Question

Calculate molality of 10% NaOH by mass(w/w).

Answer 1

Explanation:

10%NaOH means 10g of NaOH in 100g soln.

weight of solvent = weight of soln.- weight of solute

=100-10=90g

given mass of NaOH= 10g

Molar mass of NaOH=40g mol^-1

no. of moles of NaOH=

given mass/molar mass

=10/40

=2.5 mol

molality =

no.of moles of NaOH/wt of solvent(in kg)

=2.5*1000/90

=2500/90

=27.77m

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