Electricity & Megnetism

# chemical effects of electric current

### Voltmeter or coulomb meter:

The vessel in which electrolytes are carried out. It is also called electrolytic cell.

### What is Electrolyte?

An ionic compound in Aquas solution or molten state is called an electrolyte.

### What is Electrolysis?

On passing a current through an electrolyte, chemical changes occur in the electrolyte, and substances are liberated at the electrodes. This process is called electrolysis.

#### First law:

The mass of a substance liberated on the electrode is proportional to the current passed through it and proportional to the time for which the current is passed.
m ∝ I
and                                          m ∝ t
Or                                           m=zIt
Where z is called electrochemical equivalent.
Since It = Q
m=ZQ
Z =Chemical equivalent in gram/1 Faraday
Faraday (F): It is the amount of charge on 1 mole of electrons =96485 Practically we use 1F =96500 c.

#### Second law:

If the same quantity of electricity is based on different electrolytes, the mass of the substances deposited at the respective cathodes is directly proportional to the chemical equivalent.
Note 1 Faraday of charge will liberate 1 gram equivalent any substance during electrolysis.
Electrolytic cell or voltmeter may be used to measure current more accurately than ammeters.

#### Back emf:

It is the potential difference opposite to the thermal emf set up due to the accumulation of ions around the double electrodes. The back emf depends upon the nature of the electrodes and the concentration of ions.