Question

What is the mass/ vol% ethanol in an ethanol water solution with density of 0.875g/ml and containing 65% ethanol by volume? The density of pure ethanol is 0.789g/ml?

My calculation
0.875g/ml x 1000ml x 0.65/ 46.06 = 12.34m
12.34/0.789g = 15.6g I am not sure answer. Pls help

Answer 1

I would consider this.
If the solution is 65% by volume EtOH, then in 1 L soln there are 650 mL EtOH. Since mass = volume x density, then the mass of EtOH in the L is 650 mL x 0.789 g/mL = 512.9 g.
Then (512.9/1000)*100 = 51.3% w/v.