Question

How would you separate into its different components (a) a mixture of the volatile gases propane, butane, and isopropane? (b) a solution of rubbing alcohol made up of isopropyl alcohol and water?

Short answer

Answer: The main methods used to separate the mixtures are fractional distillation for propane, butane, and isopropane, and simple distillation for the isopropyl alcohol and water solution of rubbing alcohol.

Step-by-step solution

Utilize Fractional Distillation

In order to separate these gaseous substances, we can use fractional distillation. This method involves heating the mixture while the gases slowly evaporate at different temperatures due to their different boiling points. The gas with the lowest boiling point will evaporate first followed by the others in ascending order of boiling points.

Collect Each Gas Separately

As each gas evaporates, it will rise up the column and condense, then it can be collected separately. The first gas that evaporates can be stored in its specific container. When the temperature reaches the boiling point of the second gas, it will begin rising up the column. Discontinue the collection of the first gas and start the collection of the second gas. Repeat the same process for the third gas. This will ensure that each gas has been separated and collected efficiently. (b) Separating isopropyl alcohol and water in a solution of rubbing alcohol

Simple Distillation

To separate isopropyl alcohol and water, we can use the process of simple distillation. This process relies on the fact that isopropyl alcohol and water have different boiling points, with isopropyl alcohol boiling at around 82.5°C and water boiling at 100°C. By heating the mixture, isopropyl alcohol will evaporate before the water.

Heat the Mixture and Collect the Distillate

Set up a simple distillation apparatus by placing a round bottom flask containing the rubbing alcohol solution on a heating mantle and connecting it to a condensation column and a collection flask. Start heating the mixture until the temperature reaches around 82.5°C. At this point, isopropyl alcohol will start evaporating and travel up the column, where it will condense and then flow into the collection flask.

Stop Collecting When Water Starts Evaporating

Monitor the temperature of the mixture. When it gets close to the boiling point of water (100°C), stop the heating process and discontinue the collection. This will ensure that only isopropyl alcohol has been collected, leaving the water in the original flask.