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How is molar mass related to the elevati...

How is molar mass related to the elevation in boiling point of a solution ?

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To calculate the molar mass of an unknown non - volatile compound a known mass (say `W_(B)` g ) of it is dissolved in a known mass (say `W_(A)` g) of some suitable solvent and elevation in its boiling point `(Delta T_(b))` is determined . Let `M_(B)` be the molar mass of the compound . Then
Molality of solution m ` = (W_(B))/( M_(B)) xx (1000)/(W_(A))`
We know, ` Delta T_(b) = k_(b) xx m = K_(b) xx (W_(B))/( W_(A)) xx (1000)/( M_(B))`
` M_(B) = (K_(b) xx W_(b) xx 1000)/( W_(A) xx Delta T _(b))`
Knowing ` K_(b) , W_(B), W_(A) and Delta T_(b)` , the molar mass of the compound can be calculated from the above relation . This method is known as ebullioscopic method
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