Tag Archives: experiments

explosive experiments

My boys love experimenting with different liquids – making potions and lotions and explosions of all colours and kinds. This is no surprise to me as I loved doing it as a child too! I seem to recall my brothers and me making our mum some rank smelling perfume out of rose petals which we’d squelched underfoot and then squished into a bottle which we topped up with water and glitter. She must have been… thrilled?

Anyway, over the past few years, whenever a rainy weekend hits, the likelihood is, one of my boys will say “Let’s do an experiment!”. Once, they even decreed it “Harry Potter Day” and spent most of the afternoon making potions. When we first started experimenting, we tried a few we got out of a book but along the way we’ve often gone more free-style and have made all sorts of weird and wonderful concoctions, some of which I thought I’d share with you now. Make sure these are done under adult supervision!

Experiment one – the lava lamp

You will need: Vegetable oil, water, Alka-seltzer, food colouring, drinking glass, plate.

Experiment: Put the glass on a plate (you’ll see why later) pour vegetable oil into it until it is just under a half full. Add a similar amount of  vegetable oil. Wait for the oil and water to separate. Add some (maybe ten) drops of food colouring and wait for it to fall to the bottom. Then add an Alka-seltzer and watch the results! The coloured water rises up through the oil in bubbles and the colours swirl.

oil and water

Ok, so I couldn’t find a photo with food colouring in…not at this stage anyway…

The Science:

Stage 1 – Water is denser than oil so it sinks to the bottom and the oil sits on the top. Food colouring is also denser so it falls through the oil and into the water.

Stage 2 – when you add the Alka-seltzer it fizzes when it meet the water. This releases carbon dioxide which reduces the density of the water causing it to rise up and through the oil. When it reaches the top of the oil the carbon dioxide is released and the water sinks again.

Added bit of fun:

Remember the plate? you’ll need it if you follow the next bit which is my boys’ favourite bit of all – they add more and more Alka-seltzer and food colouring and the whole things bubbles up and runs down the side of the glass. It’s pretty impressive!

I don't normally show my boys faces on my blog but this is well over two years old so, meh.

“WE WANT IT TO EXPLODE!” (I don’t normally show my boys faces on my blog but this is well over two years old and they all look different now!) I love the expression on my youngest’s face!

Experiment two – the volcano

You will need: Plastic volcano (we got one with a kit) or a glass, bicarb of soda, vinegar, food colouring, that trusty plate again.

Experiment: Put the volcano or glass onto your trusty plate. Put the food colouring and bicarb of soda into the volcano (or glass). Are you ready? Pour on the vinegar! It froths and foams up and over and down the sides in a very impressive display!volcano experiment

The science:

Vinegar is a weak solution of acetic acid. Bicarb of soda is a base or alkali. When the two are mixed, a neutralisation reaction occurs which releases carbon dioxide. The carbon dioxide takes up more space than the bicarb of soda and vinegar hence the bubbling, fizzing, expanding potion!

Experiment three – fireworks

You will need: a large clear plastic (or glass) bowl, beaker, water, tablespoon of vegetable oil, food colouring, water, white paper.

Experiment: Put the plastic bowl on a table with the white paper behind it (a white backdrop makes it easier to see the ‘fireworks’ when they happen). Fill the bowl with water. Put a tablespoon of vegetable oil in a beaker and mix in a few drops of food colouring. Pour the mixture from the beaker into the bowl of water and watch the effects! The droplets of oil and food colouring float to the surface of the water. Once they reach the surface they explode and sink down like a firework display.

fireworks in a bowl

View from above – personally I liked this view best!

fireworks in a bowl 2

View from the side

The science:

Water is more dense than oil, so the oil and water floats to the surface. When it reaches the surface it bursts and the colouring floats back down, dissolving in the water and causing the colour effects.

Experiment four – floating egg FREESTYLE!

As I wrote at the start, my boys love to experiment, so this was one my six-year-old made up as he went along!

You will need: a drinking glass, an egg, lots of salt, vegetable oil, water, Alka-seltzer, possibly a grape, perhaps a chunk of apple, imagination

Experiment: Pour water and oil into a glass add 2 alkaseltzer, a bite of apple, a grape, washing up liquid and an enormous quantity of salt. Finally gently drop in a whole, unbroken egg. The egg floats and everything looks quite pretty!random potion
The science:

Because this was free-style I’m not entirely sure how the effect was achieved but, having done some research with my son, we think the Alka-seltzer and washing up liquid caused the pretty oil effect at the top. Most interesting though, was the floating egg. It turns out that when salt dissolves in water, it makes it denser. In our experiment, my son added enough salt for the water to become denser than the egg which is why the egg floated! You could actually experiment with this by adding different amounts of salt to water and testing to see what objects could float in different solutions.

If you try any of these experiments, I hope you have fun! There are many more to try and I suspect we’ll be experimenting further on 3rd May so watch out for the results on the #THISislearning hashtag!

If you have any experiments or fun learning activities for kids then I’d love you to share them on our #THISislearning linky – more information here!

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