Physics and Chemistry experiments for primary and high school students

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Chemical Reactions: exp 1-4
1) How to inflate a balloon with CO2
Materials: A volumetric flat flask, a teaspoon, a balloon,a spatula, sodium bicarbonate (NaHCO3),vinegar and a funnel.
What to do: Put 1 teaspoon of sodium bicarbonate inside the ballon (use the funnel can make it easier) and 25ml of vinegar inside the flask. Carefully put the ballon on flaskneck in order to avoid the bicarbonate coming out. Now put the balloon in vertical position providing that all the bicarbonate follow down and dissolut into the vinegar. The vinegar start to fizz in the flask e then the balloon start to swell.

What happens: The acetic acid (CH3COOH, also known as ethanoic acid) of the vinegar reacts with the bicarbonate (a base) producing carbon dioxide (CO2)that generates the fizz. Carbon dioxide rises in the flskneck and inflates the balloon.

2) Dancing mothballs

Materials: Some of motheball, a becker, a teaspoon, sodium bicarbonate, water (also food coloring but it is not necessary) and vinegar.

What to do: Put in a becker of 600ml 2 round teaspon of sodium bicarbonate and add 250ml of water (the food coloring and the mothballs)Before adding the vinegar the mothballs will lay on the bottom of the becker. Then add 40ml of vinegar. The balls start to travle toward the surface of the liquid and then move toward the botton, up and down.
What happens: The mothball are made of naphthalin (or antimite, C10H8) have a density slightly higher than water and for this reason it deposit on the bottom of the becker with the water. When vinegar is added, the reaction between the acetic acid and the sodium bicarbonate (as in the previous experiment) produces carbon dioxide and then the solution start to fizz. Carbon dioxied bubble deposit on the mothball surface and they really pull the ball up to the surface of the solution. Such bubbles when are in contact to the air, they crash and mothball follow down again reachng the bottom of the becker. Here new generated bubbles of carbon dioxide drag the ball again in the surface and the up-and-down trip re-starts.

Additional informations: Naftalhene is a cristallyne material, volatile, with a sharp smell and not soluble in water. Older mothballs consisted primarily of naphthalene, but due to naphthalene's flammability, modern mothballs use 1,4-dichlorobenzene instead. It was used for killing moth ans moth larvae with its vapor, being placed with out-of-season clothings in a sealed container. But nafthalene is also used for killing silverfishes, as repellent for snakes, as solvent, as lubrificant, etc.

3) How to inflate a balloon with hydrogen

4) The invisible ink

Materials: a lemon, a white paper sheet, a small brush, a bowl, a candle

What to do: squeeze the lemon into the bowl and dip the brush inside the juice. Write down some word (or an entire small message) in the white paper sheet and let wait until the "ink" dried and disappeared. Pass the sheet over a lighted candle without burning it, then... the written words reappear
What happens: the citric acid (C6H8O7) inside the lemon juice is colorless in acqueous solution, but, when it is heated, it oxidizes and becomes brown colored.

Pressure and vacuum: exp 5-7

5) The Stevino's law

6) The vacuum pump

7) The thirsty glass and the candle

Tensioactives, surface tension, capillarity: exp 8-10

8) Tensioactives and pepper

9) The blossoming flower

10) The infinite drops

Density: exp 11-12

11) The floating egg

12) Oil, water and alcohol

Optics: exp 13-16

13) Words afloat

14) The red sunset

15) The Benham disk

16) The diffraction and the measurement of microscopic objects

Other phenomena: exp 17-21

17) The fireproof balloon

18) The Crookes radiometer

19) The cornflour

20) The needle and the ballon

21) Solar energy