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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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Chemistry History General Chemistry

Today in Chemistry History: Søren Sørensen and the pH scale

On this day (9th January) in 1868, Danish chemist Søren Sørensen was born. He’s best known for developing the pH scale, which we’ve likely all encountered, to measure the acidity or alkalinity of solutions. This graphic gives a brief overview of the pH scale and what it means.

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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.

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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 […]

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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 […]