Q.

Following limiting molar conductivities are given as:  

λm(H2SO4)=x S cm2 mol-1

λm(K2SO4)=y S cm2 mol-1

λm(CH3COOK)=z S cm2 mol-1

λm (in S cm2 mol-1) for CH3COOH will be                   [2019]

1 x-y+2z  
2 x+y-z  
3 x-y+z  
4 (x-y)2+z  

Ans.

(4)

According to Kohlrausch's law,  

Λmo for CH3COOH =λCH3COO-+λH+

Λ° for H2SO4 =2λH++λSO42-=x S cm2 mol-1             ...(i)

Λ° for K2SO4 =2λK++λSO42-=y S cm2 mol-1             ...(ii)

Λ° for CH3COOK =λCH3COO-+λK+=z S cm2 mol-1        ...(iii)

On adding equation (i) and 2×(iii) and subtracting (ii), we get  

2λH++λSO42- +2λCH3COO- +2λK+ -2λK+ -λSO42- =x+2z-y

2λH++2λCH3COO-=x+2z-y

λH++λCH3COO- =(x-y)2+z