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