Dichromate ion in acid solution oxidizes stannous ion as:
`3Sn^(2+)+14H^(+)+Cr_(2)O_(7)^(2-)rarr3Sn^(+)+2Cr^(3+)+7H_(2)O`
(a) If `SnCl_(2)` is the source of `Sn^(2+)`, how many `g` of `SnCl_(2)` would be contained in `2 "litre"` of `0.1N` solution?
(b) If `K_(2)Cr_(2)O_(7)` is the source of `Cr_(2)O_(7)^(2-)`, what is the normality of solution containing `4.9 g K_(2)Cr_(2)O_(7)` in `0.1 "litre"` of solution?

Explanation

For `Sn, Sn^(2+)rarrSn^(4+)+2e`
For `Cr_(2)O_(7)^(2-), 6e+Cr_(2_^(6+)rarr2Cr^(3+)`
(a) Meq.of `SnCl_(2)=2000xx0.1`
`therefore (w)/(E)xx1000 =200`
`therefore (w)/(189.7//2)xx1000=200 [ because E_(SnCl_(2)=(M_(SnCl_(2))/(2)]`
`therefore w_(SnCl_(2)=18.97 g`
(b) Normality of `K_(2)Cr_(2)O_(7)=(4.9)/(M//6)xx(1)/(0.1)( N =(Eq.)/("litre"))`
`=(4.9)/(294//6xx0.1)=1`