ONLY FOR GROUP 2

The glucose is a substance that is a reducer and the methylen blue in its blue form is an oxydant, so when we let the reaction lay the colour starts disappearing as the methylen blue is reduced in its colourless form. However when we shake the bottle, we raise the amount of oxygen into the bottle. Then the oxygen oxidises the methylen blue back to its blue form. We can repeat the experiment many times until glucose and oxygen are completely consumed. the methylene blue gets reduced and the glucose oxidises, creating a redox reaction, and making the bottle aquire the blue colour again. Having the oxygen into the reaction makes the oxidation happen, but then the oxydant gets reduced, and then, after the substance gets oxygenated the reaction returns to its orignial state.

To be completed

Carefull with the vocabulary: a reducing agent (or reducer) reduces an oxydant ( or oxidizing agent) or is oxidised by an oxydant  BUT an oxydant oxidises a reducer or is reduced by a reducer. You forgot the role of oxygen in your explanation. Try to ask your french partner if you can't find out by your own.

N.Hoang (French science teacher)

OK. 2nd revision (I've made some corrections by myself)

Spain 1

(Pais Vasco)

Materials :

- Acetone

- Expansed polystyrene

- Cup

Explanation :

The polystyrene is full of air bubbles. The Acetone acts like a solvant and when it meets the polystyrene, this one is quite dissolved and the air of the bubbles escapes, so the polystyrene becomes smaller.

OK. N.Hoang

by Spain 2 group 2

We can see that when the girl move the dock it moves like a wave. Then the dock start to move in a periodic motion. It's necessary two points of support  in order to this phenomenon takes place.This movement is produced by a dock that performs a transverse wave, this means that  to produce  the wave motion we apply a vertical force while the wave is transmited horizontally.

Ok ... perhaps you can add some observations about this points that seems to be steady. (P. Sirabella)

Spain 2

(Valencia)

by Italian group 2

The foaming is caused by the presence of chemicals like potassium benzoate and aspartame in Diet Coke, and gelatin and gum arabic in the Mentos. The nucleation reaction between the chemicals, which influence the nature of water's surface tension, causes an increase of carbon dioxide gas bubbles that create the eruption.