Some Basic Concepts Of Chemistry

  • Question

    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?

    • 1/103

    • 1/206

    • 2/309

    • 1/412




    We know the molecular weight of C8H7SO3Na
    = 12x8+1x7+32+16x3+23 = 206
    we have to find mole per gram of resin
    1 g of C8H7SO3Na has number of mole
    equals fraction numerator weight space of space given space resin over denominator Molecular space weight space of space resin end fraction
    =1/206 mol
    Taking the reaction,
    C8H7SO3Na + Ca2+ → (C6H7SO3)2Ca + 2Na+
    therefore, 2 moles of C8H7SO3Na  combines with 1 mol of Ca2+
    Thus, 1 mole of C8H7SO3Na will combine with 0.5 mol of Ca2+
    Hence, 1/206 mole of C8H7SO3Na will combine with,
     0.5 x (1/206)mol of Ca2+ = 1/412 mol Ca2+

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