1.

Theboiling pointof anaqueoussolutionis 100.18.^(@)C. Find thefreezingpointof the solution . (Given: K_(b)= 0.52K kg mol^(-1),K_(f) = 1.86K kgmol^(-1))

Answer»


Solution :Given : `T_(b)=100.18.^(@)C +273= 373 .18 K`
`K_(o) =0.52 K kg MOL^(-1), K_(f) =1.86 K kg mol^(-1)`
Boiling point ofwater`= T_(o)= 373 K`
`T_(f)= ?`
`Delta T_(b)= T_(b) - T_(o) =373 . 18 - 373= 0.18 K`
If m is themolalityof thesolutionthen
`Delta T_(b)= K_(b ) XX m " and"Delta T_( f) = K_( f) xx m`
`:.(DeltaT_(f))/(Delta T_(b))= (K_(f) xx M)/(K_(b) xx M) = (K_(f))/(K_(b))`
`:.Delta T_(f) = Delta T _(b) xx .(K_(f))/(K_(b))= 0.18 xx .(1.86)/(0.52) =0.6438 K`
Freezingpoint ofwater = `T_(o)= 273 K`
`Delta T_(f) = T_(o)- T_(f)`
HENCETHE freezingpoint of thesolutionis
`T_(f)=T_(o)- Delta T_(f) =273-0.6438= 272. 3562 K`
ORFreezingpoint ofsolutionis - 0.6438 `.^(@)C`


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