Stabroek News Sunday

- Hello Boys and Girls,

How was your past week? Time is really flying! We are already nearly at the end of February. How were your Republic celebratio­ns at school? Did you participat­e? How many years is it since Guyana became a republic is Guyana?

Do ensure that you always use your time wisely. Be balanced: do your chores at home, revise, read, play, look at the television, sleep. Each of these is important.

Last week we looked at air. How much do you remember about air?

Put True or False for each statement that follows

1. Air is found only in some places around us . ................

2. Air can be found even in an empty glass . ................

3. We can know that air moves when we see the leaves of a tree moving . ............

4. We can see air.

5. Air occupies space .

Call up a friend and compare your answers. Did you get F T T F T (#1 5)?

This week we will continue our study of air. Let us do a simple experiment to find out more about air.

Things you need –

√ A large bowl of water

√ Two jam jars i. ii.

Fill one of the jam jars (jar 1) with water and lower it onto its side into the bowl so that at stays full of water.

Push the other empty jar (jar 2) upside down, straight down into the water so that it stays full of air.

iii. Now bring the necks of the two jars close to each other. See if you can pour the air from jar 2 to jar 1.

Did you see the bubbles of air go into jar 1, and push the water out of the way?

As the air leaves jar 2, there will be space for water to run into it.

Try it again. ................ ...............

Now see if you can end up with air in jar 1 and water in jar 2.

Does air have mass (‘weight’)? What do you think? Let’s find out. You will need –

- Two balloons

- A long thin stick i. Two similar tins A pencil A pin String Scissors

Blow up the balloons so that they are the same size.

ii. Tie the necks with pieces of string of the same length, and then tie the strings to the ends of the stick.

iii. Balance the stick and the balloons on the tins and pencil as shown in the picture. Make sure that the balloons are at the same level.

iv.

Now punch the pin into one of the balloons. What happens?

Did you hear a bang as the air rushed out? The burst balloon has lost most of its air. Did the balance tip over? The full balloon is heavier. The balloons themselves are the same, so it is the air inside the balloon that has mass,

## Air has mass!

Let’s look at the compositio­n of air and, air and burning.

Of what is air composed? Yes, air is really a mixture of invisible gases. Can you name one of these gases? Oxygen is one of the important gases in the air. It makes up 21 percent (21%) of the air. Oxygen is needed in respiratio­n and for burning. Can you suggest other uses? Nitrogen is another gas that is found in the air. It takes up about 78 percent of the air. It is the most common gas in the air. It is important in the making of ammonia used in fertilizer­s.

Have you ever heard of the gases, neon and argon? They are sometimes called rare gases because they are not found in large amounts in the air. They are used to fill electric light bulbs and advertisin­g signs. I’m sure that you’ve heard of helium balloons. It is a very light gas that is often used to fill weather balloons which are sent up in the air t o record weather changes.

Carbon dioxide is another gas found in the air. It forms only a very small part of the air around us. Carbon dioxide is forced into drinks to make then fizzy. Water vapour is also found in the air.

So we have learnt that oxygen makes up approximat­ely 21% of the air, nitrogen 78%, and the other gases only 1%.

1. What is air?

2. Name four gases found in the air.

3. Which gas is most common?

4. In many electric light bulbs the gases, ________________ and

_______________ are put.

5. Find these words in the word search following

Ammonia oxygen helium

Fertilizer carbon argon

Air dioxide neon

Gases nitrogen fizzy

Turn to 6B