ONLY FOR GROUP 6

In this experiment you put milk in two different containers. Then in the first container, you put some drops of colorant.In the second container you put again some drops of colorant. Later, with a magic wand that has soap we move the first mixture and nothing happened because in this container we use fermented milk and this type of milk has not grease , in the second ,we touch the mixture with a magic wand that has soap too. Suddenly, a lot of figures appeared because the molecules of the soap stand on top of the milk,in this container we use whole milk which has grease, when there is  grease in the milk the surface tensions are  different and the grease separates from the soap. When there is not grease in the milk, the soap and the milk mix because the surface tension is very similar.

The 2 milks are different in the 2 containers. Can you find out ? In fact there is soap at the end of the "magic wand" in both cases. Can you explain what's happened in a scientific point of view between the molecules of milk on the surface and the soap ?

A clue : it deals with the surface tension...

Ask Anton to correct your sentences. The last one is too long and I am not sure to understand well what you mean !

N.Hoang (French science teacher)

Spain 1

(Pais Vasco)

The pupils put in a beaker 2 colourless liquids. In 6 seconds the liquid becomes black opaque. In the first beaker there is potassium iodate (KIO3) and the second includes sodium bisulphite (NaHSO3). These two substances are put together (starch has also be added but we do not know it on the video). In 6 seconds, the mixture becomes black. 

In this experiment,  reaction the starch step in
When the liquid has been shaken, there are 3 reactions : 
The two first ones reactions are slow and create the iodine I2.

The third reaction is very fast, the bisulfite ion HSO3- consumes the iodine I2 previously formed and the reaction creates the iodide ion I-.When the bisulfite ion is totally  consumed, the iodine will survive to form the dark blue compound with starch.

The all vitesse changements train the color changement, the transparent color becomes black.

Correct your English mistakes !

In fact there is starch in this experiment. And starch and iodine I2 form a blue-black substance. There are in fact 3 reactions. The 2 first ones are slow and form the iodine I2. The 3rd reaction occurs between the iodine I2 previously formed and the bisulfite ion HSO3- to produce the iodide ion I-. This 3rd reaction is fast. When the bisulfite is fully consumed, the iodine will survive to form the dark blue compound with starch.

N.Hoang

N.Hoang

2nd revision (I corrected myself !!)

 

Spain 2 group3

Practice 6  starch- iodine water experiment
Starch is formed by molecules of amylosa and amylopectin. Forms of glucosa. Amylosa is responsable of the intensive blue color with iodine. When the mixture is heated the amylosa estructure change and a change of color is observed

OK

ML Tibaldeschi