Molarity is Given as,
Molarity = Moles / Volume of Solution --- (1)
Data Given:
Molarity = 0.250 mol.L⁻¹
Volume = 450 mL = 0.45 L
Solving equation 1 for Moles,
Moles = Molarity × Volume
Putting values,
Moles = 0.250 mol.L⁻¹ × 0.45 L
Moles = 0.1125 mol
Now, converting moles into grams,
As,
Moles = Mass / M.mass
Or,
Mass = Moles × M.mass
Mass = 0.1125 mol × 142 g.mol⁻¹
Mass = 15.97 g
Result:
Molar Mass of Na₂SO₄ = 142 g.mol⁻¹
Moles needed = 0.1125 mol
