Question

Calcium chloride when dissolved in water dissociates into its ions according to the following equation. 

CaCl₂ (aq) → Ca²⁺ (aq) + 2Cl– (aq) 

Calculate the number of ions obtained from CaCl₂ when 222 g of it is dissolved in water. 

Answer 1

1 mole of calcium chloride = 111g 

∴ 222g of CaCl₂ is equivalent to 2 moles of CaCl₂ 

Since 1 formula unit CaCl₂ gives 3 ions, therefore, 1 mol of CaCl₂ will give 3 

moles of ions 

2 moles of CaCl2 would give 3×2=6 moles of ions. 

No. of ions             = No. of moles of ions × Avogadro number 

                              = 6 × 6.022 ×10²³ 

                             = 36.132 ×10²³ 

                             = 3.6 132 ×10²⁴ ions