A Day in the Life of an Organic Chemist Quiz

Answer: round-bottom flask

A round-bottom flask is like a sphere of glass with a little neck in the top. They come in various sizes, ranging from as small as 5 ml all the way up to 2 L and more! Round-bottom flasks are really handy for carrying out chemical reactions, as their shape allows for efficient stirring of the reactants.

Answer: condenser

A condenser fits neatly into the top of a round-bottom flask and is a tube of glass surrounded by another glass tube that acts as a jacket for water to circulate. This water cools the vapour rising from the heated flask below, condensing it so that it falls back into the flask.

Answer: drying tube

A drying tube is a short tube of glass designed to hold some kind of desiccant (such as calcium chloride) and fits into the top of a condenser or even directly into the neck of a round-bottom flask. Although a drying tube will still, in theory, let air into a reaction set-up, because the air must pass through the desiccant first, it will be DRY air.

As long as none of your reagents are oxygen-sensitive, a drying tube is an excellent way of excluding water from reactions. Another way of doing this is by using a balloon of an inert gas (such as nitrogen) on the top of the condenser to exclude anything that may come from the atmosphere.

Answer: thin layer chromatography

Analytical thin layer chromatography (TLC) is a powerful tool for the synthetic chemist. A TLC plate is commonly a thin layer of adsorbent (such as silica) spread onto a solid support like a sheet of aluminium metal. TLC relies on the principle that different compounds will interact differently with the adsorbent and the solvent used to develop the thin layer chromatogram. All a chemist needs to do is drop a tiny spot of the solution (in this case, a reacting mixture) at the bottom of the plate next to a spot of a reference compound and develop the plate in an appropriate solvent.

The resulting chromatogram will indicate how the reaction is progressing (if at all!).

Answer: separating funnel

A separating funnel is your best bet whenever you've got a procedure that wants you to "extract" or "wash" something. A separating funnel is shaped a bit like an inverted tear-drop, with a neck at the top and a tap at the bottom. Separation of layers in separating funnels is possible because most organic liquids (solvents) are immiscible with aqueous (water-based) liquids. You'll usually see two layers in your separating funnel, one of which will contain your reaction product.

The best way to avoid throwing out the wrong layer by mistake is to label all layers that you remove from the separating funnel and don't throw anything away until you're holding what you want in your hand!

Answer: rotary evaporator

A rotary evaporator makes use of the fact that as the atmospheric pressure is reduced, so too is a solvent's boiling point. A round-bottom flask containing the solution to be concentrated is attached to a rotating column surrounded by a condenser coil and also attached to a vacuum.

The vacuum is turned on, and the motor starts spinning the flask. As the vacuum does its job and reduces the pressure inside the apparatus, the solvent will start to bubble off, often with the help of a warm water bath placed under the spinning flask.

The reduced pressure enables solvents with very high boiling points to be removed relatively easily and at a much lower temperature than would otherwise be required. A hotplate can, in theory, be used to remove solvents as well, but I wouldn't recommend it, as many organic solvents are flammable!

Answer: infrared spectrometer

Infrared spectroscopy (commonly shortened simply to "IR") is an excellent way of seeing what functional groups are present in a molecule. A sample of the compound to be studied is placed in a beam of infrared light whose wavelength is gradually changed over a set range.

The different energies of the range of wavelengths will cause different functional groups to stretch and bend their respective bonds. The response of the sample is measured and plotted out, giving a spectrum from which information on functional groups present in the molecule can be deduced.

Answer: conical (Erlenmeyer) flask

Recrystallisation is a quick and easy way of purifying solids and relies upon the fact that most compounds are more soluble in hot solvents than they are in cold solvents. Provided a suitable solvent can be found, all you need to do is add some of the appropriate HOT solvent bit by bit until all of the crude product is dissolved, then let it cool back down to room temperature and voila! Nice, pure crystals of product! Recrystallisations should ALWAYS be carried out in a conical flask for a number of reasons, such as: it is the most efficient vessel in which to keep the added recrystallisation solvent warm, it's much easier to swirl liquids in a conical flask and the fact that the walls of the conical flask act as a kind of condenser, ensuring that solvent loss through evaporation is reduced. Don't try and recrystallise something in a beaker - swirling hot solvent in a beaker is not a good idea!

Answer: Buchner funnel and Buchner flask

Buchner glassware is what is used to collect solid products. The funnel is usually made of porcelain or plastic and features a flat base punctured with lots of small holes over which a piece of filter paper is placed. The Buchner flask is attached to a vacuum source and the contents of the recrystallisation flask are poured into the funnel.

The liquid passes through the filter paper, leaving the pure crystals on top. A filter funnel and conical flask can give you the same basic effect, but are almost always used for removing solid impurities you don't want from a solution, rather than for collecting a solid reaction product.

Answer: nuclear magnetic resonance (NMR) spectrometer

Nuclear magnetic resonance (NMR) spectroscopy is such a vital tool for any synthetic chemist that it's hard to believe it has only been around in its present form since the early 1950s, when the first commercial NMR spectrometer was introduced. NMR spectroscopy relies on the fact that under certain conditions in a magnetic field, an atom's nucleus can absorb electromagnetic radiation at particular frequencies governed by the sample's characteristics.

A plot of this absorption versus the frequency range is what constitutes an NMR spectrum. NMR spectra can be run for the nuclei of hydrogen, carbon and nitrogen atoms to name just a few. And there you have it - the NMR spectrum of my product indicates that it's the right compound, so it's back up to the lab to clean up from the day's work and then home!