• Question: What would happen if you put water on Sodium?

    Asked by ellie789 to Daniel, Jon, Louise, Sharon, Zoe on 22 Jun 2010 in Categories: .
    • Photo: Sharon Sneddon

      Sharon Sneddon answered on 22 Jun 2010:

      It’s a great experiment to do, you should ask your teachers if they will show you it in class.

      In short, it will cause an explosion!

      Sodium is a very reactive metal, and if you place small amounts of soduim in water, it reacts with the oxygen in the water to make sodium oxide. Sodium will also react with water to make sodium hydroxide base and hydrogen gas. The reaction is exothermic enough to cause the flammable hydrogen gas to ignite explosively with oxygen in the atmosphere to make new water molecules.

    • Photo: Louise Dash

      Louise Dash answered on 22 Jun 2010:

      I’d stand well back if you were to try this!

      Usually we put sodium in water to demonstrate how it reacts (violently!), I imagine it would work the same the other way round.

      Here’s a video of it that I hope you can see through your school firewall (if not, watch from home later!)

    • Photo: Jon Copley

      Jon Copley answered on 22 Jun 2010:

      You get an explosion! One of my favourite experiments at school was throwing a chunk of sodium into a swimming pool (and the same thing happens with potassium too). The “alkali metals” in the periodic table, like sodium and potassium, are highly reactive.

      And that’s what the explosion is – a “strongly exothermic reaction”, as chemists would say. The reaction combines the sodium with the hydrogen and oxygen in water to form sodium hydroxide and hydrogen gas, and you get a lot of energy released as heat as well. This heat actually melts any remaining sodium that has not reacted yet, and ignites the hydrogen gas, so you get the bang and the flash.

      Here are some nice photos of the experiment:

      http://www2.uni-siegen.de/~pci/versuche/english/v44-1-1.html

    • Photo: Zoe Duck

      Zoe Duck answered on 22 Jun 2010:

      You would get a quite bit of fizz, possibly the sodium might move across the surface of the water pretty fast too. The sodium would react with the water to produce sodium hydroxide and release hydrogen gas. We did this experiment at school, ask you teacher if you want to see it, its quite exciting.

      If you look down the first column of the periodic table, each of those metals reacts with water in the same way, but the further down you go, the more reactive the metal so the ones at the end, caesium, rubidium and francium you get a pretty mighty explosion.

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