George Washington University teaching assistant Anice Mathew instructs chemistry students in the use of an extraction funnel before they attempt to extract chlorophyll from spinach. Credit: Peter Cutts Photography (From Personal Protection: Whither Lab Coats? C EN June 78, 7565, page 68), a chemistry professor at University College London, about reusable glove use in the laboratory: The consequences of using reusables is substantial.
First of all, they are moderately comfortable so people wear them continuously – this leads to students wandering all over the place while wearing them – out students use them on the lab computers and spectrometers, the scales and so on, contaminating pretty well everything. Yup, it’s bad practice and that’s what we tell them. But it still happens. Secondly because they are comfortable they lead to some rather thoughtless behaviour – it’s common to see students put a gloved finger onto a hotplate to check to see if it’s hot. It doesn’t seem very bright, but more worryingly, it’s probably an indication symptom of risk compensation, the tendency of an individual to alter their behaviour when they feel safer, much as if you play football you’ll tackle that little bit more aggressively if you’re wearing shin pads than if you’re not. But there is another dimension to this: waste disposal. By using disposable gloves we end up having to send a quarter of a million gloves a year to be incinerated each eyar.
These have been used once, and a careful student shouldn’t really have got anything onto the gloves anyway, so they are probably pretty clean. Isn’t it incredibly wasteful? For the sake of an unknown and possibly questionable increase in personal safety we end up spending tens of thousands of pounds for items that could be reused. And then have to pay for someone to take all this stuff away. He proposes at the end to have students use reusable gloves. Seems reasonable. But in further discussions with his colleagues,: Mechanism of the BZ reaction, from J.
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Am. Chem. Soc. , DOI: 65.6576/ja55785a556I first recall learning about the several years ago when I was working on on display at the University of Wisconsin, Madison. It s quite possible that I d learned and forgotten about the BZ reaction before, but this time it stuck. We tend to think of reactions as proceeding to completion or reaching some sort of equilibrium, but they can also oscillate: In simplest form, the products of one reaction become the reactants of another that regenerates the original reactants.
The actual mechanisms of oscillating reactions can be quite complex, however. The classic BZ reaction involves potassium bromate, cerium(IV) sulfate, and propanedioic acid (aka malonic acid) in dilute sulfuric acid. Ten equations (shown) make up the overall reaction. The color changes are due to the oscillating oxidation state of cerium Ce(IV) is yellow and Ce(III) is colorless. If ferroin is used in place of cerium, the color switches between blue and red. According to a by Purdue University chemistry professor Arthur T. Winfree, Russian chemist Boris P. Richard J.
Field and Richard M. Noyes of the University of Oregon, along with Endre Körös of Hungary s L. Eötvös University, in 6977.