Molality Formula

Molality Formula

The number of gram Mole of the solute present in the 1000 g or 1 kg of the solvent is known as molality of the solution.

  • Molality is denoted by ‘m’.
  • Unit of molality is mol/ kg
  • Molality does not affect by temperature.

Formula :

m = molality

n  = number of Mole of solute

w = Mass of solvent in kg

  • The volume of solution given in mL that the formula will be following.

Question:

Calculate the molality of the solution containing 20.7 g of K2CO3 dissolved in 500 mL of solution?

Solution:

solution = solvent + solute

500 = solvent + 20.7

solvent = 500 – 20.7

Solvent = 479.3 g

Molar mass of K2CO3 = 138

Molar mass of K2CO3 = (given mass)/(molar mass)

Molar mass of K2CO3 = 20.7/138 = 0.15 mol

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