How many moles of solute are there in 125 ml. of a 5 M solution of sodium hydroxide?
A. 0.625 mol
B. 1.625 mol
C. 6.25 mol
D. 16.25 mol
One mole of sodium hydroxide equals 40g. dissolved in 1 liter of solution. A 5 M (molar) solution would be 5 X 40 g. of sodium hydroxide dissolved in 1 liter of solution. Therefore, 125 mil. of this solution would contain (125 X 5 X 40) / 1,000 of sodium hydroxide. Now divide (125 X 5 X 40)g. / 1,000 by 40 g./mole. to come up with the answer of 0.625 mole.