Question

Calculate the molality of a solution formed by adding 6.30 g NH4CL to 15.7 g of water

Answer 1

Answer:

Molality = 7.5 mol/kg

Explanation:

Given data:

Mass of NH₄Cl = 6.30 g

Mass of water = 15.7 g (15.7/1000 =0.016 kg)

Molality = ?

Solution:

Formula of molality:

Molality = Moles of solute / mass of solvent in gram

Now we will first calculate the number of moles of solute( NH₄Cl )

Number of moles = mass/ molar mass

Molar mass of  NH₄Cl = 53.491 g/mol

Number of moles = 6.30 g/  53.491 g/mol

Number of moles =  0.12 mol

Now we will calculate the molality.

Molality = Moles of solute / mass of solvent in gram

Molality =  0.12 mol / 0.016 kg

Molality = 7.5 m

or        (m=mol/kg)

Molality = 7.5 mol/kg