Question

10 g of nh4cl is added to 12.7 g of water. calculate the molality of the solution.

Answer 1

Molality of the solution is defined as Number of moles of solute present in 1 Kg of solvent.

Mathematical it can be represented as:

m=n/ mass of solvent(Kg)

m=Molality of the solution,

n=Number of moles of solute

Here as it is given 10 g of NH4Cl and Molar mass of NH4Cl=53.491 g/mol

Number of moles of NH4Cl:

=Weight of solute/Molar mass of solute

=10/53.491

=0.186

Mass of solvent=Mass of water =12.7 g

So molality:

=number of moles of NH4Cl/ mass of water(Kg)

=0.186*1000/12.7

=14.7m