Why does an organic mixture being distilled using steam distillation never rise above 100 degrees Celsius?

100 degrees C is the heat coming in. Water will stay at 100, boil, evaporate to steam, etc but the temperature will stay 100 until all of the water is gone. Steam distillation is not why it doesn't go above 100. Its the boiling point of water. Stick a Bunsen burner under the water and it still will not go above 100 UNTIL all of the water is gone.

To understand why an organic mixture being distilled using steam distillation never rises above 100 degrees Celsius, we need to look at the principles of vapor-liquid equilibrium and the properties of water.

Steam distillation involves the use of water vapor to carry organic compounds from the mixture being distilled. The water vapor acts as a carrier or solvent, aiding in the separation of the organic compounds.

At atmospheric pressure, the boiling point of pure water is 100 degrees Celsius. This temperature is often referred to as the normal boiling point. When water is heated to its boiling point, energy is added, causing the water to vaporize. The water molecules gain enough energy to overcome the intermolecular forces and transition from the liquid phase to the gas phase.

During steam distillation, the mixture containing the organic compounds is heated, and water is added to generate steam. As the steam passes through the mixture, it carries the volatile organic compounds along with it in the vapor phase. The organic compounds have lower boiling points than water, which allows them to vaporize and be carried away by the steam.

Since the boiling point of water remains constant at 100 degrees Celsius, the maximum temperature reached during steam distillation is limited to this value. Any additional energy applied to the system will only cause more water to vaporize, but the temperature will stay constant as long as both water and vapor are present.

Therefore, the organic mixture being distilled using steam distillation does not rise above 100 degrees Celsius because the presence of water prevents the temperature from exceeding the boiling point of water, even with additional energy input. It ensures that only the volatile organic compounds are carried away with the water vapor, leaving behind the non-volatile components.