What is the mole fraction of NaOH in an aqueous solution that contains 22.9% NaOH by mass?
Na=23
O=16
H= 1.01

The mole fraction of NaOH in an aqueous solution that contain 22.9% NaOH by mass=0.882

Explanation:

We are given that

Aqueous solution that contains 22.9% NaOH by mass means

22.9 g NaOH in 100 g solution.

Mass of NaOH(WB)=22.9 g

Mass of water =100-22.9=77.1

Na=23

O=16

H=1.01

Molar mass of NaOH(MB)=23+16+1.01=40.01

Number of moles =

Using the formula

Number of moles of  NaOH

Molar mass of water=16+2(1.01)=18.02g

Number of moles of water

Now, mole fraction of NaOH

=

=0.882

Hence, the mole fraction of NaOH in an aqueous solution that contain 22.9% NaOH by mass=0.882