equivalence weight measurement through metal displacement method.

metals can displace other metals from their salt soln.

it is only due to the electropositivity difference.

the main thing about this is that

mass of metal 1/mass of metal 2
= equivalent weight of metal 1/equivalent weight of metal 2
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double displacement method

substances always react in the ratio of equivalent weight.
eqiuvalent weight of a compound is a;ways equal to the sum of the equivalent weights of the constiuent atom.

AB reacts with CD to form AD and CB
masses of AB and AD is known

mass of AB / mass of AD

=

equivalent weight of AB / equivalent weight of AD

=

equivalent weight of A+equivalent weight B / equivalent weight of A+equivalent weight D

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ELECTROLYSIS METHOD

faradays laws of electrolysis are used to determine the equivalent wt of a substance.

FIRST LAW
The quantity of a substance deposited at a particular electrode by electrolysis is directly proprotional to the quantity of electricty(total charge) used.

Weight(w) Q

(w) I.t

(w)=Z.I.t

Z is the electrochemical eqivalent.

so when I is 1 amp and t is 1 sec
then W = Z.

SECOND LAW


when the same qty of electricity is passed through diff electrolytes connected in series then the masses of the substance liberated at the electrodes are directly proportional to their equivalent weights.

w1/w2 = E1/E2

Z1 It/Z2 It= E1/E2

therefore

Z1/Z2= E1/E2

Z E (Z is directly proportional to E)

or E= F x Z

 F is faradays constant

value of F = 96500 C

Z= E/F

Z= E/ 96500

CALCULATION OF ELECTROVALENT WEIGHT
i> using I law

W= Z I t

Z= E/F
therefore

W= (E/F) x It

ii> using II law

W1/W2= E1/E2
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