Question

The molality of 40percent NaOH w/w is

Answer 1

As % by wt of NaOH is 40 it's given wt is also 40 gm.
then let's consider water as solvent then it's wt will be 100- 40 gm = 60 gm
no. of moles of NaOH =given wt / molecular wt hence m= 40/40= 1 mole
molality = no. of moles of solute / wt of solvent in kg
so first let's convert wt of water solvent in kg =60 / 1000
molality =no. of moles /wt of solvent in kg
m=1 mole / 60* 10^-3 kg
henc molality =1*1000/60= 16.7

Answer 2

•Answer:16.67

•Explanation:

Let us assume the weight of NaOH to be 100 g

40%NaOH means 40 g of NaOH

Moles of NaOH are 40/40=1

Weight of solvent is 100-40=60g

m = 1/(60/1000)

   = 1000/60

   = 50/3

   = 16.67