Final answer:
Fractional distillation shows more gradual temperature changes due to multiple vaporization-condensation cycles, whereas simple distillation involves a single such cycle resulting in more abrupt temperature changes.
Step-by-step explanation:
When comparing the temperature profiles of simple distillation versus fractional distillation, the changes in temperature occur more gradually in fractional distillation. This is because fractional distillation employs a column with trays or packing, which allows for multiple vaporization-condensation cycles as the mixture ascends the column.
During fractional distillation, the heated vapor rises and encounters cooler temperatures at each stage or tray. Since constituents in the mixture have different boiling points, the vapor will condense selectively, the highest boiling components first, and the lower boiling ones as they move up the column. This process results in a more gradual change in temperature over time, as well as a more efficient separation of the components.
In contrast, simple distillation involves a single vaporization-condensation process, leading to a quicker and more abrupt temperature change as the distillate is collected over a narrower boiling range, without the gradual separation offered by fractional distillation. The sharp temperature change reflects the direct transition from the boiling point of one component to the boiling point of the next.