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Assuming complete dissociation, calculat...

Assuming complete dissociation, calculate the molality of an aqueous solution of KBr whose freezing point is `-2.95""^(@)C`. `K_f` for water is 1.86 K kg `mol^(-1)`

Text Solution

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`KBr=K^+` +`Br^(-)`
`i= ("moles of particles after dissociation")/("moles of particles dissolved")=2/1 = 2`
`DeltaT_f=iK_fm`
`DeltaT_f = 0 ""^(@)C- (-2.95 ""^(@)C) = 2.95 ""^(@)C`
`m = (DeltaT_f)/(iK_f) = (2.95 K)/(2 xx 1.86 Kkg mol^(-1))`
0.793 `mol kg^(-1)`
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