Materials Investigators – Surface wetting

Does water behave the same on all surface?

The surface of a material controls lots of properties of a materials such as what it looks like, what it feels like and also how water (and other liquids) behave on it – just think about your raincoat, you wouldn’t want it to soak the water up would you?

This activity looks at how different solids change the way a water droplet behaves on the surface of a materials (in other words how a liquid wets the surface).We have prepared a worksheet (which can be downloaded here). We haven’t yet made a specific video for this activity but the section between ~7min20s and 14min30s on the following video is relevant: https://youtu.be/6S-M9ZyeqD0

Ideas for surfaces to look at

Examples

• Example 1: Waxy vs Glassy Surfaces

Try putting a water droplet on a waxy surface and a glass to compare them. What’s the difference between the droplets?

• Example 2: 

Try putting a water droplet on a cabbage leaf or a holly leaf. Each leaf is waxy so what is the different about the surfaces ?

Equipment needed

• ‘Materials Investigators – Surface wetting’ worksheet (downloadable from our website)
• Magnifying glass / microscope lens (e.g. clip-on microscope lens)
• Water dropper / pipette
• Water
• Pen / pencil
• Different materials to look at
• Tissue paper (to dry up spills)

Risks:

Cuts

• Broken glass may cause cuts, be careful handling glass objects

Slips

• Any spillages should be cleared immediately

Links:

Materials Investigators – Surfaces

Nature’s Raincoats (external site)