Graphically prove that T_(b) is greater than T_(b) ^(@).

1.	Graphically prove that T_(b) is greater than T_(b) ^(@).
Answer» Solution :(i) The vapour pressure of the solution increases with INCREASE in temperature. The variation of vapoup pressure with respect to temperature of pure water is given by the curv-A. (ii) At `100^(@)C,` the vapour pressure of water is equal to 1 atm. Hence, the boiling point of water is `100^(@)C(T _(b) ^(@)).` (iii) When a SOLUTE is added to water, the vapour pressure of the reslultant solution is lowered. The variation of vapour pressure with respect to temperature for the solution is given by curve-B. (iv) From the GRAPH, it is evident that the vapour pressure of the solution is equal to 1 atm. pressure at the temperature `T _(b)` which is greater than `T_(b) ^(@).` The difference between these TWO temperatures `(T_(b)-T_(b)^(@))` GIVES the evavation of boiling point. `DeltaT_(b) = T_(b) - T_(b) ^(@).`

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