The molecular formula of a commercial resin used for exchanging ions in water softening is `C_(8)H_(7)SO_(3)Na` (molecular weight = 206). What would be the maximum uptake of `Ca^(2+)` ions by the resin if expressed in mol per gm?

Options

A. `1/412`
B. `1/103`
C. `1/206`
D. `2/309`

Answer

A

Explanation

`2C_(8)H_(7)SO_(3)Na (aq) + Ca^(2+) (aq) to (C_(8)H_(7)SO_(3))_(2) Ca(aq) + 2Na^(+)` (aq)
1 mol calcium ion reacts with 2 moles of resin 2 mol (resin) = 412 gresin = 40 g `Ca^(2+)` ions = 1 mol of `Ca^(2+)` ion
`therefore` Moles of `Ca^(2+)` per g of resin = `1/412`