(1b) Calculate the concentration in mol/dm³ of a solution containing 355 g of Na₃PO₄ in 3.5 dm³ of solution. Molar mass of Na₃PO₄ Na₃PO₄ = (3 × 23.0) + 31.0 + (4 × 16.0) = 69.0 + 31.0 + 64.0 = 164.0 g/mol Number of moles Moles = Mass / Molar Mass = 355 g / 164.0 g/mol ≈ 2.165 mol Concentration Concentration = Moles / Volume = 2.165 mol / 3.5 dm³ ≈ 0.619 mol/dm³ Final Answer: 0.619 mol/dm³