Li occupies a higher position in the electrochemical series of metals as compared to Cu since :
the standard reduction potential of Li+/Li is lower than that of Cu2+/Cu
the standard reduction potential of Cu2+/Cu is lower than that of Li+/Li
the standard oxidation potential of Li+/Li is lower than that of Cu2+/Cu
Li is smaller in size as compared to Cu
A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH=10 and by passing hydrogen gas around the platinum wire at 1 atm pressure. The oxidation potential of electrode would be
0.059 V
0.59 V
0.118V
1.18V
At 25°C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm-1cm2 mol-1 and at infinite dilution its molar conductance is 238 ohm-1cm2 mol-1. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is
2.080%
20.800%
4.008%
40.800%
The quantity of electricity needed to separately electrolyze 1 M solution of ZnSO4 , AlCl3 and AgNO3 completely is in the ratio of
2 : 3 : 1
2 : 1 : 1
2 : 1 : 3
2 : 2 : 1
On passing C ampere of current for the time 't' sec through 1 L of 2 (M) CuSO4 solution (atomic weight of Cu= 63. 5), the amount 'm' of Cu (in gram) deposited on cathode will be
m = Ct/(63.5 x 96500)
m = Ct/(31.25 X 96500)
m = (C x 96500)/(31.25 x t)
m = (31.25 X C x t)/96500
The two half-cell reactions of an electrochemical cell is given as
Ag+ + e- → Ag; = -0.3995 V
Fe2+ → Fe3+ + e- ; = -0.7120 V
The value of cell EMF will be
-0.3125 V
0.3125 V
1.114 V
-1.114 V
At 25°C, the molar conductance of 0.007 M hydrofluoric acid is 150 mho cm2mol-1 and its Λ°m = 500 cm2mol-1. The value of the dissociation constant of the acid at the given concentration at 25°C is
7 × 10-4 M
7 × 10-5 M
9 × 10-3 M
9 × 10-4 M
The standard reduction potential Eo for half-reaction are:
Zn Zn2+ + 2e- ; E° = + 0.76V
Fe Fe2+ + 2e- ; E° = + 0.41 V
The EMF of the cell reaction
Fe2+ + Zn Zn2+ + Fe is :
- 0.35 V
+ 0.35 V
+ 1.17 V
- 1.17 V
The formal potential of Fe3+ /Fe2+ in a sulphuric acid and phosphoric acid mixture (E° = +0.61 V) is much lower than the standard potential (E° = +0.77 V). This is due to
formation of the species [FeHPO4]+
lowering of potential upon complexation
formation of the species [FesO4]+
high acidity of the medium
A.
formation of the species [FeHPO4]+
B.
lowering of potential upon complexation
D.
high acidity of the medium
Since, H2SO4 and H3PO4 both are strong acids so their presence makesthe medium more acidic. The Fe ions form complex, [FeHPO4]+ with these acid and hence,the concentrationof Fe3+ ion reduces which results in lowering in the formal reduction potential.