How many moles of calcium chloride (CaCl2) are needed to react completely with 6.2 moles of silver nitrate (AgNO3) ?

2AgNO3 + CaCl2 → 2AgCl + Ca (NO3) 2

The no. of moles of CaCl₂ are needed = 3.1 mol.

Explanation:

From the balanced reaction:

2AgNO₃ + CaCl₂ → 2AgCl + Ca (NO₃) ₂,

It is clear that 2 mol of AgNO₃ react with 1 mol of CaCl₂ to produce 2 mol of AgCl and 1 mol of Ca (NO₃) ₂.

Using cross multiplication:

2 mol of AgNO₃ need → 1 mol of CaCl₂ to react completely, from stichiometry.

6.2 mol of AgNO₃ need →? mol of CaCl₂ to react completely.

∴ The no. of moles of CaCl₂ are needed = (1 mol) (6.2 mol) / (2 mol) = 3.1 mol.