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Home » Science Experiments for Kids » Chemistry » Spooky Lava Lamps – Halloween Science

Spooky Lava Lamps – Halloween Science

Modified: Oct 6, 2023 · Published: Sep 20, 2012 by Emma Vanstone · This post may contain affiliate links · 31 Comments

Lava lamps are one of my favourite things to make. They are very easy to make but really impressive for children to watch.

I also have a pumpkin lava lamp you might like.

homemade lava lamp close up image showing red food colouring and water bubbles rising up through vegetable oil

You will need

  • A clear plastic bottle or jar
  • A bottle of vegetable oil
  • Water
  • Alka Seltzer
  • Food colouring (a spooky colour )

Instructions

Fill the bottle or jar a quarter full with water.

Top up to the (near) top with the vegetable oil.

The oil and water should separate into two layers, water at the bottom and oil sitting on top. Add about 6-8 drops of food colouring once they have separated.

Pop in half an Alka Seltzer tablet and watch the bubbles form.

Add more Alka Seltzer bit by bit to keep the bubbles rising and falling.

DIY lave lamp made with water, black food colouring and oil. Image shows black bubbles rising up through the oil to the surface.

Whatever you do, do NOT shake them up as my 2-year-old did. Let’s just say it was very messy!

What’s going on?

Firstly, water and oil do not mix – this is because water is a polar molecule – its structure means that it has a positive charge on one end and a negative charge on the other. Water molecules stick together because the positive end of one water molecule is attracted to the negative end of another.

Oil molecule structure is different – it is non-polar, meaning that its charge is more evenly spread out, so the oil is not attracted to water – in fact, we call it hydrophobic (water-fearing) as it tries to get as far away from water as possible and will not mix.

The reason that oil rests on top of the water rather than underneath is because it has a different density to water.

As the alka seltzer is added (this is made of citric acid and sodium bicarbonate), it reacts with the water to form carbon dioxide gas and sodium citrate. It is the carbon dioxide bubbles that carry the coloured water to the top.

spooky lava lamps made with coloured water and vegetable oil for a Halloween science activity

Last Updated on October 6, 2023 by Emma Vanstone

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Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

Comments

  1. maggy, red ted art

    September 21, 2012 at 5:36 pm

    Ooh they look great! That second one looks like frog spawn. Yeeewwww.

    Reply
    • ScienceSparks

      September 23, 2012 at 1:00 pm

      ha ha 🙂

      Reply
    • michelle trujillo

      October 25, 2013 at 2:16 am

      I thought that was really cool I really liked the first lava lamp pic.

      Reply
  2. Crafty Kiddies

    September 22, 2012 at 12:31 am

    I always assumed that these were much harder to make – sure Scamp would LOVE to make a pink version so we’ll try to have a go!

    Reply
    • ScienceSparks

      September 23, 2012 at 12:59 pm

      they are fab, and you can reuse them!

      Reply
  3. Bethany @ No Twiddle Twaddle

    September 23, 2012 at 8:56 pm

    Those look very neat. We will have to try making them some time.

    Reply
  4. Mary

    September 25, 2012 at 12:49 am

    I’ve never heard of adding alka seltzer (where have I been?). These are great! Thanks for the ideas!

    Reply
  5. Jill @ A Mom With A Lesson Plan

    September 27, 2012 at 7:09 pm

    Alka seltzer is a fantastic idea! The kids are going to love this one!

    Reply
    • ScienceSparks

      October 03, 2012 at 8:50 am

      It is very cool.

      Reply
  6. Joanna

    October 02, 2012 at 3:31 pm

    Is there a way to print out how to make the lava lamps? Its a great idea but I can’t have 20 kids around one computer to find out how to do this.
    Thanks.

    Reply
  7. Emma

    October 08, 2012 at 9:38 am

    I have just discovered this site and it’s great. My daughter aged 4 is just getting into science and I was thinking about buying her a science kit but now I think I can use these ideas instead!

    Reply
    • ScienceSparks

      October 08, 2012 at 6:56 pm

      Thats so lovely to hear. Thank you. xx

      Reply
  8. Kathy

    October 14, 2012 at 2:10 am

    I’ll try these on Halloween and let you know how it goes… I plan on dressing as a mad scientist… the kids will love it!!!

    Reply
    • ScienceSparks

      October 15, 2012 at 6:30 am

      oooh that sounds fun!

      Reply
  9. Deborah

    October 19, 2012 at 9:40 pm

    Thank you for the great instructions! I haven’t tried the alka seltzer before. I would like to see how long it lasts.

    Reply
  10. T Lake

    October 23, 2012 at 5:26 pm

    Great idea!
    With plastic, would you have to leave the cap off or just make sure it’s screwed on really tight? Don’t want it exploding in the faces of my class!
    Also, would it work with dissolvable asprin as I am out of Alka Seltzer and not sure I can make it to the shop in time….
    Thanks!

    Reply
    • Gloria

      October 11, 2013 at 6:34 pm

      I’m going to try it for my grands bday party 10/31 thanks, oh and for school too LOL

      Reply
      • ZARI

        April 25, 2014 at 1:10 pm

        This is a great activity for the end of the year after CRCT testing. I will be doing this with my class. Thank You so Much.

        Reply

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