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Beyond the volcano: vinegar and bicarb soda experiments for the classroom!

Written by Jacqui on May 21st, 2017.      0 comments

Title - Experiments with vinegar and bicarb soda (showing three bottles of liquid being squirted into a  beaker)

The countdown begins. The anticipation builds. Steady hands grip the beaker, and empty its contents into the mouth of the volcano. As bicarb soda comes in contact with vinegar, it erupts with glorious foam! Making a vinegar and bicarb soda volcano is a staple in every school kid's science experience. But are you sick of doing the same old thing for the umpteenth time? We've racked our brains to come up with the following list of experiments using vinegar and bicarb soda, to teach not only chemistry or geology, but a plethora of scientific principles!

Time to raid the cupboard...
 
Vinegar and bicarbonate soda chocolate cake!

chocolate cake with one slice cut out on a white plate
Decadent, chocolatey science!

Baking, one of my favourite types of science! It is a wonderful way to teach the importance of following experimental methods, since the deliciousness of the end product depends on it! Common raising agents used in cake making are baking powder, bicarb soda, or eggs. This particular recipe utilises the fizz from the vinegar and bicarbonate soda reaction to give the cake its height, and doesn't require any fancy mixers or equipment. Try varying the amount or ratio of vinegar and bicarb soda as a science project, and see how it affects the cake!
 
Ingredients
 
  • 1 1/2 cups plain flour
  • 1 cup caster sugar
  • 1/2 cup good quality cocoa powder
  • 1 tsp bicarb soda
  • 1/2 tsp salt
  • 1/3 cup oil (olive or rice bran)
  • 1 tbsp vinegar (balsamic is best!)
  • 3 tsp vanilla
  • 1 1/4 cup water
Method
 
  1. Mix dry ingredients in a bowl with a whisk.
  2. Add wet ingredients and whisk until just mixed.
  3. Pour mixture into a greased and lined cake pan.
  4. Bake at 180℃ in a preheated oven for approximately 40 minutes. Check by poking the cake with a skewer, it should come out clean when the cake is done.
  5. Let cool for 10 minutes before handling.
Serve hot with ice cream as a pudding or add icing when it's completely cooled, and you'll have a science lesson for dessert!
 
Fizzy bombs

orange coloured bicarb soda with a spoon in a cup and some red food colouring next to itorange coloured bicarb soda pressed into an ice cube trayorange bicarb blobs and vinegar on a white plate, some covered in white foam
Try using ice cube trays with crazy shapes for extra awesome fizzy bombs!

Here's good one for the little ones. Make colourful bicarb soda bombs and watch them fizz as you drizzle vinegar on them or drop one into a glass of vinegar!
 
What you will need
 
  • A container
  • Spoon
  • 1/2 cup bicarb soda
  • Food colouring
  • Water (optional)
  • Muffin tray or ice cube tray
Method
 
  1. Pour bicarb soda into container, carefully mix in a few drops of food colouring at a time with a spoon until you get the desired colour.
  2. The mixture should be crumbly, and holds its shape when pressed with the spoon. If not, add a few drops of water and mix, repeat until it does.
  3. Fill the muffin tray or ice cube tray with the mixture, about 2/3 of the way up. Pack down with the back of the spoon.
  4. Leave to dry for an hour then turn out onto a plate.
  5. Drip vinegar on top of the fizzy bomb or chuck one into a cup of vinegar!
Endothermic reactions

There are many ways to tell if a chemical reaction has occurred; temperature change is one of them. When vinegar and bicarb soda are undergoing a chemical reaction, the mixture gets noticeably colder! That's because the reaction is endothermic, which means it absorbs energy from its surroundings during the process.

Vinegar bicarb thermometer reading 14.4 degrees celcius in a plastic cup
Easy kitchen chemistry with vinegar and bicarb soda!
 
What you will need
 
  • Foam cup
  • Thermometer
  • 1/4 cup vinegar
  • 1 tbsp bicarb soda
Method
 
  1. Pour vinegar into the foam cup and measure its temperature with the thermometer. Record.
  2. Add the bicarb soda gradually to avoid overflowing foam, stirring with the thermometer.
  3. Record the lowest temperature when the reading on the thermometer stops dropping.
You can ask your students to make observations during the experiment: did the temperature increase, decrease, or stay the same? What else did they notice about the reaction? Comparing results across the class can lead to a discussion about reasons why there might be variations in the results.

As an extension for high school chemistry, you can use this experiment to demonstrate how to calculate the change in enthalpy for a reaction:

delta H equals c m delta T

where:
ΔH = change in enthalpy (kJ),
c = specific heat capacity of water (4.18 kJ kg-1 °C-1),
m = mass of solution (kg),
ΔT = change in temperature of the solution (°C).

Hot ice... an exothermic reaction

One of the products of the vinegar and bicarb soda reaction is sodium acetate. It is used as flavouring for salt and vinegar chips (yum!) as well as the main ingredient for a pocket warmer. 

hands holding blue pocket warmer purple background
Watch as liquid turns to solid while releasing a whole lot of heat!

Pocket warmers contain a supersaturated solution of sodium acetate, where heaps of sodium acetate solids are dissolve in just a tiny amount of water. The solution is liquid until the little metal disk is clicked in and initiates an exothermic crystallisation. The clear liquid turns into a white solid fairly quickly and releasing heat in the process, hence it is often called "hot ice". This cool experiment can easily segue to a discussion about states of matter, or activation energy of a chemical reaction. Here is a video demonstrating how to make sodium acetate with items bought from the supermarket or pharmacy, so you can try making "stalagmites" or "hot ice" with you students too!
 

More vinegar and bicarbonate soda experiments
 
There really is so much you can do with these humble ingredients.
 
white film canisters on black background
Make a Film canister rocket

Kids always asking you to blow something up whenever it's time for science? Now you can say "Yes!" and impress! Discuss the chemical reactions, forces, and energy conversions that are involved plus much more with this simple activity.

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bicarb balloons-81
Making carbon dioxide

Trap the carbon dioxide formed from the reaction between vinegar and bicarb in a balloon. Use it to smother a flame, or bubble through pH indicators and observe the colour change. Compare with a balloon of the same size filled with air, drop them both from the same height and see what happens! A great introduction to the concept of density. 

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Puffed up sandwich bag containing bicarb soda and vinegar
Exploding sandwich bags

This one can get a bit messy! Let your students explore the scientific method the fun way with this experiment and learn about controlling variables.

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nails standing upright
Rusty nail experiment

Another useful activity for teaching variable testing! Why not include a bicarb soda solution to the list of liquids used in this experiment? 

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Volcano eruption experiment (person poring detergent into a cup in front of a mound of sand)
Erupt a volcano

Of course, this classic science experiment is a great complement to any classroom

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As you can see, these versatile kitchen chemicals can be used to teach energy conversions, forces, reaction rates and more. In case you're wondering, the following is the overall reaction which you find traditionally written:

Vinegar + Bicarbonate Soda ---> Carbon Dioxide + Water + Sodium Acetate

i.e

NaHCO3 (aq) + CH3COOH (aq) ----> CO2 (g) + H2O (l) + CH3COONa (aq) 

But really, the reaction occurs in two steps! First, there is double displacement reaction in which acetic acid in the vinegar reacts with sodium bicarbonate to form sodium acetate and carbonic acid:

NaHCO3 + HC2H3O2 → CH3COONa + H2CO3

The carbonic acid is unstable though, so it breaks down into liquid water and carbon dioxide as a gas in a decomposition reaction

H2CO3 → H2O + CO2

Want more experiment ideas? Check out  >100 free science experiments on our website!

Happy teaching,


Jacqui

Jacqui from Fizzics
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