• Question: how is thermochromism made?

    Asked by thefemaleboss26 to Amy, Karen, Sarah, Vijay, Will on 15 Jun 2012.
    • Photo: Will Reynolds

      Will Reynolds answered on 15 Jun 2012:

      The thefemaleboss26. Fantastic question! I made some thermochromic molecules for my degree project. Thermochromism is when a material changes colour when heated or cooled and it is reversible so you can switch between two different colours just by varying temperature. White light is made up of lots of different colours that all have different energies. To generate colour a molecule has to be able to absorb some of this energy. The most common way of making thermochromism is to have a molecule that does not absorb any light energy (so it is colourless) and then when it is heated it changes shape so that the new molecule is able to absorb light and produces a colour. Similar to thermochromism there is also photochromism which is when a colour is generated by shining UV light on a molecule. Thanks for your question.

    • Photo: Karen Reed

      Karen Reed answered on 15 Jun 2012:

      Hiya – brilliant question but I’d have to ask what’s a thermochromism? Ah I see Will knows this one 🙂
      Its something that changes colour with temerature – I’ve got a ring like that.
      I was under the impression my ring had lots of different chemicals in it, each one gives out just one colour (which is different to the others) at a certain temperature. So if my hand is cold then molecule X in my ring gives me a purple colour, when my hand is warm molecule X no longer looks purple (its colourless) but molecult Y looks blue while when my hand is really hot molecules X and Y are colourless but Z now looks purple. So my ring changes colour with temperature that.

    • Photo: Sarah Martin

      Sarah Martin answered on 17 Jun 2012:

      Hi thefemaleboss26! Yes, I had a ring like that, and it said on the pack that it could tell you whether you’re in love or not! Will and Karen have covered the chemistry, so I’ll throw some biology in the mix. The theory goes that, when you’re in love, your body goes into overdrive – you can’t stop thinking about the person, you can’t sleep, and you’re constantly alert in case you see them. That takes a lot of energy, so your blood pressure increases (medically speaking, you’re stressed!) and so does your blood supply to your fingers and skin (making you blush easily), and making your skin warmer than usual, which a thermochromic ring would pick up.
      However I have tested this, and it doesn’t work well at all in cases when
      – it’s really really cold outside and you’ve forgotten your gloves
      – you’re in a swimming pool!

      Have you got thermochromic jewellery?

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