Question

I have a paint thinner that contains 60% toluene and 40% acetone. I would like to obtain some more-or-less pure toluene. Considering the big difference in boiling points (110°C toluene vs 56°C acetone), and because I only need the toluene and not the acetone, I just tried to pour the paint thinner in a pot and put it on the outside stove. What I expected to happen, based on my small understanding of chemistry, was that the temperature would rise until 56°C where it would stay for a while and bubble off all the acetone, and then to stop bubbling and the temperature to increase until 110°C where it would start to bubble again. However what really happened was that both the temperature never stopped rising and the liquid never really stopped bubbling once it had started (although it slowed down to some degree after the first 30 seconds or so). When I only had like 20% of the original amount left, I accepted I have no idea what I'm doing and took the pot off the stove. Does this whole procedure even make sense? And if yes, how should I approach it? Maybe try to keep the temperature precisely on a certain level?

Answer 1

The student's procedure of heating the paint thinner to separate toluene and acetone is not effective. Fractional distillation is a suitable method for separating the two substances based on their boiling points.

Step-by-step explanation:

The student's procedure of trying to separate the toluene and acetone by heating them is not effective because both substances have boiling points that are relatively close to each other. When the paint thinner was heated, both toluene and acetone would evaporate, resulting in a mixture of both vapors being released. Additionally, the bubbling observed is not an indication of the separation of the two substances but rather the release of vapors.

An effective method for this separation is a process called fractional distillation. This process takes advantage of the difference in boiling points between the two substances. By heating the mixture and collecting the evaporated vapors, one can separate the toluene from the acetone. This is done by using a fractionating column, which allows for the separation of components based on their boiling points.