CHEM 1050 Chapter : Electrolytic Cells.docx

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2 May 2012

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Electrochemical cell in which an electric current drives an otherwise non-spontaneous reaction. Electrolysis- process of producing a chemical change in an electrolytic cell. Salts are melted to liquids, metal component of salt forms on cathode and gas evolves at the anode. When electrolyzing aqueous solution of ionic compound must consider possibility of water involved at one or both electrodes: water can be reduced or oxidized. Species whose oxidation half-reaction has the larger (less negative) oxidation potential is the more easily oxidized. Electroplating zinc is important for the protection from corrosion of metals. Coating steel by cathodic protection even when the zinc coat is scratched. Electrogalvanization- how a thin zinc coating applied to steel. Electrolysis is used to purify metals eg. copper for electrical use must be very pure and purified through electrolysis. The quantity of substance liberated at an electrode is directly proportional to the quantity of electric charge than has flowed in the circuit, 2.

Related Questions

In chemistry, we did an electrolysis lab. We created anelectrolytic cell with a DC power supply, two graphite electrodes,and aqueous Na2SO4 solution.

What half reaction would occur at the anode?

Thanks

Electrolysis is carried out on a solution of silver nitrate for2.00 h. The platinum cathode, which has a mass of 25.0782 g, weighs25.2794 g after the electrolysis. The platinum anode weighs thesame before and after the electrolysis.

a) draw diagram of electrolytic cell. include charges andhalf-reactions occuring at each electrode, and show the directionelectrons are flowing.

b) What must have been the magnitude of the current used in thiselectrolysis?

c) What minimum voltage must have been used in thiselectrolysis? Assume standard conditions.

d) What volume of gas forms at the anode if it is measured at 25degrees celsius and 755mmHg?

Please show work. Answers are: (b) 0.0250 A (c) 0.43 V (d) 11.5ml of O2

1) A constant current of 0.800 A is run through the electrolytic cell in order to produce oxygen (gas) at the anode:

2 H₂O â O₂(g) + 4 e^- + 4 H⁺

The amount (in grams) of O₂ obtained after 15.2 min of electrolysis is [X] g

2) Electrolysis of a solution of Tl³⁺ produces deposition of elemental thallium, Tl, at the cathode. The time (in min.) needed for a constant current of 1.20 A to deposit 0.500 g of Tl(s) is [X] min.

3) An electrochemical cell is described by the following line notation:

Zn(s) Ç Zn²⁺(aq) (0.0420 M) ÇÇ Tl³⁺(aq) (9.06Ã10^-2 M), Tl⁺(aq) (0.0400 M) Ç Pt(s).

Given: EÂ°(Zn²⁺/Zn) = - 0.763 V; EÂ°(Tl³⁺/Tl⁺) = + 1.25 V.

The potential on the cathode half-cell, E₊ = V; the potential on the anode half-cell, E_- = V; and the overall cell potential, E_cell = V.

4) Consider electrolysis of molten copper bromide, CuBr₂. What is the product of this process obtained (a) at the cathode? (b) at the anode?

1. a) Cathode: Cu(s);
(b) Anode: Br₂(l)

2. (a) Cathode: Br₂(l);

(b) Anode: Cu(s)

3. (a) Cathode: Cu²⁺;

(b) Anode: Br^-

4. (a) Cathode: Br^-;

(b) Anode: Cu²⁺

5. (a) Cathode: Cu(s);

(b) Anode: O₂(g)

6. (a) Cathode: H₂(g);

(b) Anode: Cu²⁺

CHEM 1050 Chapter : Electrolytic Cells.docx

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