Lemon Volcanoes

We never tire of baking soda and vinegar experiments. We love the foaming, fizzing reaction that occurs when the two are combined. But did you know that you can combine baking soda with citric acid, to create a similar bubbly reaction? These Lemon Volcanoes are so much fun to create! Our little nugget loved experimenting and exploring with these vibrant yellow citrus fruits. And I must say…the lemony aroma is much more pleasant than the smell of vinegar. 🙂

Science is so cool! I love watching chemical reactions. And I love watching my little nugget’s eyes light up with wonder and fascination, every time we conduct an experiment. I really wish we did more visually-engaging science experiments in school, when I was growing up – I certainly would have been a lot more interested. Here’s hoping I can help my daughter develop an early love for science!

The specific science behind this lemon volcano experiment, is the classic reaction between an acid and a base. When the citric acid (lemon juice) combines with the base (baking soda/sodium bicarbonate), a chemical reaction takes place, producing carbon dioxide gas (i.e. bubbles). A small amount of sodium citrate is also produced – a sour salt that is mainly used as a food additive, or preservative. It’s what gives club soda its sour and salty flavor.

I stumbled across this Lemon Volcano Science Activity, over on Babble Dabble Do.

Supplies:

Lemons (two lemons per volcano)
Food Coloring
Dish Soap
Baking Soda
Tray/Rimmed Cookie Sheet
Popsicle/Craft Sticks
Small Glass/Cup
Sharp Knife
Small Spoon

Instructions:

Divide the lemons into two groups – a volcano group and a juice group. The lemon prep requires the use of a sharp knife, so an adult should help with this initial step. Slice the bottoms off of all of the lemons in the volcano group (so that they sit flat). Now slice (core) the top of each of the volcano lemons (similar to how you would cut the top off of a pumpkin when you carve it for Halloween). Set the lemons upright on a tray or rimmed cookie sheet.
Cut all of the remaining lemons (in the juice group) in half. Squeeze all of the lemon juice out into a small glass or cup.
Make sure to have all of your ingredients close at hand and readily accessible.
Start by repeatedly jabbing a popsicle/craft stick into each lemon volcano, to release as much lemon juice as possible. Make sure the lemon juice stays inside the lemons!
Next, add a few drops of food coloring to each lemon volcano.
Place a squirt of dish soap on top of the food coloring. The dish soap just adds to the bubbly fun!
Add a spoonful of baking soda on top of the dish soap. At this point you will start to hear fizzing, and you will notice small bubbles starting to form, as the baking soda combines with the citric acid.
Pour some of the extra lemon juice on top.
To get the foamy bubbles really flowing (and to bring out the color in each volcano) jab the popsicle/craft stick into the lemons.
Sit back and watch the magic happen!
Feel free to continue adding the different ingredients, to keep the volcanoes going.

Our little nugget can never resist putting her hands into the bubbly mixture. This time she had the added sensory bonus of squeezing all of the colored foam out of the lemons, and then putting her entire hand inside each lemon, because…well, why not? 🙂 I love watching her experiment and explore!

Citric acid can also be found in other citrus fruits. We just might have to try this colorful, foaming experiment with some grapefruits, oranges, and limes. I would expect the reaction to be a bit less bubbly with the oranges and grapefruits, since lemons and limes contain more citric acid than any other citrus fruit…but you never know until you test the hypothesis. There is one thing I know for sure though…our house will never smell better! 🙂