The molecular formula of a commercial resin used for exchanging ions

• Stoichiometry

The molecular formula of a commercial resin used for exchanging ions in water softening is C₈H₇SO₃Na (Mol. Wt. 206). What would be the maximum uptake of Ca²⁺ ions by the resin when expressed in mole per gram resin?

1. 2/309
2. 1/103
3. 1/206
4. 1/412

Answer

2C₈H₇SO₃Na + Ca²⁺  → (C₈H₇SO₃)Ca

2 mole         1 mole
412 gm        1 mole

Maximum uptake of Ca⁺² ions by the resin = 1/412 (mole per gm resin)

The correct option is D.