Running a practical exam with several staff invigilating highlights, very clearly, the differences in approach to certain lab techniques. For a reaction heated to reflux, do we clamp the flask, the flask and the condenser, or the flask but with a second clamp loose around the condenser for a little stability? Are disposable nitrile gloves good enough for this type of use or that type of use? Can syringes be used, without needles, to measure reasonably accurate quantities? Does the hotplate sit on the clamp stand base or is the clamp angled for the hotplate to sit to one side? Do we clamp buchner flasks during vacuum filtration or not? What about clamping conical flasks on the hotplate during recrystallisation? For the practical exam, I try to take the pragmatic approach of ‘has made desired product in a manner the invigilator regards as safe and effective’ but on several levels I think we’re confusing students. I particularly enjoy the sometimes ‘scientific’ rationale for various perspectives.
Are chemists actually capable of reaching a consensus on what is safe and what poses an undue hazard in the lab?
It must be very confusing for students who learn to do things one way in one class with one academic but a different way the next semester and so on. Who should they believe? Most of our students are capable chameleons: they modify their behaviour depending on who’s in the room (or who’s doing the marking). This means they’ll probably recall how they were taught by this person and do it that way. When they join a research group, chances are they’ll slowly slip in to the way of working they see around them. I wonder how many times the students are given a good explanation as to why they should or should not do things? And I wonder how often that’s based on reasonable evidence and safety rather than simply believing that one’s one way is the best?