Question

Mole fraction of naoh in 5 molal aqueous naoh solution is

Answer 1

1 mole NaOH is equivalent to 40 gm of NaOH.

Molality can be defined as the number of moles of solute in 1000 gm of solution.

Thus 5 molal aqueous NaOH solution contains, [ (5 x 40) = 200 ] gm NaOH.  

Thus water present in the solution = (1000 - 200) = 800 gm

Moles of water present = (800 / 18) = 44.45

Thus the mole fraction of NaOH = (moles of NaOH / Total moles in solution) = (5 / 5 + 44.45) = 0.101