The grade 6 English science unit, Gases, meets the academic content standards set in the Korean curriculum, which state students should:

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1 This area deals with the properties of gases as small collections of particles. Different kinds of intangible and invisible gases attract students curiosity and promote their use of reasoning skills. Students define the relationship between pressure and the volume of a gas by conducting qualitative experiments and come to understand the properties of a gas as a cluster of particles. They identify the properties of oxygen and carbon dioxide by means of experiment and investigate the different gases encountered in everyday life.

2 The grade 6 English science unit, Gases, meets the academic content standards set in the Korean curriculum, which state students should: a) Understand that a gas consists of particles and be able to explain its properties. b) Recognize the relationship between pressure and the volume of a gas as being a change in the distance between particles. c) Identify techniques for producing oxygen and carbon dioxide and understand their properties. d) Investigate situations in which gases are used in everyday life and be able to explain such cases in relation to the properties of these gases.

3 It is easy to understand that solids and liquids take up space because you can see them. It is a little more difficult to understand that gases also take up space. An easy experiment to show this is by making a vortex generator, also known as an air cannon. When a person applies a force to the air cannon, you will feel the air rush pass you. You can feel it because the gases in the air are made up of particles. Adding a little smoke will help make the colorless gases visible and prove that gases do take up space. 500mL pet bottle Balloon Incense stick Lighter Scissors 1. Cut the bottom off the bottle. Then cut a balloon in half. Stretch the balloon over the bottom of the bottle. Hold the opening of the bottle to your face and gently tap the balloon. Draw a picture to show the smoke rings coming out from your air cannon. What did I learn? 2. Light an incense stick and then blow it out. Hold it inside the bottle so that the bottle fills with smoke. Don t touch the sides of the bottle with the incense stick! 3. Gently tap the balloon. Try to get the smoke coming out in a ring shape. You can try to do some tricks, such as getting a ring through another ring, as you practice. 1. What property of the gases in the air makes it difficult to know that it takes up space? 2. How did this experiment show that air takes up space? 1

4 We now know that gases take up space. We could feel the gases rush pass us as they exited the air cannon, but what volume and shapes do gases have? Let s begin by looking at solids and liquids first. A solid has a definite volume and shape. A liquid has a definite volume, but its shape changes depending on the container it s in. Now let s consider gases. A gas has no definite volume or shape. The particles of gases have the energy to move far apart from each other to take the shape of its container. Long balloon Balloon pump Particles of a solid. Particles of a liquid. Particles of a gas. 1. Use a pump to blow up a long balloon. Tie the end to stop the air from escaping. 2. Use your fingers to push the sides of the balloon and note the feeling. 3. Extra: Twist the balloon into different shapes. Practice your balloon art. Draw a picture of your best balloon shape. What did I learn? 1. What happened to the shape of the gas inside the balloon? 2. How are gases and liquids similar and different? 2

5 Gases have no definite volume and shape. The particles in gas have more energy than the particles in solids and liquids and can easily move far apart to take the shape of its container. However, the volume of gas depends on pressure. As the pressure increases, the volume of gas decreases. It can also be said that as the volume decreases, the pressure increases. In a big container, gas particles are far apart from each other, but as you start to apply pressure, the gas particles will get closer together and the volume of gas will be smaller. 50cm PVC tube 50cm dowel rod Potato Safety glasses The volume of the gas begins to decrease as the pressure increases. 1. Stab one end of the PVC tube through a potato. Turn the tube upside down and repeat this to the other side. Draw what the gas particles would look like after pushing the two potato pieces closer together. 2. Slowly push one of the potato pieces in the PVC tube with the dowel rod towards the other end until it is about a third of the way down. Before = gas particle 3. Take the dowel rod out. Then, quickly ram it back into the PVC tube. The potato piece at the end of the PVC tube should fly out. After What did I learn? Potato 1. What happens to the volume of a gas if you increase the pressure? 2. Why did the potato at the end of the PVC tube fly out? 3

6 We saw in the last activity that if you increase the pressure on a gas, its volume decreases. This activity will show that if you decrease the pressure, the volume of the gas will increase. This proves that pressure and volume are inversely proportional. 900mL storage jar Vacuum pump Marshmallows Marshmallows are made from sugar in a way that allows lots of air to be trapped in small pockets. When the pressure in the container decreases, the gas particles in the marshmallows will begin to spread and the volume will get bigger. We can decrease air pressure by using a vacuum. 1. Fill the jar with marshmallows. 2. Cover the jar and use the vacuum pump to take out as much air as you can. 3. Release the pump and observe what happens. Draw a marshmallow to show a before and after picture. Before After What did I learn? 1. What did the vacuum pump do the pressure inside the container? 2. Why did the marshmallow get bigger? 4

7 Carbon dioxide is a gas that humans are very good at making. The human body takes in oxygen from the air and passes it around the body. The cells in the body then make carbon dioxide which is breathed out. Carbon dioxide is easily made through different chemical reactions. Carbon dioxide is made when you add an acid, such as vinegar, to a carbonate, such as baking soda. The following reaction occurs; Vinegar Baking soda Rubber glove Jar Tablespoon Teaspoon Acid + Carbonate = Salt + Water + Carbon dioxide A Ziploc bag full of carbon dioxide. 1. Pour 3 tablespoons of vinegar into the jar. Add 2 teaspoons of baking soda to the inside of the glove. 2. Put the glove over the top of the jars so there are no gaps. 3. Help the baking soda from the glove drop into the vinegar. Draw a picture to show what happened. What did I learn? 1. Why did the glove inflate (get bigger)? 2. What products are made when you add an acid to a carbonate? 5

8 Carbon dioxide is a colorless and odorless gas. It makes up about 0.03% of the air. Carbon dioxide gas is made up of one carbon atom and two oxygen atoms. It is heavier than air. It is slightly soluble in water. When it dissolves in the water vapor in the air, it forms carbonic acid. This is why normal rain is slightly acidic. Fires cannot burn in carbon dioxide. However, many fuels, such as wood and coal, produce carbon dioxide when they burn. Empty pet bottle Vinegar Baking soda Candle Match A model showing that carbon dioxide is made up of one carbon atom and two oxygen atoms. 1. Mix 50mL of vinegar and half a tablespoon of baking soda together in the bottle. Wait a minute to allow lots of carbon dioxide gas to be made. 2. Use a match to light a candle. 3. Carefully pour the gas over the candle flame. Be careful not to let any of the liquid come out, as we are trying to show that the gas can put out the flame. Draw a picture to show what happened. What did I learn? 1. List 5 properties of carbon dioxide gas

9 Oxygen is the gas needed for life. Just as humans are good at making carbon dioxide, plants are just as good at making oxygen. Plants make oxygen in the process known as photosynthesis. The equation can be seen below. Sunlight + Water + Carbon dioxide = Food + Oxygen Another way that oxygen can be made is when hydrogen peroxide decomposes. This is a fairly slow process that can be sped up by adding a catalyst (a substance that speeds up reactions). Hydrogen peroxide decomposes to make water and oxygen. Empty coke bottle Hydrogen peroxide Red food coloring Detergent Yeast Water Teaspoon Tablespoon Measuring cylinder Large container Hydrogen peroxide is a hazardous substance. Take care when using it. 1. Add 100mL of hydrogen peroxide into the empty coke bottle that is placed in a container. Add a few drops of red food coloring. Add a squirt of detergent. Draw a picture to show what happened. 2. Dissolve 1 teaspoon of yeast in 2 tablespoons of water and add this to the coke bottle. 3. Stand back and see what happens. Touch the coke bottle. What did I learn? 1. How was the oxygen made? 2. What three things are needed for a plant to make oxygen? 7

10 Oxygen is a colorless and odorless gas. It makes up about 21% of the air. Oxygen gas is made up of two oxygen atoms. It is lighter than carbon dioxide. It is soluble in water. This is why sea creatures are able to survive in the oceans. For example, when a fish takes in water, it moves pass the gills which take out the oxygen so it can be used by them. Fires need oxygen to burn. Pure oxygen will make things burn very quickly and brightly. Empty pet bottle Hydrogen peroxide Yeast Water Candle Match A model showing that oxygen is made up of two oxygen atoms. 1. Add 100mL of hydrogen peroxide into the empty pet bottle that is placed in a container. Dissolve 1 teaspoon of yeast in 2 tablespoons of water and add this to the pet bottle. 2. Use a match to light a candle. 3. Carefully place the lit candle over the bubbles coming out from the pet bottle. Draw a picture to show what happened. What did I learn? 1. List 5 properties of oxygen gas

11 Most people know the chemical formula for water is H2O, but what does this actually mean? It means that water contains two hydrogen atoms and one oxygen atom. Through electrolysis (passing an electric current through a solution), it is possible to separate the hydrogen and oxygen and make hydrogen gas and oxygen gas. Hydrogen gas can also be made if you add an acid, like vinegar, to magnesium. When hydrogen is mixed with air and a burning match is put near, it will explode. In small amounts, it makes a pop. In theory, hydrogen gas is a good fuel, but it is difficult to use safely, as seen in the Hindenburg airship disaster. Test tube Test tube stopper Magnesium strip Vinegar Match The Hindenburg airship was filled with hydrogen gas and exploded. 1. Add a small amount of magnesium ribbon to a test tube. Draw a picture to show what happened. 2. Cover the magnesium with vinegar and quickly put on the stopper. Wait a few minutes. 3. Light a match. Remove the stopper from the test tube and quickly put the lit match to the opening of the test tube. Listen for a pop. What did I learn? 1. What two gases can be made from water? 2. What test can be done to show that the gas is hydrogen? 9

12 Humans use the properties of different gases in their everyday lives. You might find some of the following uses surprising. Argon is a gas used to fill the space inside light bulbs. Krypton is a gas used inside fluorescent tubes. Neon is a gas that glows red when electricity passes through it and is used in neon lights. Helium is a very light gas and is used in balloons to take scientific equipment into the sky. Nitrogen is a gas used in potato chip packets to help stop the chips getting crushed and to prevent moisture from ruining the crispness. Potato chip pack Balloons Helium 1. For nitrogen: Gently press an unopen pack of potato chips. Then, open the pack and break a potato chip in half. Eat the pack with your classmates. 2. Compare the crispness of your newly opened potato chips with ones that were open earlier that day by your teacher. 3. For helium: Blow up a balloon with your own breath. Compare it to a balloon that was blown up with helium. Draw a picture to show what happened to the balloon you blew up and the balloon filled with helium. What did I learn? 1. Why is nitrogen used in potato chip packets? 2. How is helium useful to humans? 10