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Colourful Chemistry General Chemistry

What links litmus paper and lichens?

Along with universal indicator, litmus paper is one of the most commonly encountered pH indicators in school chemistry lessons. Unlike the range of colours produced by the former, litmus is pink-red in acidic solutions and blue in alkaline solutions. This graphic highlights its complex origins in lichens and the chemical changes that account for its […]

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Christmas Chemistry Colourful Chemistry

The Chemistry of Poinsettia Plants

Following on from the start of the Chemistry Advent Calendar yesterday, here’s another festive post, this time looking at the chemistry of the poinsettia plant. The red leaves of the poinsettia plant can be used to make a pH indicator, due to their chemical composition; this is actually something of an upgrade on one of the […]

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Colourful Chemistry

‘Poisonous’ Poinsettia pH Indicators

I’m making pH indicator paper with some of my classes this week, using the coloured leaves of red poinsettia plants, which set me thinking about the chemistry behind why these plants can be used as indicators. Poinsettias have a reputation for being poisonous – a claim that is in fact entirely unfounded. A quick google […]