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Class 10 Class 12

Electrochemistry

Calculate the emf of the cell in which the following reaction takes place:
Ni(s) + 2Ag⁺ (0.002 M)

\to

Ni²⁺ (0.160 M) + 2Ag(s)
Given that

{E^{o}}_{Cell} = 1.05 V

Answer:

Ni (s) + 2 {Ag}^{+} (aq) \to {Ni}^{2 +} (aq) + 2 As (s)

E_{cell} = {E^{o}}_{cell} + \frac{RT}{2 F} \ln \frac{{[{Ag}^{+} (aq)]}^{2}}{[{Ni}^{2 +} (aq)]}

E_{cell} = {E^{o}}_{cell} + \frac{0.059}{2} \log \frac{{[{Ag}^{+} (aq)]}^{2}}{[{Ni}^{2 +} (aq)]}

The equation is also written as

or

E_{cell} = {E^{o}}_{cell} - \frac{0.059}{2} \log \frac{[{Ni}^{2 +} (aq)]}{{[{Ag}^{+} (aq)]}^{2}} = 1.05 V - 0.0295 \log \frac{0.160}{0.002}

= 1.05 V – 0.0295 x log 80

= 1.05 V – 0.0295 x 1.9031

= 1.05 V – 0.056 = 0.99 V.

1585 Views

Can you store copper sulphate solutions in a Zinc pot?

Answer:

No. Because zinc is more reactive than copper and thus holes will be developed in zinc pot.
Cu²⁺(aq) + Zn(s) → Zn²⁺(aq) + Cu(s)

1384 Views

How would you determine the standard electrode potential of the system Mg²⁺/Mg?

Answer:

Use standard hydrogen electrode as anode and Mg²⁺ | Mg as a cathode we can measure the standard electrodepotential of systemMg²⁺ | Mg. Standard hydrogen electrode, represented by Pt(s), H₂(g) (1 atm) | H⁺ (aq) and dip the electrode of Magnesium wire in a 1M MgSO₄ solution .The standard hydrogen electrode is always zero.

Use formula

E^o_cell = E^o_right – E^o_left

The standard hydrogen electrode is always zero.

So that the value of

E^o_left=0

Hence

E^o_cell = E^o_Mg|Mg2+

E^o_Mg|Mg2+= E^o_cell

2203 Views

Consult the table of standard electrode potentials and suggest three substance that can oxidize ferrous ions under suitable conditions.

Answer:

oxidation of ferrous ion means :

Fe²⁺--> Fe³⁺ +e^- ;

E_{\frac{{Fe}^{3 +}}{{Fe}^{2 +}}}^{0} = 0.77 V

Any substance which standard electrode potential is more than that of Fe⁺³ /F⁺² can oxidise ferrous ions.
(refer to the table given in book)

The EMF of the substance whose reduction potentials greater than 0.77V will oxidised ferrous ion.
for example Br_2,Cl_2,and F₂ .

879 Views

Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.

Answer:

For hydrogen electrode, ,

given that pH = 10

use formula [H⁺] = 10^–pH

so that [H⁺] = 10⁻¹⁰ M

Electrode reaction will

H⁺ + e^– →1/2 H₂

Use the formula

E_{H^{+} / H_{2}} = {E^{o}}_{H}^{+} / H_{2} - \frac{RT}{nF} \ln \frac{[H_{2}]}{[H^{+}]^{2}} = 0 - \frac{8.314 \times 298}{2 \times 96500} \ln \frac{[I]}{{[H^{+}]}^{2}} = 0.05915 \log [H^{+}] = - 0.05915 pH = - 0.05915 \times 10 = - 0.59 V

1279 Views

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Electrochemistry

Consult the table of standard electrode potentials and suggest three substance that can oxidize ferrous ions under suitable conditions.