Blue ruby

This post contains a collection of animated gifs and other pictures from experiments we have been doing recently.

First a heart made by putting copper foil into silver nitrate solution (copper is more reactive than silver and displaces silver ions from solution).

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Silver heart

Next, heating a beaker of ice to water and steam.

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Ice water steam

Those are anti-bumping granules you can see at the bottom of the beaker in the boiling water.

Now for a rather pretty B/Z reaction we carried out recently.

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A Belousov-Zhabotinsky reaction

Captured using time-lapse mode

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99 pictures at 15 seconds interval

Finally, the curious case of the colour of chromium (III) ions in water. And hence the title of this post ‘Blue ruby’.

When asked “How do you make a blue heart red?”
“With a torch and chromium (III) ions”, I said

Jim Clark, writing on Chemguide.co.uk notes that “The simplest ion that chromium forms in solution is the hexaaquachromium(III) ion – [Cr(H2O)6]3+.” He also goes onto say that “The hexaaquachromium(III) ion is a “difficult to describe” violet-blue-grey colour.”

Our AQA A’ level Chemistry describes [Cr(H2O)6]3+ as being ruby in colour, but our solution of chromium (III) chloride definitely looks blue to me.

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chromium (III) chloride solution

That is, until one looks at it under torchlight (tungsten filament bulb), then
indeed it does appear a ruby colour.

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blue or ruby?

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Use a torch

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shine a light

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then you’ll see ruby delight

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off on off

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has that boiling tube got a red eye?

 

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