Calculate the mass of oxalic acid dihydrate needed to prepare 500 mL of a 0.02 M aqueous solution. (Molar mass of H₂C₂O₄ 2H₂O = 126 g mol ⁻¹ )

Step-by-step solution

Molarity of the solution is given by M = n V , where n is the number of moles of solute and V is the volume of the solution in liters. Given M = 0.02 M and V = 500 mL = 0.5 L . Number of moles of oxalic acid dihydrate required is n = 0.02 0.5 = 0.01 mol . Molar mass of oxalic acid dihydrate ( H₂C₂O₄ 2H₂O ) is 126 g mol ⁻¹ . Mass required = n Molar mass = 0.01 126 = 1.26 g . Answer: 1.26 g