Tag Archives: ice

Creative Science with Ice, Salt and Colour

Science Play  Ice Salt and Colour

This week we played with salt, ice and liquid watercolours.  It was one of those cool activities that combines science and creativity, and has everyone happily engaged for hours.

What You Need

  • One or more plastic containers – we used several, of different shapes and sizes. Ours had lids to make them easier to stack in the freezer.
  • Water
  • Salt
  • Liquid watercolours or food colouring
  • Plastic pipettes
  • Tray or dish to stand your melting ice in

science fun with salt ice and liquid watercolour

What We Did

I filled the containers with water and left them in the freezer for a couple of days.

We talked about the ways ice melts. The children said heat melts ice, so our ice would eventually melt if we left it out of the freezer. Or we could speed up the melting process by pouring on warm water. I asked them how we deal with icy paths in winter and they shouted “salt!”. We recalled how we added salt to ice to quickly freeze juice into a sorbet, and how that worked because the presence of an impurity (like salt) lowers the freezing point of water.

Then I handed over the salt and the liquid watercolours and let the children experiment.

They started out by sprinkling salt on the ice and noticing how the salt melted the ice where it came into contact with it. (Actually they started out by licking the ice – they do like to engage all their senses…  I made sure this happened only the once, before any salt or paint had been introduced!)

science fun with salt ice and liquid watercolour
Well it was probably good for his sensory processing!

Then C(9) had the idea of colouring her salt before sprinkling it on so she could follow its path. But she found the salt difficult to sprinkle when wet, so she decided to sprinkle and then quickly add colour. Soon she realised that she didn’t have to be so quick, because the colour always followed the path of the melting ice.

Fun with salt ice and liquid watercolour

More colours were added…

science fun with salt ice and liquid watercolour

science fun with salt ice and liquid watercolour

And great fun was had by all!

science fun with salt ice and liquid watercolour
Delicately does it

I loved seeing how differently each child interacted with their ice.  While C(9) enthused poetically about “glistening cataracts”, J(8) wore his best would-be world-dominating mad scientist expression as he attacked his with three purple pipettes at a time, shouting “I’m going to burn a hole RIGHT THROUGH THE HEART of it!”

Salty icy tunnel

Lots of creative expression, and some science too!

science fun with salt ice and liquid watercolour


Using food colouring instead of liquid watercolour – I think I added too much water to our liquid watercolours – they were a bit wishy washy (not that the children noticed). While they were busy making cataracts and chasms, I privately experimented with using gel food colours instead. These highlighted the paths of the melting ice much more clearly, but one drop went a long way so the children wouldn’t have had nearly as much fun if we’d used these – their ice would quickly have been saturated with colour. The vibrant colours make for quite a cool demonstration, though.

Gel food colour salt and ice
Gel food colour, salt & ice

Another scientific variation would be to experiment with different types of salt – rock salt, for example.

Science play ice salt and colour

Further Resources

Our arty science project was inspired by The Artful Parent.

Ice Tunnels: Bring on the summer fun! I found this after we played with our ice.

I hope you enjoy playing with colourful salty ice as much as we did!


Science Sunday

Collage Friday

Science Fun with salt and ice

Weekly Wrap Up at Weird Unsocialized Homeschoolers

homeschoolreview at hammock tracks

 Hobbies & Handicrafts

Edible Science With Ice And Salt

hands-on experiment salt and ice heat transfer

Here’s how you can make a tasty sorbet in five minutes while learning about the effect of freezing point depression with ice and salt.

C(9) found the experiment in our Science Experiments book. We had all the supplies so we were ready for some spontaneous learning fun!

hands-on experiment salt and ice heat transfer

What You Need

  • Orange juice (or other juice)
  • Crushed ice (or snow)
  • Salt (about 4 tablespoons)
  • 2 ziplock bags, one larger than the other
  • warm gloves

What You Do

1. Pour orange juice into the smaller ziplock bag.  Squeeze out excess air and seal.

hands-on experiment salt and ice heat transfer
2. Place the bag inside the larger ziplock bag.
3. Fill the larger bag with crushed ice so that it surrounds the orange juice bag.
hands on experiment with ice and salt
4. Add salt to the ice. The book suggests 4 tbsp but we just sprinkled liberally.
hands-on experiment salt and ice heat transfer
5. Squeeze out excess air and seal the large bag containing everything.
6. Gently massage the bag so that the salty ice is constantly coming into contact with the orange juice bag.
hands-on experiment salt and ice heat transfer
7. Continue squishing for 5-10 minutes, observing the changes in how the orange juice looks and feels.
hands-on experiment salt and ice heat transfer
ice and salt experiment

What Happens

The orange juice gradually solidifies and turns into sorbet!

hands-on experiment salt and ice heat transfer

The Scientific Explanation

Adding an impurity (salt) to ice lowers its freezing point. The ice wants to melt back to water, but to do this it needs to absorb heat from somewhere – in this case, the orange juice. Heat is transferred from the orange juice to the ice, freezing the orange juice.

This is an endothermic process (heat is absorbed).

For a detailed molecular explanation of why salt melts ice, see this article.

What We Might Try Next Time

We ended up with a very healthy snack, but for a treat we might make a sweeter sorbet by adding sugar. (Here are the ingredients for a simple lemon sorbet, and a whole list of delicious sorbets here – courgette (zucchini) sorbet looks interesting!)  We might even try making ice cream in a bag.

hands-on experiment salt and ice heat transfer

Further Resources

Why Does Salt Melt Ice?

An “Ice Energy” lesson plan (includes ice cream recipes)

Science Experiments: Loads of Explosively Fun Experiments You Can Do

Science Experiments Robert Winston


For more hands-on learning fun, head over to Hobbies & Handicrafts  at Highhill Homeschool, Homeschool Review at Hammock Tracks, and Science Sunday at Adventures in Mommydom.

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