Which is the most correct way to determine moles?

[gammagirl]

I used 3 mL of 95% ethanol? 3mL x 0.789/ml x mol/46.068 g = 0.0513gm OR 95gm/100ml =x/3ml, x= 2.85 gm ethanol x mol/46.068 g= 0.06187 gm

[hypervalent_iodine]

Neither. I believe that the 95% is v/v% not w/v. The density value you have is of absolute ethanol also, not 95%. 

[gammagirl]

Both are good points. Thank-you