`A" " 5.0 g` sample of felspar containing `Na_(2)O,K_(2)O` and some inert impurity is dissolved in dilute `HCl` solution and `NaCl` and `KCl` formed are separated by fractional crystallization. During crystallization some less soluble impurities also come out. Mass of `NaCl, KCl` and impurity accompanying these salts was found to be `6.47 g`. Solid crystal was then re-dissolved and required `300mL` of `0.3M AgNO_(3)` for complete precipitation of chlorides. The precipitate this, obtained ws found to contain `4.23%` insoluble impurity. Determine mass percentage of `Na_(2)O` and `K_(2)O` in the original sample:

Answer

`31.16,37.34`

Explanation

Mass of `AgCl=0.09xx143.5=12.915g` which is `95.77%` of total `ppt`.
implies total mass of precipitate `=13.485g` and mass of impurity `=0.57g`
implies Mass of `NaCl + KCl = 5.9 g`
`implies x=2.94 g NaCl,2.96 g KCl`
`m(Na_(2)O)=1.558 g implies m%(Na_(2)O)=31.16`
`m(K_(2)O) =1.867 g implies m% (K_(2)O)=37.34`