Question

Carnallite is a double chloride of K and Mg containing `38.86%` of water. 0.458 g of it gave 0.71 g AgCl and 0.666 g of it gave 0.27 g magnesium pyrophosphate `(Mg_2P_2O_7)`. Calculate the percentage of KCl in the carnallite.

Answer 1

Only `MgCl_2` can give `Mg_2P_2O_7`. Thus, the percentage of `MgCl_2` can be determined.
`2MgCl_2toMg_2P_2O_7`
`0.27g of Mg_2P_2O_7-=(190xx0.27)/(222)=0.231 g of MgCl_2`
`% of MgCl_2=(0.231xx100)/(0.666)-=34.68%`
`% of HCl-=100-(34.68+38.86)-=26.46%`