IIT JEE-AIEEE 2012, Entrance Notifications, Study Tips, Engineering Preparation, Practice Test Papers, Experts Advice

Himanshu

some points about transport number....

first of all wat is transport no - the current flowing. through an electrolytic sol. is carried by the ions . the fraction of the current carried by an ion is called transport number or transference number , as the current carried by an ion depends upon its speed , hence

transport no. of cation n_c = current carried by cation / total current = u_c / u_c + u_a

transport no. of anion n_a = current carried by anion / total current = u_a / u_c + u_a

n_c + n_a = 1

2)Effect of concentration and temp. on transport no. - with increase in concentration , transport no. decreases . Further fr 1:1 electrolyte , if transport no. of an ion is greater than 0.5 , it decreses with increase in temp , but if it is less than 0.5 , it increases with increase in temp. till it aquires the value of 0.5

3)It depends upon the size of the ions

see for example NaCl and HCl

as size of Na⁺ is greater than H⁺ , so transport no. of Cl^- in HCl is less than in NaCl

*4)* Li⁺ is smaller in size than Na⁺ , so theoratically , its T. No must be greater than Na⁺ , but in actual position , its otherwise , this is bcoz Li⁺ is much more hydrated than Na⁺ , for the same reason T No. of Na⁺ is less than K⁺

FARADAY's 1st and 2nd LAW COMBINES TO GIVE THIS RELATION...

W = ZQ = E*Q / F = (Q/F) * M/z = (C*t/F) * (M/z)

Z = electrochemical equivalent

Q = qty. of electricity passes

E = eq. wt of the metal

F = 1 faraday

M = atomic mass of the metal

z = valency of the metal

C = current passed

t = time for wich the current is passed

hope these pts helps u in ur preprations....

ALL THE BEST :)

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