In the analysis of 0.1 of sample of feldspar, 0.118 g of mixture of NaCl and KCl is obtained which on treatment with `AgNO_3` gives 0.2451 of AgCl. Calculate the precentage of `Na_2O` and `K_2O` in feldspar.

Explanation

Let the amount of sodium chloride be a gram.
The amount of potassium chloride is `(0.1180-a)g`.
`NaCl+AgNO_(3)toAgCl+NaNO_(3)`
`NaCl-=AgNO_(3)` formed is
`(a)/(58.5)xx143.5`
`KCl+AgNO_(3)toAgCl+KNO_(3)`
`KCl-=AgNO`
The mass of `AgNO_(3)` formed is
`((0.1180-a))/(58.6)xx143.6`
`therefore[(a)/(58.5)xx143.5]+[((0.1180-a))/(74.5)xx143.5]=0.2451`
On solving we get
`a=0.0338` (mass of NaCl)
`Na_(2)O-=2NaCl`
`therefore(W_(Na_(2)O)/(62)=(0.0038)/(2xx58.5)`
or `W_(Na_(2)O)=0.0179g`
Percentage of `Na_(2)O=(0.079xx100)/(0.500)=3.58%`
`(0.1180-a)=(mass of KCl)`
`(0.1180-0.0338)=0.0842g` (mass of KCl)
`K_(2)O-=2NaCl`
`(W_(K_(2)O)/(94)=(0.0038)/(2xx74.5)`
or `W_(K_(2)O)=0.031g`
percentage of `K_(2)O=(0.0531xx100)/(0.500)=10.62%`