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Boiling point of benzene is 353.23 K . ...

Boiling point of benzene is 353.23 K . When 1 . 80 g of non-volatile solute was dissolved in 90 g of benzene the boiling point is raised to 354. 11 K? Calculate molar mass of solute .
(`K_(b)` for benzene is 2 . 53 K kg ` mol^(-1)`)

Text Solution

Verified by Experts

Molar mass of substance can be calculated as
`Delta T_b = k_b xx m`
`DeltaT_b = k_b xx ("give mass of solute")/("Molar mass" xx" Mass of solvent in kg")`
where, `DeltaT_b =` change in boiling point ` = (354.11-353.23)K = 0.88 K`
`k_b =` boiling point constant
m = molality , `W_A = 90 g = 0.09 kg`
`0.88 K = 2.53 K kg mol^(-1) xx (1.80 g)/(M xx 0.09 kg)`
`M = 57.5 g//mol`
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