Multiply 1.00 mL of ethanol by its given density of 0.789 g/ml and you get 0.789 grams. The molar mass of ethanol is 46 grams per mole. Divide 0.789 by 46 and you get 0.0172 moles of ethanol. Apply avogadro's law whihc is 6.023 x 10^23 molecules per mole of substance and you will get 1.033 x 10^22 molecules of ethanol
