Question

Calculate the concentration of all ions present in each of the following solutions of strong electrolytes.

(a) 0.260 mole of Ca(NO₃)₂ in 100.0 mL of solution
(b) 5.5 moles of Na₂SO₄ in 1.25 L of solution
(c) 5.00 g of NH₄Cl in 490.0 mL of solution
(d) 1.00 g K₃PO₄ in 300.0 mL of solution

Answer 1

To find the concentration of ions in solutions of strong electrolytes, calculate the number of moles of each ion generated upon complete dissociation, then divide by the volume of solution to get molarity.

Step-by-step explanation:

To calculate the concentration of all ions present in the given solutions, we need to know the moles of solute and the volume of the solution. The dissolution of strong electrolytes produces ions at a predictable ratio based upon the compound's formula. The concentration is then calculated by the number of moles of ions present per liter of solution.

Examples:

• For Ca(NO3)2, which dissociates into one Ca2+ ion and two NO3− ions for every formula unit dissolved, the total concentration of ions will be the sum of concentrations of each ion generated.
• For Na2SO4, which dissociates into two Na+ ions and one SO42− ion per unit, the concentration of Na+ ions will be twice that of the sulfate ions.