Thames & Kosmos Ooze Labs: Chemistry Station handleiding

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Handleiding

Oil and water

YOU WILL NEED

Small measuring cup, large measuring cup,

spatula, tall wide test tube with lid (optional), olive

oil or vegetable oil, water, liquid dish detergent

HERE’S HOW

1. Use the small measuring cup to measure out 30

ml of water. Pour it into the large measuring cup.

Then measure out 30 ml of oil and pour it into the

large measuring cup. What do you notice about

how the oil and water interact?

2. Use the spatula to mix the oil and water together.

Pour the mixture into the tall wide test tube,

screw on the lid, and shake it vigorously to mix

it. Then let the liquid sit for 30 minutes. Observe

what happens to the oil and water.

3. Open the test tube. Add a few drops of liquid dish

detergent to the oil and water mixture. Screw

the lid onto the test tube again and shake the

contents until the oil and water appear to be

mixed. What do you observe happens to the oil

and water now?

WHAT’S HAPPENING

Oil and water do not mix because water molecules are polar

while oil molecules are nonpolar. Polar means that one side of

the molecule has a slight positive charge while the other has a

slight negative charge. Water is polar because the oxygen atom

is much larger than the hydrogen atom, and pulls the negative

electrons toward itself. This influences the way that water

interacts with other molecules.

Unlike water, oils are nonpolar. This is because oils have long chains of carbons and

hydrogens, which don’t have different positively and negatively charged ends like water.

The oil and water are able to stay mixed when you add the dish detergent because the

detergent acts as an emulsifier. An emulsifier makes it so that the water and oil are able to

mix on a molecular level. This ability of detergent is what allows it to dissolve oily dirt

particles, like greasy food stuck on a dish, in water so that they can be washed away.

› › › EXPERIMENT 10

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