Question

20% of naoh(w/w) solution is given.its molality is...

Answer 1

LET ASSUME mass of solution be "x " gram.

so,  mass of NaOH present in it = x * 20/100

Molar mass of NaOH= 40gram

So, number of moles of NaOh present in the solution = (20 * x/100) * 1/40 = x/200

solvent mass present in the solution = solution mass  -  solvent mass  = x-20x/100 =80x/100 (in grams)

So that molality of solution is (x/200)/( 80x/100) * 1000 =6.25