Calculate the amount of benzoic acid required for preparing 250mL of 0.15M solution in methanol.
Volume of the solution = 250mL = 0.25L
Let the no. Of moles of solute be n
Molarity = No. of moles of solute/volume of solution
⇒ 0.15 = n/0.25
⇒ n = 0.0375moles
Molar mass of C6H5OH = 6×12 + 5×1 + 16 + 1 = 94g
Moles = mass/molar mass
⇒ 0.0375 = m/94
Mass of benzoic acid required = 3.525g.