Thames & Kosmos Ooze Labs: Chemistry Station handleiding

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Handleiding

Powder detective

In this experiment, you can test for two

properties of materials (solubility in water and

gas production with an acid) and learn how you

can use these properties to distinguish three

identical-looking white powders.

YOU WILL NEED

3 measuring cups, 3 small test tubes, chemistry

station, measuring spoon, teaspoon, powdered

sugar, corn starch, baking soda, water

HERE’S HOW

1. Have someone else put a teaspoon of

powdered sugar in one cup, a teaspoon of

corn starch in another cup, and a teaspoon of

baking soda in a third cup, so that you do not

know which substance is in which cup.

A. Water solubility test

2. Fill the three test tubes with water to a height

of three centimeters in the tube. Place them in

the chemistry station rack.

3. To each test tube, add one spoonful of one of

the three white powders, making sure you put

a different powder into each tube. Stir each

tube. Observe how the different white

powders behave in the water.

B. Gas production with an acid

test

4. Fill the three test tubes with household

vinegar to a height of one centimeter. Place

them in the chemistry station rack.

5. To each test tube, add one spoonful of one of

the three white powders, making sure you put

a different powder into each tube. Stir each

tube. Observe how the different white

powders behave in the vinegar.

WHAT’S HAPPENING

A. The powdered sugar and baking soda dissolve in

water, so that nothing can be seen. The corn starch

initially remains as lumps lying in the water and then

creates a cloudy mixture as soon as you stir it. Now

you can identify the corn starch. The starch particles

are much larger than the sugar and baking soda

particles, so they do not dissolve.

B. In the test tubes with the powdered sugar and the

corn starch, you will not observe a bubbling

reaction. The baking soda, however, reacts with the

vinegar to form carbon dioxide bubbles. Now you

can identify the baking soda. And through the

process of elimination, you know the third

chemical must be the powdered sugar. You have

identified all three substances without needing to

taste them!

› › › EXPERIMENT 14

Ooze Labs Chemistry Station

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