Question

why boiling point in condensate/distillate is less than original

Answer 1

In steam distillation, an immiscible mixture of water and an organic liquid is heated. The total vapor pressure of the system ($P_{total}$) is the sum of the partial vapor pressures of water ($P_{water}$) and the organic liquid ($P_{organic}$), i.e., $P_{total} = P_{water} + P_{organic}$. This mixture boils when $P_{total}$ equals the atmospheric pressure. Since both components contribute to the total vapor pressure, the mixture achieves atmospheric pressure and boils at a temperature lower than the boiling point of either pure component. The condensate/distillate is this mixture, therefore its boiling temperature is less than the boiling point of the original pure organic liquid.

Answer 2

The boiling point in the condensate/distillate is less than the original (pure organic liquid's boiling point) because, in steam distillation, the mixture of immiscible liquids (water and organic compound) boils at a temperature where the sum of their individual vapor pressures equals the atmospheric pressure. This temperature is lower than the boiling point of either pure component.