Chemical engineers describe the concentrations of solutions in terms of their molarity. This describes, rather than the mass of solute that exists per unit volume, the amount of solute in moles per unit volume. This is more useful when you must calculate the volumes of solutions necessary to react with one another. A hundred cubic centimeters of one molar (1M) sodium hydroxide solution, for instance, will completely neutralize 100 cc of 1M hydrochloric acid solution.
Determine the sodium hydroxide's concentration. This value will be printed on the solution bottle's label. For this example, imagine a solution of 1.5M NaOH.
Convert the solution's volume to liters. If you have, for instance, 100 cubic centimeters of solution, divide by 1,000 -- 100 / 1,000 = 0.1 liters.
Multiply the solution's molarity by its volume -- 1.5 x 0.1 = 0.15 moles. This is the number of moles of sodium hydroxide in the solution.
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