Electrochemistry Test - 3

Michael Faraday was the first scientist who described the quantitative aspects of electrolysis.

After his extensive investigations on electrolysis of solutions and melts of electrolytes, Faraday published his results during 1833-34 in the form of the following well known Faraday’s two laws of electrolysis:   

Faraday’s first law of electrolysis states that the amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte (solution or melt).

OR

The mass of the substance (m) deposited or liberated at any electrode is directly proportional to the quantity of electricity or charge (Q) passed.

Copper ions from the copper sulfate are discharged to give a deposit of copper on the cathode in preference to hydrogen ions forming hydrogen gas.

Both conductivity and molar conductivity change with the concentration of the electrolyte. Conductivity always decreases with decrease in concentration both, for weak and strong electrolytes.

This can be explained by the fact that the number of ions per unit volume that carry the current in a solution decreases on dilution.

Molar conductivity increases with decrease in concentration. This is because the total volume, V, of solution containing one mole of electrolyte also increases.

When a metal is placed in a solution of its ions, the metal gains either a positive or negative charge with respect to the solution. Due to this, a definite potential difference is developed between the metal (electrode) and the solution (electrolyte). This potential difference is called electrode potential.

Electric potential is the amount of work needed to move a unit charge from one point to another against an electric field.

The cell potential is the way in which we can measure how much voltage exists between the two half cells of a battery.

The electrochemical cells are used for determining

1) the pH of the solution

2) Solubility product

3) Equilibrium constant

4) Potentiometric titration

5) Thermodynamic properties

If the standard electrode potential of an electrode is greater than zero, then its reduced form is more stable compare to that of hydrogen gas.

And if the standard electrode potential of an electrode is less than zero, the hydrogen gas is more stable than the reduced form of the species.

Inert electrode is an electrode that serves as a source or sinks for electrons without playing a chemical role in the electrode reaction.

The inert electrodes are built from gold and platinum because they are inert (non reactive) metals.

An inert electrode is needed to conduct the electrons but it is not part of the redox reaction.

Both Platinum and Gold are inert metals and are hence used for making these types of electrodes.