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Can You Identify a Chemical Reaction

By Suzanne Carroll,2014-10-07 21:27
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Can You Identify a Chemical ReactionCan

    Can You Identify a Chemical Reaction?

    Teacher copy

    Materials:

    Sheets of paper

    2 Nails (one new and one rusted)

    Alka Seltzer tablet

    Small amount of salt

    Small bottle of vinegar

    Small amount of baking soda

    Small amount of citric acid

    Small bottle of milk

    A few ice cubes

    A piece of steel wool

    Plastic or glass marble

    Water

    Steel wool

    Aluminum foil

    A piece of copper wire

    Containers for mixing that can be washed out later

    1. Start out the small group lesson by reviewing the vocabulary words for the day:

    Physical property can be seen without changing the substance.

    Chemical property is the ability to change into a new substance with new properties. Chemical reaction (Chemical change) is when elements are rearranged into new

    substances. For example: Fe + S ; FeS (Mass stays the same before and after)

    Physical Change is a change in size, shape or state of matter but no new substance is made.

    Element is a substance that cannot be broken down into anything simpler.

    Compound is made up of two or more elements that chemically combine to make a new substance with new properties. It can not be broken down easily. Examples include water, salt and sugar.

    Symbol is the way to write an element using one or two letters. Ex. Fe

    Formula is the way to write a compound using symbols and subscripts. Ex. FeS

    Using a matching column, discussion or word wall, reinforce each term.

    2. Conduct the following experiments (investigations) so that students can decide whether a chemical reaction is occurring. Let students help in each activity. Emphasize the vocabulary used in the instructions. Feel free to add or remove activities if time runs short. Make sure that time is left for the TAKS-like questions. The answers are in parentheses. Ask: How can you figure out if a chemical reaction has happened? Discuss the students’ answers and start the activities.

    A. Shred or tear up a sheet of paper (No chemical reaction: Physical change)

    B. Show a new nail and a rusted nail. Scrape off the rust and decide. (Chem. Reaction)

C. Take an Alka Seltzer tablet and break it up and ground it into small pieces. (No:

    Physical Change)

    D. Take a sheet of paper and roll it into a ball. (No: Physical Change)

    E. Dissolve salt into water. (No: Physical Change)

    F. Add baking soda to a small amount of vinegar in a container. Observe gas bubbles. (Chemical Reaction)

    G. Add vinegar to milk. (Observe the precipitate indicating a chemical reaction.) If you

    would like to reinforce the idea that mass before the reaction equals the mass afterwards, this would be a good experiment to illustrate it. Find the mass of both containers of vinegar and milk on the balance and after the reaction, mass all of the products and containers. Since no gas is produced, the mass should stay the same. H. Add citric acid to baking soda and water. Observe what happens and any temperature change. (This reaction should get colder as energy is gained or taken in. This is an endothermic chemical reaction.)

    I. Add steel wool to vinegar. Observe what happens and any temperature change. (This

    reaction should get hotter as heat energy is released. This is an exothermic chemical reaction.)

    J. Drop a marble into a container of water. (No: Physical Change)

    K. Show melting ice cube. (No: Physical change)

    L. Hit a ball of aluminum foil to flatten it into a sheet. (No: Physical Change-Malleable)

    M. Show a piece of wire that was made from copper that was heated and stretched. (No:

    Physical Change-Ductile)

    N. Show the following equation to students: Al + S ; Al + S (No: The elements are not

    rearranged so this is not a chemical reaction.)

    O. Show the following equation to students: Ca + O ; CaO (Chemical Reaction of

    calcium reacting with oxygen to form a new compound)

    P. Show the following equation to students: 2 H + O ; 2 HO (Chemical Reaction 222

    showing water being made. The numbers in front of the symbols are needed to show that the mass before and after the reaction stays the same.)

    3. Give students the TAKS-like questions to answer and discuss after they are finished.

Answers: 1. D

     2. F

     3. C

     4. H

     5. B

     6. J

     7. B

    Student Sheet for Chemical Reactions Name _______________________________

    Vocabulary to remember for this topic on the Science TAKS test:

1. Physical property can be seen without changing the substance.

    2. Chemical property is the ability to change into a new substance with new properties. 3. Chemical reaction (Chemical change) is when elements are rearranged into new

    substances. For example: Fe + S ; FeS (Mass stays the same before and after)

    4. Physical Change is a change in size, shape or state of matter but no new substance is made.

    5. Element is a substance that cannot be broken down into anything simpler.

    6. Compound is made up of two or more elements that chemically combine to make a new substance with new properties. It can not be broken down easily. Examples include water, salt and sugar.

    7. Symbol is the way to write an element using one or two letters. Ex. Fe

    8. Formula is the way to write a compound using symbols and subscripts. Ex. FeS

    How can you figure out if a chemical reaction has happened?

    _______________________________________________________________________

    _______________________________________________________________________

    _______________________________________________________________________

    Any other notes that you want to take to remember what we did today:

Answer these questions based on today’s work:

    1. Which of the following is an example of a chemical property?

    A. Texture

    B. Color

    C. Hardness

    D. Flammability

2. Which of the following can indicate that a chemical reaction has taken place?

    F. Formation of a precipitate

    G. Change in the state of matter

    H. Change in shape

    J. Change in size of object

3. A chemical reaction happens when -

    A. Paper goes through a shredder

    B. The water in a bird bath evaporates

    C. Gas bubbles form when two liquids are mixed and temperature rises

    D. Ice forms after water is placed in a freezer

4. Which of the following situations contains an example of a chemical reaction?

    F. Watercolor paint drying on paper

    G. A sugar cube dissolving in a glass of water

    H. A bicycle rusting after it is left in the rain

    J. Breaking a glass cup into many pieces

    5. Which of these is an example of a chemical reaction?

    A. A pot of water boiling

    B. An iron nail oxidizing

    C. Corn being ground

    D. Sugar dissolving in tea

6. One of the reactions involved in obtaining pure copper (Cu) from copper-

    containing rock is

    CuS + O ; 2 Cu + SO 222

     Which of the following best describes the reaction?

    F. Copper atoms are used to produce more copper atoms.

    G. Compounds change phase from liquid to gas

    H. Atoms of other elements are turned into copper atoms

    J. Elements are rearranged into new substances

7. A substance that is made of elements that have chemically combined is called -

    A. Complex element

    B. Compound

    C. Mixture

    D. Alloy

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