A lazy, active volcano. 

I’m a lazy mum, honestly I am. I see so many interesting things to do but if it requires a shopping trip and more than 15 mins prep then it has lost me – it takes a lot of energy to clean bums whilst plastering an ever lasting smile on my face!!

The kids were watching an episode of ‘My Family’ on CBeebies on the other day and witnessed a family build a volcano – the whole shabang. Pva glue mixed with water, newspaper, dipping it all in, sticking it on, waiting for it to dry, paining it and then creating the magic.

My eldest turned it me with big bright brown eyes, an eager smile and said, “Can we do that mummy?”

My ever lasting smile started falling off my face. Ahhhhhh!! Noooooo! Please no! The mess! And I’ll be doing most of the work! But I kept calm and composed. “Yep, maybe we can.”

After doing a bit of research and thinking I was very happy to come across the idea of a ‘backyard volcano’ which literally was a volcano shaped out of a mound of dirt. No glue. No dripping mess. THIS we could do. So we did!

Now the kids had already seen a demonstration on television so they knew what was going to happen. Also, we’ve worked with vinegar and bicarbonate of soda (the ingredients needed to do this experiment) before – when we were looking at blowing up a balloon, which meant I had to think carefully about how to get some learning out of today’s activity.

So I decided that the following question was posed: Which would create the better/more explosive volcano – adding baking soda to vinegar? Or vinegar to baking soda?

I began the activity talking about volcanoes to see what they already knew. I then showed them a video about volcanoes which you can find here. We re-watched the CBeebies show and pointed out the ingredients they used to make the explosion. Had we used them before? My youngest was quick to say ‘egg!’ She picked up on the vinegar and remembered we had used it to make the bouncy egg – I was super impressed! I reminded them about the balloon experiment and with a little prompting they (well the eldest) remembered a few key words such as carbon dioxide. My youngest then went looking for the vinegar in the kitchen!! They remembered it looked like water and also did not fall for the ‘Mmmm, smell it’ trick!

I gathered the rest of the things needed. For this you will  need:
Bicarb of soda
Food colouring
2 containers/cups
A jug & spoon

Whilst the kids were busy putting their shoes on I poured the vinegar into the jug and mixed in the food colouring (a large amount!)

Off we headed into the back garden. We have lots of gravel/stones in our garden in certain areas – it was with this we created a ‘mound’. You can do it with sand, soil/mud if you prefer or have that to hand instead. If none of these are available then do not worry! You could do this whole experiment with 2 cored apples!! By removing the core of the apple, you have your ‘container’. Just make sure they are the same type of apples because different types of apples can effect the result – but that’s a whole other experiment. When doing science its best to change one variable at a time – so keep it fair and simple.

In the top of the mound the cup was placed and pushed down. We created two volcanoes as we would be comparing the explosions created by changing when an active ingredient would be added.

In one volcano we added bicarb of soda to the cup. In the other we added the vinegar.

Now the preparation was fully complete it was time to make predictions. Which would create the more explosive volcano – adding vinegar to baking soda? Or adding baking soda to vinegar?

Each volcano was tested individually and here are the results…..

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The kids LOVED this. So did I – and no mess to clean up (well apart from washing the pots and jug – but when is there not washing up??). The stones were flattened out and the rain will wash away the rest.

The science bit:

The vinegar (acid) and bicarb of soda (base) mix to make an acid-base reaction, producing carbonic acid. This product is very unstable and splits to form water and carbon dioxide which expands and rises up. Having the vinegar poured directly onto the soda (so putting the soda in the cup first) means that the vinegar makes contact with as much soda as possible and so produces a ‘better’ result than adding the bicarb to the vinegar.

Bicarbonate of soda
Carbon dioxide

Key questions
What do you know about volcanoes?
What colour is lava?
What happens when you mix vinegar and bicarbonate of soda?
What is the gas that is made?/Why are there bubbles?
Which will make the bigger/better explosion?

Simple, cheap, quick and explosive fun…..ENJOY!