Home experiments

Home Experiments Three Simple experiments to get you thinking Experiment 1 Materials needed • 1cup water • ½ teaspoon sugar • Pyrex measuring jug • Microwave Oven

Experment 2 Materials needed • Celery sticks (better if have some leaf part left on some) • Coloured water ( watercolour paint or food colouring) not green.

• Vegetable peeler • 2 Glasses

Experiment 3 Materials needed • 3 Glass containers ( 1 of which needs to be Pyrex) • 3 Tea bags or a dark stock cube cut into three equal portions

Experiment 1 1. Add a cup of water to the pyrex jug.

2. Place in microwave and put on full power for 2.30 minutes.

3. Remove from microwave, the water is obviously hot.

4. Now add ½ tea spoon of granulated sugar.

What did you see happen and why do you think it happened?

Experiment 1 • Answer • You should have noticed the sudden appearance of a rush of small bubbles.

• You might think the bubbles came from air trapped in the sugar. That’s not the case, if you add sugar to cold water nothing happens.

Why? The answer is to do with the way microwaves heat water. Unlike a normal kettle the heat is not from the bottom. Its actually from hot spots within the middle of the water. When you add the sugar these hot spots cause water vapour (steam) to form, hence the bubbles.

This is why microwave ovens have defrost settings they give alternating blasts of energy followed by a period of no microwaves, allowing time for the heat to travel through the whole object. If you just heat a frozen piece of food on full power parts get heated up at the hot spots leaving other parts still frozen.

Experiment 2 • 1 Put a celery stick in half a cup of coloured water. (red food dye is best if you have it) • Gradually the water will move all the way up stem (it takes a while so check back every ½ hour or so) • Now use a vegetable peeler to shave away the outer surface of the celery.

• What can you see?

Experiment 2 • You should see that some long strands contain a lot of colouring. These strands are cell tubes called xylem. They are what carry water throughout the plant. You can see where the xylem is by cutting across the stalk with a knife. • If you have any leafy celery sticks repeat the experiment putting one stem in daylight and the other in darkness. You should find that one moves faster than the other, but why?

Experiment 3

• Setup You will need 3 glass containers (they need to be about the same size/volume) and one needs to be pyrex for hot water.

• Fill one with very cold water from melted ice cubes. Then one with tap water and the last with hot water (only use a pyrex type container for this one).

• Wait for the water to settle then using a long spoon of stick hold down a teabag or stock cube/bovril cube at the bottom. DO NOT STIR. • Leave for a few minutes then compare which ones is the colour moving through the fastest.

• Why?

Experiment 3 Why? Well all objects are made out of particles.

The more energy a particle has the more it moves. In the hot water the particles have the most energy so are moving around more and at higher speed. This causes the dye particles to spread out faster as they get hit by the water particles.