I wanted to make some tablets with baking soda in them, since the sodium bicarbonate in them would fizz in vinegar. The chemical reaction is:

Sodium bicarbonate plus vinegar produces sodium acetate, water, and carbon dioxide gas

NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂

The main challenge was how to hold a powder mixture together. We tried agar agar powder, and corn flour, but the tablets were fairly crumbly. Then we tried gelatine powder, and that worked quite well.

We used baking soda and gelatine powder in equal quantities, with a little food colouring. The gelatine was to help hold the tablet together and to slightly slow the reaction. The food colouring was for interest and to help stick it together.

A garlic press worked well for compacting the mixture. We inserted a piece of plastic inside, across the holes, to press the mixture against.

When we wanted to get the tablets out we used a pin to push the disk (and tablet) out.

And this is what happens when you put one in vinegar:

[vimeo https://vimeo.com/124491977]

Next project is to see if we can make tablets with citric acid in them, so we can add one tablet of each to water, instead of needing vinegar.