Categories
Biochemistry

Peonin and the colour of peonies

Peonies bloom fleetingly at the end of spring and start of summer, usually only lasting around 10 days. Inspired by this tweet from Dr Jess Wade, here’s a quick look at the molecule which gives them their colour. There’s more on the pH dependence of anthocyanin colour here.

Categories
Colourful Chemistry Food Chemistry

Making a Red Cabbage pH Indicator: The Method and the Chemistry

We all know examples of everyday substances that can be classified as acids or alkalis: lemon juice is acidic, bleach is alkaline, and so on. Another substance that can be found in your kitchen can be used to test other substances to determine whether they are acidic or alkaline. The chemicals that give red cabbage 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 […]

Categories
Colourful Chemistry

The Colours & Chemistry of pH Indicators

Most of us, chemists or otherwise, have probably come across pH indicators at one point or another. I’d be surprised if there’s anyone out there who hasn’t, back in school, carried out the standard experiment of adding universal indicator to a variety of household liquids to identify them as acidic or alkaline. You might not […]

Categories
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 […]