We set up the experiments with the following parameters: Heating bath temperatureĪnd we tested three different solvents: water, ethanol and acetone using the Rotavapor® R-300. In fact, my colleagues have performed several experiments to demonstrate this and I’ll share the results with you now. It’s not the first time I discuss this topic, check out a previous blog post on condenser loading for more information.Īnother way to tackle loss of distillation rate when operating at lower heating bath temperatures is to increase size of your evaporation flask. A condenser is overloaded if condensate is observed downstream from the condenser or if the vacuum pump sucks continually to maintain a set pressure.
In this case, the top third acts as a safety barrier for “entrained” low boiling solvents and for pressure fluctuations. Optimal capacity occurs when two thirds of the condenser height is covered with condensate. In fact, you should make sure that the heating bath temperature, the pressure and the cooling temperature are adjusted to condenser’s capacity. Take the capacity of the condenser into account if you want to maximize the distillation rate while avoiding flooding of the pump at the same time. However, if you set the pressure too low, you can trigger re-evaporation of the solvent at room temperature, which loads the condenser with unnecessary vapor from the receiving flask. One approach to reducing the heating bath temperature without affecting the distillation rate is to adjust the pressure. There are ways to avoid working at temperatures exceeding 60☌, which I will discuss below. Additionally, it is dangerous to set the heating bath beyond a certain level, not to mention that it sucks up energy and money from the lab. However, thermo-sensitive samples should not be heated at high temperatures to protect some of their properties, for example flavours. Of course, going as high as possible seems to intuitively make sense.
In fact, there are three key points you should consider whenever you are trying to increase your distillation rate. Is using 90☌ heating temperature the most efficient and safest solution for achieving a high distillation rate? Understandably, we often try to achieve this by increasing the heating bath temperature. Just as a reminder, the distillation rate is a measure of the amount of clean solvent that can be obtained in a specific time period. Naturally, scientists performing distillations on their rotary evaporator want to achieve the highest distillation rates. It’s actually a battle to be fought in the lab as well. And speaking of her rice, I do not understand why she insists on letting it boil on high, when medium would have just the same effect, but cost us less money, reduce the risk of the rice burning and sticking to the bottom of the pot and do less damage to the pot! She always adds a bit more salt to my stew, I always turn down her boiling rice. After years of cooking side by side with my wife, we have still not resolved the battle of who the true iron chef is.