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Electrochemistry

Short Answer Type

281. How long will it take to deposit electrolytically 127 gm of copper on the cathode of a copper voltameter by a current of 50A? Given ECE of copper = 0.0003294 g/c.

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282. An electric current of 0.5 ampere was passed through acidulated water for one hour. Calculate the volume of hydrogen at STP produced. 1 coulomb of electricity deposits 0.00001 gm of hydrogen.

648 Views

Long Answer Type

283.

How much charge is required for the following reduction of
(i) 1 mol of Al³⁺ to Al
(ii) 1 mol of Cu²⁺ to Cu
(iii) 1 mol of MnO₄^–to Mn²⁺

326 Views

Short Answer Type

284. A solution of CuSO₄ is electrolysed for 10 minutes with a current of 1.5 amperes. What is the mass of copper deposited at the cathode? (at mass Cu = 63.5).

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285. A solution of CuSO₄ is electrolysed for 10 minutes with a current of 1.5 amperes. What is the mass of copper deposited at the cathode?

1025 Views

286. Represent the cell in which the following reaction takes place:
Mg(s) + 2Ag⁺ (0.0001 M) → Mg²⁺(0.130 m) + 2Ag(s)
Calculate its E_(cell), if E°_cell = 3.17 V.

831 Views

Long Answer Type

287.
A Cell is prepared by dipping a copper rod in 0.01 M copper sulphate solution, and zinc rod in 0.02 M ZnSO₄ solution. The standard reduction potentials of copper and zinc are + 0.34 V and – 0.76 V respectively.
(a) What will be the cell reaction?
(b) How will the cell be represented?
(c) What will be the emf. of the cell?

(a) As E°_Zn²⁺/Zn < E°_Cu²⁺/Cu . Zinc electrode acts as anode and copper electrode acts as a cathode. The cell reaction is
Zn(s) + Cu²+(aq) (0.01 M) → Zn²⁺(aq) (0.02 M) + Cu(s)
(b) The cell is represented as
Zn(s) | Zn²+(aq) (0.02 M) || Cu²+(aq) (0.01 M) + Cu(s)
(c) The emf of the cell can be calculated by using Nernst equation
$E = E ° - \frac{0.059}{n} \log \frac{[{Zn}^{2 +}]}{[{Cu}^{2 +}]} E = + 1.10 - \frac{0.059}{2} \log (\frac{0.02}{0.01}) E = + 1.10 - \frac{0.059}{2} \times 0.301 E = + 1.10 - 0.0089 or E = + 1.091 V$

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288. Calculate the standard electrode potential of the Mg²⁺/ Mg electrode for a cell in which the cell reaction is
Mg(s) + 2Ag⁺(aq) → Mg²⁺(aq) + 2Ag(s)
Given that, [Mg²⁺] = 0.1 M, [Ag⁺] = 0.01 M
E°_Ag/Ag = + 0.80, E_cell = + 2.90 V

991 Views

289.

Write the Nernst equation and calculate the emf of the following cell at 298 K:
Pt(s) | Br₂ (l) Br^–(0.01M) || H⁺ (0.03 M) | H₂(g) (1 bar) | Pt(s)
Given E°_Br2/Br– = + 1.08 V
Br₂/ Br^–

486 Views

Short Answer Type

290. Calculate the equilibrium constant of the reaction

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

given : E⁰ =0.46 temperture 25⁰ C

189 Views