Tuesday, 28 April 2009


1 One small container and one larger glass
2 Oil
3 Water
4 Glue and one coin
5 Spoon
6 Alcohol

1. If the container is of plastic we put on the base one coin to give it stability and to avoid that it floats.
2. You take the small container, and you fill the container until the middle with oil and you see that the oil sets on the bottom of the glass.
3 Inside the glass you fill with precaution, the amount of alcohol that you need to cover the small container. Then with a spoon, you add, little by little, water.The surface of the oil from the small container will be more and more convex, when the water that you have added is the necessary, the oil will give off the container and will forma sphere that will be floating inside the mixture of water and alcohol.

The densities of the three liquids : water (1g/ml), oil (0,92g/ml) and alcohol (0,79g/ml).
The oil floats on the water because it is less dense than the water, but the oil doesn’t float on the alcohol because it is denser. So you can prepare one mixture of water an alcohol, where this oil won’t float and won’t sink until the bottom.

by Macarena, Irene and Sofía

Saturday, 25 April 2009

A whirlpool in a bottle


Two bottles made of plastic 1,5 l.
Insulating tape


First, we make a 1 cm hole at the tops of the bottles. Then, we fill one of the bottles with 75% of water and join the bottles by means of the tops. To join the two bottles we use the insulating tape. This joint is very important, so do not be stingy with the insulating tape.

When the bottles with water is on top of the other, the water does not fall easily to the empty bottle, but if we make a circular movement with the upper bottles, it generates a whirlpool, and the water falls easily.


When we place the bottles full of water on the top, the water does not fall because of the low compressibility of the air, which takes up the lower bottle and does not let any space for the water to fall.
By the time, the whirlpool is generated by the air of the two bottles that passes from one to the other and the water of the upper bottle falls easily.

By Mercedes and Fátima

The extintor


- Sodium bicarbonate.

- Vinegar.

- A glass.


- A candle

Frame up:

Put inside a glass a little of vinegar ( three or four centimetres)
Add a little sodium bicarbonate. Then many bubbles appear.
Light a candle with a match. If you tilt the glass without spilling vinegar, we see that the candle puts out.


The chemical reaction between sodium bicarbonate and acid vinegar producers a gas called Carbon Dioxide. This gas is heavier than the air and it stays in the glass by moving the air in the glass.
When you put the candle next to glass it´s turned off by the lack of oxygen. When you tilt the glass, it´s put out because the carbon dioxide, displace the oxygen that retain the combustion.

by José Ángel and Miguel

Saturday, 18 April 2009

Ruler and newspaper

To make our experiment we need a ruler made of plastic, a sheet of newspaper and a heavy object.

First we place the ruler on a table so that the middle part of the ruler is on the edge of the desk. If we drop a heavy object on the part that stands out we see that the ruler falls down from the table.

We repeat now the experiment by placing a newspaper sheet extended on the part of the ruler that is on the table. If we draw now the same object on the part that stands out we see that the ruler doesn't fall to the floor.

What makes the ruler stop? Is it an invisible hand or perhaps the weight of the newspaper sheet?

The correct answer is the pressure and the strength in the atmosphere on the newspaper sheet.

It´s very easy and you can do it at home. Will you do it there?

by Marta and Claudia

Tuesday, 7 April 2009

The water that is not wet

To make the experiment we need:

1) A glass
2) A piece of paper
3) A big countainer with water

We have to fill a countainer with water, then we put a piece of paper at the botton of the glass so that, it won´t fall when we turn it down. Later,we turn round the glass and we put it with the paper into the borron of countainer. It´s so important not to till the glass.

Finally, we take the glass out of the countainer and we check that the piece of paper isn´t wet.

The explanation is quite simple the air contened into the glass blocks the water to enter and arrive to the piece os paper which is at the botton of the glass.

by Marta and Isabel

Thursday, 2 April 2009

Candy chromatography


Group 5 - Elena B, Cynthia C, Karina L, Laura P - Colegiul Naţional "Mihai Eminescu" Satu Mare, România

Ever wondered why candies are different colors? Many candies contain colored dyes. Bags of M&Ms or Skittles contain candies of various colors. The labels tell us the names of the dyes used in the candies. But which dyes are used in which candies? We can answer this by dissolving the dyes out of the candies and separating them using a method called chromatography.

For this experiment you will need:LP_candies.gif

• M&M or Skittles candies (1 of each color)
• coffee filter paper
• a tall glass
• water
• table salt
• a pencil(a pen or marker is not good for this experiment)
• scissors
• a ruler
• 6 toothpicks
• aluminum foil
• an empty 2 liter bottle with cap

Cut the coffee filter paper into a 3 inch by 3 inch (8 cm by 8 cm) square. Draw a line with the pencil about ½ inch (1 cm) from one edge of the paper. Make six dots with the pencil equally spaced along the line, leaving about ¼ inch (0.5 cm) between the first and last dots and the edge of the paper. Below the line, use the pencil to label each dot for the different colors of candy that you have. For example, Y for yellow, G for green, BU for blue, BR for brown, etc.

Next we’ll make solutions of the colors in each candy. Take an 8 inch by 4 inch (20 cm by 10 cm) piece of aluminum foil and lay it flat on a table. Place six drops of water spaced evenly along the foil. Place one color of candy on each drop. Wait about a minute for the color to come off the candy and dissolve in the water. Remove and dispose of the candies.

Now we’ll “spot” the colors onto the filter paper. Dampen the tip of one of the toothpicks in one of the colored solutions and lightly touch it to the corresponding labeled dot on your coffee filter paper. Use a light touch, so that the dot of color stays small - less than 1/16 inch (2 mm) is best. Then using a different toothpick for each color, similarly place a different color solution on each of the other five dots.

After all the color spots on the filter paper have dried, go back and repeat the process with the toothpicks to get more color on each spot. Do this three times, waiting for the spots to dry each time.

When the paper is dry, fold it in half so that it stands up on its own, with the fold standing vertically and the dots on the bottom.

Next we will make what is called a developing solution. Make sure your 2-liter bottle or milk jug is rinsed out, and add to it ⅛ teaspoon of salt and three cups of water (or use 1 cm3 of salt and 1 liter of water). Then screw the cap on tightly and shake the contents until all of the salt is dissolved in the water. You have just made a 1% salt solution.

Now pour the salt solution into the tall glass to a depth of about ¼ inch (0.5 cm). The level of the solution should be low enough so that when you put the filter paper in, the dots will initially be above the water level. Hold the filter paper with the dots at the bottom and set it in the glass with the salt solution.

What does the salt solution do? It climbs up the paper! It seems to defy gravity, while in fact it is really moving through the paper by a process called capillary action.

As the solution climbs up the filter paper, what do you begin to see?

The color spots climb up the paper along with the salt solution, and some colors start to separate into different bands. The colors of some candies are made from more than one dye, and the colors that are mixtures separate as the bands move up the paper. The dyes separate because some dyes stick more to the paper while other dyes are more soluble in the salt solution. These differences will lead to the dyes ending up at different heights on the paper.

This process is called chromatography. (The word “chromatography” is derived from two Greek words: "chroma" meaning color and "graphein" to write.) The salt solution is called the mobile phase, and the paper the stationary phase. We use the word “affinity” to refer to the tendency of the dyes to prefer one phase over the other. The dyes that travel the furthest have more affinity for the salt solution (the mobile phase); the dyes that travel the least have more affinity for the paper (the stationary phase).

When the salt solution is about ½ inch (1 cm) from the top edge of the paper, remove the paper from the solution. Lay the paper on a clean, flat surface to dry.

Compare the spots from the different candies, noting similarities and differences. Which candies contained mixtures of dyes? Which ones seem to have just one dye? Can you match any of the colors on the paper with the names of the dyes on the label? Do similar colors from different candies travel up the paper the same distance?

You can do another experiment with a different type of candy. If you used Skittles the first time, repeat the experiment with M&Ms. If you used M&Ms first, try doing the experiment with Skittles. Do you get the same results for the different kinds of candy, or are they different? For example, do green M&Ms give the same results as green Skittles?

You can also use chromatography to separate the colors in products like colored markers, food coloring, and Kool-Aid. Try the experiment again using these products. What similarities and differences do you see?

Wednesday, 1 April 2009


-A plastic bottle
-Transparent tube of a pen
-Insulating tape and scissors
-Elastic rubber

1. Fill the bottle with water.
2. Cover one hole of the pen with insulating tape. If the pen has got a lateral hole, it has to be covered too.
3. Join the clips to the pen with the elastic rubber, in order to float with the open hole inside the water.
4. Close the bottle.

When you press the bottle, you can see how the pen goes down to the bottom of the bottle. When disminising the pressure, the pen goes up again.

Pascal's and Archimedes' Principle allow us to explain the experiment.
Before pressing the bottle, the pen floats due to its weight is smaller than the thrust power made by the water.
When you press the bottle, the pressure is transmitted to the bottom of the pen and the water enters in the bottom, so its produces an increasement of the pen's weight (the aire is sustituted by the water)When the weight is higher to the thrust, the pen sinks.
When you stop pressing, the water comes off and the pen goes up.

by Julia and Begoña