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  

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l