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Class 10 Class 12
Calculate the standard cell potentials of galvanic cell in which the following reactions take place:
Fe2+ (aq) + Ag+ (aq) → Fe3+(aq) + Ag(s)
Calculate the ΔrG° and equilibrium constant of the reaction.

The galvanic cell of the given reaction is represented as
Fe2+(aq) | Fe3+(aq) || Ag| Ag(s)
The formula of standard cell potential is
Eocell = Eo right  – Eoleft
Eocell = 0.80 – 0.77
Eocell =  + 0.03 V
In balanced reaction there are 1 electron are transferring so that n = 1
Faraday constant, F = 96500 C mol−1
Eocell = + 0.03 V
Use formula
rGθ = – nFEocell
Plug the value we get
Then, = −1 × 96500 C mol−1 × 0.03 V
= −2895 CV mol−1
= −2895J mol−1
= −2.895 kJ mol−1
Again,
Use second formula of ∆rGθ
rGθ = −2.303RT log kC
log KC = (∆rGθ) /( – 2.303RT)
plug the values we get

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

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

1279 Views . 3 Shares

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

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
Eocell = Eo right  – Eoleft
The standard hydrogen electrode is always zero.
So that the value of
Eoleft =0
Hence
Eocell = Eo Mg|Mg2+
Or
Eo Mg|Mg2+= Eocell
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Consult the table of standard electrode potentials and suggest three substance that can oxidize ferrous ions under suitable conditions.

oxidation of ferrous ion means :

Fe2+--> Fe3+ +e-
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 Br2, Cl2,and F2 .

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Can you store copper sulphate solutions in a Zinc pot?

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)
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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

$\mathrm{Ni}\left(\mathrm{s}\right)+2{\mathrm{Ag}}^{+}\left(\mathrm{aq}\right)\to {\mathrm{Ni}}^{2+}\left(\mathrm{aq}\right)+2\mathrm{As}\left(\mathrm{s}\right)$

or

The equation is also written as

or

= 1.05 V – 0.0295 x log 80

= 1.05 V – 0.0295 x 1.9031

= 1.05 V – 0.056 = 0.99 V.

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