Question

7.45 g of potassium chloride is dissolved in 100g of water what will be the MOLALITY of the solution.

Answer 1

molality=moles of solute (n) /weight of the solute (W)

No of moles of the solute = weight of the solute/molar mass

Molar mass of kcl=39+35.5=74.5
where,
atomic weight of K=39
atomic weight of Cl=35.5


no. of moles of KCl=7.45/74.5=0.1

molality =0.1/0.1
=1 mol/kg

Answer 2

1 mole kg^-1

Given:

Mass of the solute = 7.45 grams

Mass of the solvent = 100 grams - 0.1 kilograms

To Find:

Molality of the solution

Solving:

Calculating the molecular mass of KCl:

= 39 g x 1 + 35.5 g x 1

= 74.5 g mol^-1

Calculating moles of solute (KCl):

= Given Mass / Molecular Mass

= 7.45g / 74.5 g mol^-1

= 0.1 mole

Calculating the Molality of the solution:

= No of moles of solute / Mass of solvent in kg

= 0.1 mole / 0.1 kg

= 1 mole kg^-1

Therefore, the molality of the solution is 1 mole kg^-1 or 1 meter.