Question

the molarity and molarity of 20%(w / w) sodium hydroxide solution respectively are ( density of solution is 1.2g/mL)

Please answer this question ​

Answer 1

Let x be the mass of solution.

Mass of NaOH=100x×20

Molar mass of NaOH=40g

∴ Number of moles= (10020x)/40=200x

Now mass of solvent in the solution= x−10020x=10080x

∴ Molality= (80x/100)x/200×1000=6.25M

Answer 2

Answer:

Let x be the mass of solution.

Mass of NaOH=100x×20

Molar mass of NaOH=40g

∴ Number of moles= (10020x)/40=200x

Now mass of solvent in the solution= x−10020x=10080x

∴ Molality= (80x/100)x/200×1000=6.25M