the molecular formula of 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 ?..

To determine the maximum uptake of Ca²⁺ ions by the resin with the molecular formula C8H7SO3Na, we need to analyze the chemical structure and the stoichiometry involved in the ion exchange process. This resin is typically used in water softening applications, where it exchanges sodium ions (Na⁺) for calcium ions (Ca²⁺) present in hard water.

Understanding Ion Exchange

In ion exchange, the resin contains fixed charges that attract and hold onto cations (positively charged ions) like Na⁺ and Ca²⁺. When hard water passes through the resin, the Na⁺ ions are displaced by Ca²⁺ ions, effectively softening the water.

Calculating the Maximum Uptake

To find out how many moles of Ca²⁺ can be exchanged per gram of resin, we first need to establish the molar mass of the resin and the stoichiometry of the exchange reaction.

• The molecular weight of the resin (C8H7SO3Na) is given as 206 g/mol.
• Each molecule of resin can exchange one Na⁺ ion for one Ca²⁺ ion.

Thus, the maximum uptake of Ca²⁺ ions can be calculated using the following steps:

Step 1: Determine Moles of Resin per Gram

Since the molar mass of the resin is 206 g/mol, the number of moles of resin in 1 gram can be calculated as follows:

Moles of resin per gram = 1 g / 206 g/mol

This simplifies to approximately 0.00485 moles of resin per gram.

Step 2: Relate Moles of Resin to Moles of Ca²⁺

Since each mole of resin can exchange one mole of Ca²⁺, the moles of Ca²⁺ that can be taken up by 1 gram of resin is equal to the moles of resin:

Moles of Ca²⁺ per gram of resin = Moles of resin per gram

Thus, the maximum uptake of Ca²⁺ ions is also approximately 0.00485 moles per gram of resin.

Final Result

In summary, the maximum uptake of Ca²⁺ ions by the resin C8H7SO3Na, when expressed in moles per gram of resin, is about 0.00485 moles/g. This value indicates how effectively the resin can soften water by replacing calcium ions with sodium ions, which is crucial for various applications in water treatment.