Gassy Class Category: Chemistry Type: Class Experiment (60 min class) Materials: 2 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 Plastic Syringes Small length of plastic tubing Block of dry ice Plastic cup Pair of disposable gloves Bottle of food coloring Water Wok or frying pan Heating plate Large plastic bag Vacuum cleaner Cardboard tube Plastic bottles Plastic cork Plexiglass safety shield Large length of plastic tubing Large juice container Small length of hard plastic tubing Dish liquid or liquid soap Warning: Dry ice must be handled with care. Always use gloves or tongs when handling! How To: Introduction: The class starts with a discussion about air. Questions to discuss are: What is air? What does it do? How does it change? Is all air the same? And how do we use it? Part 1: Attach 2 plastic syringes to a small piece of plastic tubing. Make sure one plunger is pushed all the way in and the other is pulled all the way out. © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. What happens if you push on the plunger that is pulled all the way out? Can both be pushed in at the same time? Play with the syringes and note any other interesting things that happen. Part 2: The “Kid Crusher”. Have a volunteer stand in a large plastic bag, one that will come up to their neck. Place the end of the vacuum hose in the cardboard tube and have the volunteer hold it in the bag. © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Hold the bag tight at the top and turn the vacuum on. Can they move their arms? Can anyone describe what is happening? Part 3: Gases. What happens when water is poured into a hot pan? Have they watched at home when someone is cooking? What does the class see? What kind of matter is steam -­‐ solid, liquid or gas? Dry Ice Explosion! This is something that should only be peformed by a teacher in a class and not at home! Dry ice will freeze the skin on your hands, just like a burn. A safety shield and gloves are needed. © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Discuss the properties of dry ice. Break the block of dry ice into small pieces using a hammer. Pour water into the bottle to the level shown. Drop a small handful of dry ice pieces into the bottle. Cork the bottle and place it behind the safety shield. This experiment can be performed on a smaller scale. Dye the water with a couple of drops of food coloring. What do you see happen to the cork and bottle? © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Place some dry ice in a plastic cup and pour water on top. What happens? How would you describe the white cloud pouring out of the cup? Slide a glove over the top of the cup -­‐ make sure the glove is pulled down over the lip of the cup. Wait a few minutes to see what happens. The glove pops off! Why does this happen? Using gloves remove the ice from the cup. What do you see? Is it all dry ice, or is there something else there? What has happened? Part 4: Dry Ice Bubbles. Pour some dish soap into a plastic bottle. © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Break up some dry ice and place it in the bottle. Drill a hole in the lid of a large bottle to just fit a short, large, hard tube. Tape a long piece of rubber tubing into the short piece. Pour some water into the bottle. Screw on the lid and shake the bottle. There’s not much water in the bottle. What will happen? What comes out of the tubing first? Then we have lots and lots of soapy bubbles. Why does this happen? Remember we only put a small amount of water in the bottle! © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Fine Points: The syringes experiment can also be performed with water, or with a single syringe and no tubing. Emphasize that the bottle dry ice explosion should not be performed at home. Never use glass containers for the dry ice bomb! Emphasize that the “kid crusher” experiment should only be performed when an adult is present. Big kids and adults can do the “kid crusher” activity by getting a giant leaf bag and then sitting down inside of it with knees up to chin. → The dry ice bubbles experiment can also be performed using a tall glass or graduated cylinder. → Place the container used for the bubbles experiment in a plastic tray to catch all the bubbles. →
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Objectives: During these experiments students will understand that: 1. Different states of matter exist. 2. Materials can change from one state to another, and be able to give examples. 3. That air is all around us and pushes down on us (air pressure). Concepts Involved: •
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The three most common states of matter that we encounter on a daily basis are solid, liquid and gas. All materials can change from one state of matter to the others. Even though air is invisible, it still has weight and takes up space. Air pressure is the force that air exerts on a certain area. Atmospheric pressure is the air pressure at a given place due to the weight of air in the atmosphere above. Sublimation is the transformation of a material from solid state to gaseous state without passing through an intermediate liquid state. Dry ice is so named because it doesn't melt into a wet liquid, but rather sublimates straight into the gas state. Focus Questions: 1.
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What properties does air have? Why is dry ice called dry ice, and how is it different than water ice? What are examples of the three states of matter? Describe some examples of transitions of states of matter happening on a daily basis? Elaboration: Part 1: Introduction. We are not surrounded by empty space. Air is all around us. Wind, hurricanes, and tornados are all example of air moving, and evidence of something we can’t see. Air has a mass and a volume, and pushes down on us all the time. It pushes down because gravity is pulling on it. There is about 100miles of atmosphere above sea level, pushing down on us all the time. We don’t notice it because we’ve always lived with it. Part 2: Air Pressure. It is difficult to push both syringes in at the same time because of the air that is inside the syringe. Air has volume and if we reduce that volume, we are raising the density of the air, compressing the molecules of air. This compressed air pushes back. A push is a force, and a force over a given area is a pressure. Air occupies space. In the “kid crusher,” we started with a bag filled with air. The vacuum cleaner pulled the air out of the bag and resulted in a situation where the air pressure outside the bag © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. was greater than that inside the bag. The air pressure outside the bag then pushes on the bag from all sides. Since the kid is in the bag, the kid gets pushed on too. Step 3: Focus on gases. Boiling water is something we see all the time. It is water changing from liquid state to gas state. The steam you see coming up out of the water is actually tiny droplets of water in the liquid state. They’re all hot, so they’ll soon be moving on to the gas state. This is the same situation in a cloud. It is actually not gas, but tiny droplets of liquid. At the same time, you know that these droplets, that is, the entire cloud, is surrounded by water gas. Water gas is transparent, just like the nitrogen, oxygen, argon, carbon dioxide and other gases in air, so you’ll never see it. If you put water in the freezer, it changes to solid state. Dry ice is solid carbon dioxide. When dry ice is exposed to warm temperatures it doesn’t melt, instead it turns directly into carbon dioxide gas. This process is called “sublimation” and is defined as the transformation from solid state to gaseous state without passing through liquid state. When you put a piece of dry ice on the table, it creates a little cloud around itself. Remember that the gases present – air, carbon dioxide, and water vapor – are all transparent. The cloud is visible because it is made of tiny water droplets. These droplets came from the humidity in the air. When it got cooled fast by the dry ice, the water changed states from gas to liquid and formed a lot of tiny droplets. When you drop a piece of dry ice in a bucket of water, it creates a big cloud. It does this because as it sublimates, it creates big bubbles of carbon dioxide in the water which rise to the top and stir up the water. A lot of the water gets vaporized by this stirring action, so the humidity near the surface is high. Since the carbon dioxide gas is still quite cold, it condenses the water into many little droplets making the cloud. Condensation is the opposite of evaporation; it’s a change in state from gas to liquid. The cloud is perfectly safe to touch and feel, just make sure no one touches the ice at the bottom of the cup. In the dry ice bomb activity, the dry ice warms inside the bottle and sublimates to a gas. Thus the amount of gas inside the container increases. The bottle cannot expand much, so the pressure builds up resulting in the cork exploding out of the bottle or the glove popping off the cup. During this experiment another thing that the class may notice is that at first the glove rapidly fills with gas and pops off but after a while the process will slow down. The bubbling slows because the water has become colder. When the water is cold enough, water ice will form an insulating shell around the dry ice. We use food coloring in the water to help the class see the difference between the two types of ice. Part 4: Dry Ice Bubbles. Instead of just using the dry ice in water to make a cloud, this can be taken one step further using dish soap to make bubbles. During sublimation, the soap in the water traps the carbon dioxide and water vapor inside the bubbles. The bubbles will climb out of the bottle of warm, soapy water and explode with a burst of "smoke" as they crawl out of the tube. Links to k-­‐12 CA Content Standards: Grades k-­‐8 Standard Set Investigation and Experimentation: Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other strands, students should develop their own questions and perform investigations. © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Grades k-­‐12 Mathematical Reasoning: 1.0 Students make decisions about how to approach problems: 1.1 Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and observing patterns. 1.2 Determine when and how to break a problem into simpler parts. 2.0 Students use strategies, skills, and concepts in finding solutions: 1.1 Use estimation to verify the reasonableness of calculated results. 1.2 2.2 Apply strategies and results from simpler problems to more complex problems. 1.3 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables, diagrams, and models, to explain mathematical reasoning. 2.5 Indicate the relative advantages of exact and approximate solutions to problems and give answers to a specified degree of accuracy. 3.0 Students move beyond a particular problem by generalizing to other situations: 3.1 Evaluate the reasonableness of the solution in the context of the original situation. 3.2 Note the method of deriving the solution and demonstrate a conceptual understanding of the derivation by solving similar problems. 3.3 Develop generalizations of the results obtained and apply them in other circumstances. Grade 1 Standard Set 1. Physical Sciences Materials come in different forms (states), including solids, liquids, and gases. As a basis for understanding this concept: 1.a. Students know solids, liquids, and gases have different properties. 1.b. Students know the properties of substances can change when the substances are mixed, cooled, or heated. Grade 3 Standard Set 1. Physical Sciences Energy and matter have multiple forms and can be changed from one form to another. As a basis for understanding this concept: 1.e. Students know matter has three forms: solid, liquid, and gas. 1.f. Students know evaporation and melting are changes that occur when the objects are heated. Grade 5 Standard Set 1. Physical Sciences. Elements and their combinations account for all the varied types of matter in the world. As a basis for understanding this concept: 1.g. Students know properties of solid, liquid, and gaseous substances, such as sugar (C6HO6), water (H2O), helium (He), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2). Grade 8 Standard Set 3. Structure of Matter Each of the more than 100 elements of matter has distinct properties and a distinct atomic structure. All forms of matter are composed of one or more of the elements. As a basis for understanding this concept: 3.d. Students know the states of matter (solid, liquid, gas) depend on molecular motion. 3.e. Students know that in solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently. © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included. Grade 9-­‐12 Standard Set 4. Gases and Their Properties The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. As a basis for understanding this concept: © 2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using ODC content, images, or videos, credit MUST be included.