulombs) required to deposit all the silver from 250 mL of 1 M AgNO3 solution?
2412.5
24125
4825.0
48250
Which of the following is not correct?
Aqueous solution of NaCl is an electrolyte
The units of electrochemical equivalent are g-Coulomb
It the Nernst equation, n represents the number of electrons transferred in the electrode reaction.
Standard reduction potential of hydrogen electrode is zero volt
What is the time (in sec) required for depositing all the silver present in 125 mL of 1 M AgNO3 solution by passing a current of 241.25 A? (1F = 96500 coulombs)
10
50
1000
100
Electrolysis of X gives Y at anode. Vacuum distillation of Y gives H2O. The number of peroxy (O-O) bonds present in X and Y respectively are :
1, 1
1, 2
zero, 1
zero, zero
Assertion (A) : A current of 96.5 A is passed into aqueous AgNO3 solution for 100 s. The weight of silver deposited is 10.8 g (At. wt. of Ag = 108)
Reason (R) : The mass of a substance deposited during the electrolysis of an electrolyte is inversely proportional to the quantity of electricity passing through the electrolyte.
The correct answer is :
Both (A) and (R) are true and (R) is the correct explanation of (A).
Both (A) and (R) are true but (R) is not the correct explanation of (A).
(A) is true but (R) is false.
(A) is false but (R) is true.
When same quantity of electricity is passed through aqueous AgNO3 and H2SO4 solutions connected in series, 5.04 × 10-2 g of H2 is liberated. What is the mass of silver (in grams) deposited ? (Eq. wts. of hydrogen = 1.008, silver = 108)
54
0.54
5.4
10.8
When electric current is passed through acidified waterfor 1930 s, 1120 mL of H2 gas is collected (at STP) at the cathode. What is the current passed in amperes ?
0.05
0.50
5.0
50
C.
5.0
Electrolysis of water takes place as follows-
H2O
At anode
4 OH → 2H2O + O2
At cathode
2H+ + 2e- H2
Given, time, t = 1930 s
Number of moles of hydrogen collected
=
= 0.05 moles
1 mole of hydrogen is deposited by 2 = moles of electrons
0.05 moles of hydrogen will be deposited by = 2 × 0.05 =0.10 mole of electrons.
Charge, Q = nF
= 0.1 × 96500
Charge, Q = i.t
0.1 × 96500 = i × 1930
i = = 5.0 A
Calculate the emf of the cell Cu(s)|Cu2+(aq)|| Ag+ (aq)| Ag(s). Given .
+0.46 V
+1.14 V
+0.57V
-0.46 V