Odors Aloft - OMSI

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  • Odors Aloft E 19 Chemistry in the K8 Classroom Grades K8 2007, OMSI

    Odors Aloft

    Learning Objectives: Students infer the presence and motion of scented molecules.

    SNEAK PEAK inside

    Advance Preparation Set Up Activity Clean Up

    20 minutes 5 minutes 20 minutes 2 minutes

    GRADE LEVEL

    K8

    SCIENCE TOPICS

    Atoms and Molecules Techniques

    PROCESS SKILLS

    Describing/Defining Inferring

    Evaluating

    GROUP SIZE

    12

    TIME REQUIRED

    ACTIVITY Students smell balloons filled with different scents to guess whats inside. STUDENT SUPPLIES see next page for more supplies balloons scent substances (extracts, etc.) string, etc. ADVANCE PREPARATION see next page for more details

    Fill balloons with scents Label balloons Blow up and tie balloons, etc. OPTIONAL EXTRAS DEMONSTRATIONS How Chemists Smell (p. E - 23) Modeling States of Matter (p. E - 23) Molecule Size and Diffusion (p. E - 24)

    EXTENSIONS Odor Diffusion (p. E - 29) Extract Essential Oils (p. E - 30)

  • Odors Aloft E 20 Chemistry in the K8 Classroom Grades K8 2007, OMSI

    Item Amount Needed

    balloons 1 per scent used permanent marker 1 per class

    straw, pipette, or eyedropper 1 per class (washing out between uses) or 510 disposable

    A selection of odor substances, for example:

    anise extract, vanilla extract, coffee extract (or very strong coffee), almond extract, peppermint extract, lemon extract, root beer concentrate, imitation chocolate flavor, imitation orange flavor, cinnamon, curry powder, ground cloves or clove oil, aftershave or perfume, baby lotion or baby powder, camphor- or eucalyptus-containing compound, e.g., Mentholatum or Vicks VapoRub Other nontoxic spices, extracts, or strong smelling substances with which the students may be familiar

    12 teaspoons of spice powder or teaspoon of liquid extract (depending on the strength of the extract) per class

    For Extension or Demonstration supplies, see the corresponding section.

    Supplies Preparation Odor Balloons

    Assign a number to each odor you will use. Use the same number for all balloons with the same odor. Fill the uninflated balloons with an odor substance. Be careful not

    to spill the odor substance on the mouth of the balloon. (See illustrations on the following page.) 1. Collect some of the odor substance (less than 1 tsp for liquid

    extracts, 12 tsp for spice powders) using a straw, a pipette, or an eyedropper. Use your finger on the top of the straw to trap both liquids and solid powders in the bottom.

    2. Insert the straw, pipette, or eyedropper into the mouth of balloon #1.

    ADVANCE PREPARATION

    SUPPLIES

  • Odors Aloft E 21 Chemistry in the K8 Classroom Grades K8 2007, OMSI

    3. Release the contents into the balloon. (NOTE: this technique even works to transfer powders, if you are careful. Alternatively, use the end of the straw to scoop the powders and transfer.)

    4. Remove the straw, pipette, or eyedropper. 5. Smell the ballooncan you smell some of the odor leaking out?

    If not, add slightly more spice or extract. 6. Blow up the balloon and tie it closed. Be careful not to let the

    balloon deflate until it is tied closed. 7. Using a permanent marker, number the balloon to match the

    odor numbers you choose. (You may choose to use the same odor more than once.)

    8. If you are using a reusable eyedropper, clean the eyedropper to completely remove the odor by rinsing the dropper well with hot, soapy water, then with plain hot water several times.

    9. Clean the mouth of the balloon if any odor substance was spilled onto the outside of the balloon.

    Repeat steps 19 for each odor.

    Notes and Hints For most substances (except weak smelling extracts, such as

    almond, and older extracts), the balloons can be prepared the morning before the activity. However, the activity works best when the balloons have been freshly prepared.

    If you prepare the balloons ahead of time, do not store them next to each other (for instance, in a large box or bag)the odors will escape from each balloon and pass into other balloons (especially peppermint extract).

    If you use a straw, dip the bottom end of your straw about 1 inch into the odor substance, then hold your finger over the top of the straw until the straw with the odor substance is inserted into the balloon. When you release your finger from the straw, the odor substance will drop into the balloon.

  • Odors Aloft E 22 Chemistry in the K8 Classroom Grades K8 2007, OMSI

    For each station 12 numbered scent balloons

    What are molecules? What are atoms? Atoms are the tiniest bits of matter, i.e., what you get upon chopping matter as small as possible. The Greek word atomos means indivisible. Molecules are atoms connected together into larger arrangements. Both atoms and molecules are much too small to see, even with a microscope. If individual atoms are tiny and invisible, why do people think they exist? What evidence do we have that tiny, invisible things like atoms exist? Atoms arent visible through regular microscopes, although scientists have seen atoms with powerful electron microscopes in recent years. Microscopes do show that there are many things in the world too small for people to see with their eyes (dust mites, bacteria, etc.). Some students might point out that we can feel invisible air moving (it pushes us fairly hard in a windstorm). This air must have weight (mass), even though we cant see it. Collect student answers, discriminating between inferences (conclusions based on evidence) and the actual evidence. Today we are going to use our bodies to collect information about how small molecules are, as well as about how they move around. FOR GRADES 38 Who can tell me the differences between solids, liquids, and gases? A solid is hard, it keeps its shape. A liquid is fluid and takes the shape of its container. A gas has no fixed shape and expands constantly. Are solids, liquids, and gases all made of atoms or molecules? If you think so, why? If not, why not? Students might point out that each substance can be divided into smaller and smaller parts, so that, logically speaking, such a cutting process would eventually produce atoms or molecules. Students might know that atoms and molecules have mass, and that solids liquids and gases have mass.

    INTRODUCING THE ACTIVITY

    SETUP

    Let the students speculate before offering answers to any questions. The answers at right are provided for the teacher. Choose questions that are appropriate for your classroom.

  • Odors Aloft E 23 Chemistry in the K8 Classroom Grades K8 2007, OMSI

    Although solids, liquids, and gases are all made of atoms or molecules, this can be hard to prove. Indeed, it was only in modern times that visual evidence (e.g., pictures) of atoms and molecules was first produced. Lets talk about air, a mixture of gases. If you blow up a balloon and then leave it for a couple days, what happens? Why do you think this happens? The balloon shrinks because the air gets out. If air can get out, it must be made of pretty small particles. In fact, the air molecules are small enough to fit between tiny, invisible holes in the walls of the balloon and escape. In the activity, students will observe balloons that are filled with smelly solids and smelly liquids. Somehow the smell gets outside of the balloon (the molecules of the solids and liquids evaporate and become gas molecules, which then escape through tiny pores in the balloon).

    How Chemists Smell Since this activity uses the sense of smell, you may wish to demonstrate how chemists smell things in a lab. They never stick their noses next to an unknown chemical and inhale, because sometimes chemicals have harmful or toxic fumesor they just stink. To smell unknown substances in the lab, chemists hold open containers away from their noses and use their hands to gently wave a small amount of the substance toward their noses. (Demonstrate this action.) Modeling States of Matter Students play a game to illustrate how molecules behave in the three states of matter. Demonstration Put students in one large group and have them link arms. Each student

    is a molecule. Their linked arms represent the attractive forces between molecules.

    First students will imitate a solid. Have them link arms very tightly and squeeze in close together. They are able to move a little but not much because the molecules are so close together. Jumping up and down, bending side to side, and twisting back and forth are all allowed, but not unlinking arms.

    Next, students become a liquid. Changing from a solid to a liquid is called melting. Students hold hands and move farther apart from each other. Occasionally they can switch and hold hands with someone new. They can move more easily but are still bound together. Notice how the molecules have expanded to fill more of the room.

    TEACHER DEMONSTRATION

  • Odors Aloft E 24 Chemistry in the K8 Classroom Grades K8 2007, OMSI

    Next, students imitate a gas. Changing from a liquid to a gas is called boiling. Gas molecules move much more quickly and each molecule acts on its own. The students let go of their classmates and move in straight lines across the room, until they run into something and bounce off of it. They then change directions. Notice how students quickly expand to fill the entire room. (If you are brave, remind students that they can still jump, bend, and twist while they are gases!)

    Have students go back to being a liquid. Changing from a gas to a liquid is called condensing. Students should move more slowly a