Question

7.45gr of potassium chloride (KCl) was dissolved in 100g of water. Calculate the molality of the solution

Answer 1

Given:-

→ Mass of KCl (solute) = 7.45g

→ Mass of water (solvent) = 100g

To find:-

→ Molality of the solution

Solution:-

• Molar mass of Potassium (K) = 39g

• Molar mass of Chlorine (Cl) = 35.5g

Thus, molar mass of KCl :-

= 39 + 35.5

= 74.5 g

Number of moles in 7.45g of KCl :-

= Given mass/Molar mass

= 7.45/74.5

= 0.1 mole

Hence, 0.1 mole is present in 7.45g of KCl.

Now, let's convert the mass of water

from g to kg.

=> 1g = 0.001kg

=> 100g = 100(0.001)

=> 0.1 kg

Molality of a solution :-

= Moles of solute/Mass of solvent in kg

= 0.1/0.1

= 1 m

Thus, molality of the solution is 1 m .