First Law of Electrolysis.
Definition-It states that the mass of a substance deposited at the electrodes during electrolysis is directly proportional to the quantity of electricity passing through the electrolytes
By variation: M is directly proportional to Q
Where M=mass of substance
Deposited in grammes(g)
Q- quantity of electricity in Coulomb's
I- Current in amperes
t- Time in second
z- Chemical equivalent
Second law of Electrolysis
Definition- states that when the same auantity of electricity is passed through solution of different electrolytes,the relative number of moles of elements deposited is inversely proportional to their respective charge.
Note: By the mole concept
1 mole of a univalent ion e.g Na+= Relative molecular mass of element =’1 Faraday= 1*96500
From the foregoing,if it is a divalent element like copper e.g Cu2+= 2 Faraday= 2* 96500C
Same for trivalent element,it becomes - 3*96500
Worked out example-
1.For how long must a current of 0.5A be passed through a solution of silver trioxonitrate V solution to deposit 0.01 mole of silver?(Ag- 108, Faraday's constant- 96500C permole)
Equation of reaction
Ag ---- e` ----------------->. Ag+(aq)
1 mole of Ag+(aq)=108g=1F=96500C
1 mole(108g) of Ag+ will produce 96500 of electricity.
So 0.01 mole(108g) of Ag+ will produce = 96500C *0.01= 965C.
Quantity (Q)= Current (I) * time(t) of electricity
965= 0.5 * t
The time is 1930 seconds
Hope you understood?Now you can try out the exercises.use a calculato