how many liters of 0.125 M NaOH are needed to contain 0.255 mol NaOH? Solution Answer:- Therefore the formula is, Molarity = moles/ Liters You want to calculate volume so rearrange the above formula to solve for volume Liters = moles / molarity 0.125 = 0.255/ Liters Liters = 0.255 / 0.125 Liters = 2.04 L.