After fielding questions from students about what chemicals are in matches this week, it seemed like a good topic for a post looking at the question in more detail. When using matches on a day-to-day basis, you probably don’t think much of the chemical composition, or the reactions that are being set off; this graphic takes a look at some of the chemicals you can find in your average safety match, and the role they play.
There are a wide range of gemstones used in jewellery, with each having its own characteristic colour – or, in some cases, a range of colours. The origin of these colours has a chemical basis, and the precise colour can vary depending on the chemical composition of the gemstone. Interestingly, many minerals are actually colourless in their pure form, and it is the inclusion of impurities in their structure which leads to their colouration.
The latest in the Colourful Chemistry series looks at the inorganic compounds that give many paints their colours. This shows a limited selection of the most common compounds, and there are many others; there are also a large range of organic based pigments, which aren’t discussed here (although could possibly be the topic for a future graphic).
A previous post looked at the colours of transition metals, and the origin of their colours – this graphic, on the other hand, looks at how transition metals (and some non-transition metals) can be identified by the precipitates they form with sodium hydroxide and ammonia solutions. I’m going to keep the explanation of the reasons for the colour changes and precipitates fairly simple here, but I’ve provided links at the bottom of the page if you want to read about them in more detail.
This graphic looks at the colours of transition metal ions when they are in aqueous solution (in water), and also looks at the reason why we see coloured compounds and complexes for transition metals. This helps explain, for example, why rust (iron oxide) is an orange colour, and why the Statue of Liberty, made of copper, is no longer the shiny, metallic orange of copper, but a pale green colour given by the compound copper carbonate.
This graphic looks at the colour of various metal and metalloid ions that occur during flame tests. Most people probably remember doing this experiment in school chemistry lessons, if not with the full range of ions shown here, but, for the uninitiated, a brief explanation of the origin of the colours follows.
