A 500ml bottle

A straw


Bicarbonate of soda

The use of a drill


You want to build a nozzle into the lid of the bottle, to do this first drill a hole in the top (or get someone with a drill to make the hole for you.

Drill hole in capStraw through bottle top
Drill a hole in the bottle capIt should be large enough to fit your straw

You then need to hold the straw into the cap against some pressure, so put some plasticine, or blue tack around the straw, inside and outside the cap

Plasticine inside bottle topPlasticine on outside of lid
Seal the inside with plasticineSupport the straw and weight the stern of you boat with more on the outside

The plasticine on the inside is most important for making a seal, as the pressure will tend to push it against the straw, on the outside it is mostly acting as support and weight to make sure the straw is below the liquid level inside the bottle.

Fill the bottle a third full of water and test that it floats fairly level but with the neck of the bottle lower than the base.

If you are using strong vinegar dilute it with it's own volume of water.

Now fill the bottle a third full of vinegar.

Very quickly add 1/2 a teaspoon of bicarbonate of soda, put the lid on, and put the bottle into a bath or a sink.


You should find that a jet of vinegary water is shot out of the straw and the bottle is pushed through the water.


Bicarbonate of soda (Sodium hydrogen carbonate) has carbon-dioxide gas locked up inside its structure, if it reacts with an acid such as Vinegar (acetic acid) it releases carbon-dioxide gas

Sodium Hydrogen Carbonate + Acetic Acid -> Sodium Acetate + Water + Carbon-dioxide

This carbon-dioxide is a gas so has a much larger volume than the vinegar and Bicarbonate of soda so it bubbles up and it pushes outwards, building up the pressure

Reaction in the bottleThe pressure builds up
The bicarbonate of soda and vinegar react producing carbon-dioxide gasThe pressure builds up forcing water and vinegar out of the straw

This pressure pushes vinegar and water out of the straw 

The equal and opposite reaction pushes the boat along, using the same principle as a jet or rocket.


Is the volume of gas affected if the vinegar and baking soda are mixed up?

The volume isn't affected, but the speed of the reaction is. If you mix the ingredients well, the gas is created faster, resulting in more pressure for the propulsion.

Why is baking soda the only substitute
for bicarbonate can't you use something else, I'm a homeschool girl
and I can't afford to get behind so I really need an affective substitute for bicarbonate

It isn't only baking soda that will work, anything (safe) containing a carbonate that will react with an acid to produce a soluble product (otherwise the reaction will stop) will be fine.

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