by Deb on April 26, 2010

Post image for Volcanoes

At the request of the lovely Sophie and in honour of Eyjafjallajokull, we made a volcano.  Luckily ours was a lot safer and has had absolutely no effect on international air travel.  And I promise I’m really not going to load every post up with videos from now on, but admit it – don’t you want to see the eruptions?

Make your own volcano, simple:

  1. Build up a cone out of dirt.
  2. Put a smallish container in the top, a baby food jar or the bottom of a drink bottle is perfect.
  3. Put loose sodium bicarbonate (bicarb soda) into the jar.
  4. Pour in some vinegar and watch the lava flow!


  1. Add some food colouring to look pretty.
  2. Add some detergent.

You can do it the other way around and put your liquids in the jar and pour your bicarb in last.  In my experience little kids find it easier to pour the vinegar than a powder.

What’s happening?

This is an example of an acid/base reaction.  Vinegar is an acid, and sodium bicarbonate acts as a base.   At a very basic level (pun intended), you have:

baking soda (sodium bicarbonate) + vinegar (acetic acid) –> carbon dioxide + water + sodium acetate

NaHCO3(s) + CH3COOH(l) –> CO2(g) + H2O(l) + NaCH3COO(aq)

where s = solid, l = liquid, g = gas, aq = aqueous or in solution

The carbon dioxide, of course, is a gas and produces the bubbles, but the vinegar/water solution isn’t very strong and they grow big and collapse quickly.  Detergents, on the other hand, produce lots of nice stable foam.  This is because they are quite sticky and they interfere with the surface tension, it is hard for bubbles to grow big but they last for a long time.  Food colouring just looks pretty.

It’s beautifully safe for kids to play with, with the usual proviso of not getting it in your eyes.  The 2 year old was happily pouring vinegar in and doing everything and they both enjoyed putting a bit of bicarb on their hands and feeling the bubbles.  With older kids you could make an elaborate permanent volcano out of a flour/salt dough and even add vegetation to be washed away by the boiling lava.  I wonder if they could concentrate enough to look at the flow patterns or if seeing it all erupting over the top is too interesting!

Have fun 🙂

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{ 13 comments… read them below or add one }

Miss Carly April 26, 2010 at 9:27 am

This is such a fun experiment with almost all age groups!


Catherine April 26, 2010 at 12:11 pm

My son loves doing this!
.-= Catherine´s last blog ..postcard swap =-.


Sophie April 26, 2010 at 4:41 pm

Thanks so much for doing this, we havent done it in a long time. How much fun it is and the kids love being in charge, the effects are fun too 😉


Kristine April 26, 2010 at 9:42 pm

You can make a really cool ice-cream volcano.
Carve a 2L container of ice-cream into a mountain shape. Hollow out a cup shaped mouth in the top. Re-freeze. Then pour in red creaming soda (or lemonade and red colouring) and watch it blow!

PS I finally finished the knit dresses I was lamenting about! Thanks for your advice.


Deb May 2, 2010 at 2:12 pm

Yum, red creaming soda and icecream sounds like a great combination. I think that sounds brilliant for a birthday around here.


Narelle April 27, 2010 at 2:30 pm

I so have to do this with my own kids!! I used to do it for the kids I taught when we did our ‘natural disasters’ unit. It was great to do with special needs kids because they could get really involved. We made a papermache ‘volcano’ which was a great sensory activity by itself and then put the bicarb and vinegar in the bottom. It’s so easy to forget about doing all this fun scienc-y/sensory stuff with your own kids, I used to do it so much with the kids I taught!
.-= Narelle´s last blog ..More sewing creations for little girls! =-.


PlanningQueen April 27, 2010 at 9:29 pm

Loved the video Deb and the very thorough explanation in the post. I also like that I will now be able to hear your voice when I read your Tweets!
.-= PlanningQueen´s last blog ..10 Children’s Activities For May 2010 In Melbourne =-.


Deb May 2, 2010 at 2:13 pm

I’m still getting used to it – that’s not what I sound like! Except for the dagginess, that’s me.


Julie April 29, 2010 at 10:54 am

I love this idea. Will have to store it away for when mine are a little bigger. Incidentally, that is how I clean my bathroom drain! I put a tablespoon of bicard soda in, wait about 20 minutes and follow-up with 1 cup of vinegar. It does make a good fizz.
.-= Julie´s last blog ..Play for new babies =-.


katepickle April 30, 2010 at 4:14 pm

This one of the most fun science activities I’ve ever done with little kids… so much fun and so much to learn! My kids really loved watching your volcano erupt!


Christie - Childhood 101 May 3, 2010 at 3:00 pm

You make science look so easy, I always found it quite a tricky subject to teach, especially keeping it hands on with a class of young ones. What fun!
.-= Christie – Childhood 101´s last blog ..Stopping Bullying Before It Begins: Part 2 =-.


Deb May 3, 2010 at 9:51 pm

Thank you. My philosophy is that if it’s hands on, it’s science lol! My sister is an artist, she looks at the same activities I do and sees the art, I see the science. It seems to be a bit more unusual, which is why I love sharing that perspective. And it’s fun!


Melissa May 5, 2010 at 9:38 am

I’ll definitely have to do this with my boys. It’s been ages since I’ve made a volcano like this!
.-= Melissa´s last blog ..A challenge =-.


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