Question

Calculate the mass of maleic acid required to prepare 250 mL of a 0.05M solution. (I got 1.45 grams). This is the part I'm confused on: How many millimoles of the acid are contained in a 25 mL aliquot?

Answer 1

Molarity is an intrinsic quantity hence it doesn't change with the amount of solution. If 25 ml aliquot is taken out of 250 ml 0.05M solution then the 25ml aliquot will also have molarity 0.05 M

Hence, as we know Molarity= (number of millimoles/volume of solution in milliliter)

Putting values, molarity =0.05 M , Volume =25ml

0.05M= no of millimoles/25ml

hence no. of millimoles= 0.05 M25ml = 1.25 mmoles

Hence no. of millimoles in 25ml aliquot will be 1.25 mmoles