Here at Science Space we think that a chemical garden is the closest the to magic you can get in science.
Watching tendrils of coloured crystals sprout and grow up towards the surface of the liquid in the flask is almost hypnotic. At least, that’s how we felt the Friday we started growing ours.
Here’s a timelapse of the experiment (and NO the footage has absolutely not been sped up – they really do grow that fast!):
So what’s going on? How does it work?
Well it’s all to do with density. The slightly cloudy liquid in the flask is a combination of a gel-like chemical called sodium silicate, and water. If you add coloured crystals of metals from the middle of the periodic table, transition metals like copper, nickel or cobalt, the surface of those metal crystals starts reacting with the silicate. This forms a kind of coating across the surface that’s less dense than the surrounding liquid.
Think about mixing oil and water – which one floats to the top? The oil is less dense than water so it floats. It’s the same with the metal coating – it wants to float. The crystals start to push their way up towards the surface and they look like they’re actually growing.
How cool is that?!
Here’s a video from the brilliant YouTube channel “Periodic Videos” with a fantastic explanation of the Chemistry behind the Chemical Garden. Check it out and make sure you come down to Science Space to see our version for yourself!