Question

At room temperature , the density of water is 1 g/ml and the density of ethanol is 0.789 g/ml . What volume of ethanol contains the same no. of molecules as are present in 175 ml of water?

Answer 1

density H2O = mass x volume.
1.00 g/mL = mass x 175 mL
mass 175 mL = 175 grams.
mols in 175 g = 175/molar mass H2O = ?
no molecules = ? mols x 6.02E23 = ?

no molecules ethanol = same as H2O as ?.
mols ethanol = #molecules/6.02E23 = ?
grams ethanol = mols ethanol x molar mass ethanol
Then density ethanol = mass x volume. You know mass and density, solve for volume.

Answer 2

0.001766444ml

Answer 3

566.82ml