The molecular fomula of a commercial resin used for exchanging ions in water softening is `C_8 H_7 SO_3 Na` (Mol. Wt. 206). What would be the maximum uptake of `Ca^(2+)` ions by the resin when expressed in mole per gram resin ?

Explanation

`underset(2 "mol")(2C_8 H_7) SO_3 Na + underset(1 "mol")(Ca^(2+)) to (C_8 H_7 SO_3^(-)) Ca + 2Na^(+)`
2 mol of `C_8 H_7 SO_3` Na require 1 mol of `Ca^(2+)`
`2 xx 206 gg` of `C_8 H_7 SO_3` Na = 1 mol of `Ca^(2+)`
1 g of `C_8 H_7 SO_3 Na = 1/(412) ` mol
`therefore ` Maximum uptake `=(1)/(412)` mol per gram.