Experiment 1: A Chemical Pop Gun

Required: Effervescent tablet, empty plastic cylinder, water

Fill the cylinder to 1/4 with water, add one tablet and close the cylinder immediately with the plastic stopper. Hold it in a safe direction, away from other students!

Explanation:

A chemical reaction can only occur if particles are mobile. As long as the tablet is dry the various particles are fixed. In water the start moving and hence react, in our case under liberation of gas.


Experiment 2: Carbondioxide Geyser

This is a demonstration experiment!

Required: empty plastic detergent bottle ( 500 [ml] ) e.g. Pril with special stopper, powder funnel, teaspoon, sodiumhydrogencarbonate, washing-up liquid, citric acid

Fill ca. 200 [ml] of water into the bottle and add two teaspoons of sodiumhydrogen-carbonate (“baking powder” “baking soda”). Add ca. 30 [ml] of washing-up liquid and shake.
Finally three teaspoons of citric acid are added by using the funnel. Close the stopper, shake and open it after 15 seconds.

Be ready to clean!

You can repeat the geyser quite often by closing / opening the bottle.

Explanation:

The acid reacts with the base under emission of carbondioxide gas.
Carbonates and Hydrogencarbonates can easily be removed from their salts through stronger acids whereby carbonic acid is liberated.
At s.t.p. carbonic acid is unstable and disintegrates after:
H₂CO₃  ———>  CO₂ + H₂O