• Question: Is water wet?

    Asked by Fragle10209 to Alan, Ciorsdaidh, Lauren, Leonie, Martin, Neil, Shuo on 9 Mar 2018.
    • Photo: Lauren Webster

      Lauren Webster answered on 9 Mar 2018:

      Is water wet?? You already know what water is made up from, oxygen and hydrogen. Each one of the water molecules is surrounded by another water molecule and many more just like it, making up the liquid you can see, touch and even drink – known as water. But no where in there does it mention about being wet. Wet is a term that we have come up with to describe the sensation water gives us. When you touch water, what do you feel? When you drink the water, how does it feel? The answer, the term we have all given it…wet.

    • Photo: Alan McCue

      Alan McCue answered on 11 Mar 2018:

      In my area of chemistry the term ‘wet’ refers to whether or not a liquid spreads out on a solid as opposed to saying in a clump. To understand this imagine you have a water ballon and sit it on a kitchen work-top. Nothing happens so the ballon does not ‘wet’ the worktop. However, if I burst the ballon the water spreads out and ‘wets’ the surface. This depends on the liquid and the solid and is not a term specific to water… hope that makes some sense.

    • Photo: Martin McCoustra

      Martin McCoustra answered on 12 Mar 2018:

      Alan is correct. Like many scientific things we have a clear definition of what is wetting. As Alan says, water wets something when a droplet of water on the surface spreads out. It doesn’t wet when the droplet remains balled up. So to answer your question, we’d need to know what is the water interacting with?

    • Photo: Neil Keddie

      Neil Keddie answered on 13 Mar 2018:

      Water is definitely wet – but it depends on what it is trying to spread it out on. You can put all surfaces into one of two categories: hydrophobic, or hydrophilic.
      A hydrophobic surface is one that hates water, and make it bead on the surface and easily run off (think of a teflon frying pan, or a waterproof jacket or a car just after you have waxed it). The reason the water runs off, is that the surface is made up of molecules that are not like water at all, but more like oil (we know oil and water don’t mix), so the water does not like to interact with the surface.
      A hydrophilic surface is just the opposite – this is one where water likes to spread out. The water spreads, as the surface has groups on it like water (usually –OH groups), which allows it to make good interactions and spread.

      So the key question is, what are you trying to wet with your water…

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