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Question
Define Molality.
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Solution
Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as:
Molality (m) = `"Moles of solute"/"Mass of solvent in Kg"`
Therefore, the unit of molality is mole per kg (mol kg−1).
If nB moles of solute are dissolved in W grams of solvent, then
Molality = `"n"_"B"/"W" xx 1000`
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