What mass of ethane (CH3CH3) is contained in 50.0 mL of a 13.9% by mass solution of ethane in hexane?

The density of the solution is 0.611 g/mL.

Mass of ethane which is contained in 50 mL is 4.25 g

Explanation:

13.9% by mass, means that in 100 g of solution, we have 13.9 grams of solute.

Density of solution is 0.611 g/mL

Volume of solution is 50 mL

Density = mass of solution / 50mL

0.611 g/mL. 50 mL = mass of solution → 30.55 g

Now, the rule of three.

In 100 grams of solution we have 13.9 grams of solute

30.5 grams of solution we have (30.55. 13.9) / 100 = 4.25 g