CEIP NARCISO ALONSO CORTÉS

VALLADOLID (SPAIN)

One of the most important

substances for all living things:

AFTER A SERIES OF EXPERIMENTS WITH WATER WE

HAVE LEARNT THAT:

1.There are molecules of water in the air

We put a dry can in the freezer and, after 15 minutes, we took it out and saw that tiny drops of water had appeared on the surface of the can.

FROM THE AIR

Experiment: Condensation

WHERE DID THE WATER COME FROM?

How it works: The gaseous water molecules in the air stick to the cold surface of the can and they condensate.

2. There are absorbent materials and waterproof

materials

We made water lily buds out of paper, then we put them on water and little by little they bloomed.

Experiment: Floating flowers

How it works: When the paper absorbs water, it swells and the molecules of water push the paper outwards, so the petals open.

Experiment: Magic Toothpicks

We laid six toothpicks on water and we put a sugar lump in the middle, then the toothpicks moved towards the sugar lump.

How it works: When we put the sugar lump in the middle of the plate , it absorbs some of the water. A small current of water flows towards the sugar and pulls the toothpicks with it.

3. Liquid water can change into gaseous water

Experiment: Investigating Evaporation

We filled two jars to the same level of water, then we covered one of the jars with a foil cover.

We left both jars in a warm place and after several days , the uncovered jar had a lower level of water.

How it works: The heat makes the water evaporate in both jars, but the foil cover stops the molecules of water escaping into the air, so the level of water remains higher in this jar. Escaneos

de dibujos

4. Salt lowers the freezing point of water

Experiment: Lift an ice cube with a toothpick

We lifted an ice cube with a toothpick by sprinkling a little salt on it.

How it works: When you sprinkle salt onto the ice cube, it makes the ice around the toothpick melt. But no salt falls under the toothpick and it becomes frozen into ice again.

5. Hot water is less dense than cold water

Experiment: Water Volcano

We lowered a little bottle full of hot coloured water into a big jar full of cold water, then the coloured water rose upwards like a volcano.

How it works:The hot water is lighter than the cold water so it rises and floats to the top of the jar.

6. Salty water is denser than fresh water

Experiment: Floating and sinking egg

We put two fresh eggs into two jars, one of them full of fresh water and the other one full of salty water and we saw that the egg inside the salty water floated and the egg in the fresh water sunk.

How it works: Salty water is denser than fresh water, so the buoyancy on the egg in salty water is higher than in fresh water.

7. We can change water surface tension

Experiment: Gigantic bubbles

We made gigantic bubbles by adding some washing-up liquid to a little water.

How it works: The washing up liquid decreases the water surface tension.

We think water is an amazing

substance and we will continue

investigating with the help of our

Comenius partners.