Interpretation:
With the help of mass of unknown compound, mass of water and the freezing point, molar mass of the unknown compound is to be calculated.
Concept introduction:
Molality is the number of moles of solute to the mass of solvent.
Relation between number of moles
To convert
The mass of the solvent should be in kilograms
Calculate molality as follows:
The temperature at which change of liquid state to solid state takes place is called freezing point.
The freezing point depression is as follows:
Here,
Molality of the solution in
Constant for the solvent.
For water:
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INTRODUCTORY CHEMISTRY-W/SEL.SOLN.MAN.
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