Question

what will be the molality of 20% (w/v) solution of NaOH (density= 1.2 g/ml​

Answer 1

Answer:

Molality = 0.005m

Explanation:

Given-:

20%(w/v) means 20 g solute into 100ml solution.

Density= 1.2g/ml

To find-:

Molality=?

Solution-:

Density= Mass/Volume

1.2g/ml= Mass/100ml

Mass of solution=120g

According to question

Mass of solute(NaOH)=20g

And

Mass of solvent= 120-20=100g

Now,

No. of moles = Given weight/molar

of NaOH weight

No. of moles of NaOH = 20/40

No. of moles of NaOH = 0.5 moles

Now,

Molality= No. of moles of solute/

mass of solvent

Molality= 0.5/100

Molality= 0.005 m