Chemistry I Worksheet Classification of Matter Changes by skk51796


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									Chemistry        Day 010
Major Topic: Classification of Matter             Reading: Ch. 3.1 through 3.4
Focus: Students will be able to: 12PS#1, 12SWK#1,3
    define, correctly use, and differentiate among the terms and concepts of mass, elements, compounds, mixtures
       (heterogeneous & homogeneous), substances
    differentiate between & give examples of physical & chemical properties, intensive & extensive properties
    differentiate between & give examples of physical & chemical changes
    Webquest to illustrate the different types of matter.

       Molecular models to demonstrate the difference between atoms, molecules, mixtures
       elements: Fe, Al, Si, Au, S
       compounds: sucrose, NaHCO3, water, sulfuric acid
       homogeneous mixtures: sucrose in water, brass weight, vinegar
       physical changes: candle wax, paper
       chemical changes: Lycopodium powder & Bunsen burner, Mg ribbon, Zn & I2, electrolysis setup
       ½ page in-class WS (Matter: Properties & Changes)
       Classification of Matter handout
       HW WS: Matter
       2 Lab Procedures: % of Sn in Solder, Separation of a Mixture
   1. Central questions: What is matter & how is it classified? Best done with a concept map.
   2. Define matter - anything w/ mass & volume.
          a. Mass - how much stuff is in an object or sample. Already decided that mass is constant for a given
              object. Doesn’t change w/ gravity, temperature, etc.
    3. Varieties of matter - What pigeonholes or classifications can we put different kinds of matter in?
           a. Elements - All the particles (atoms) in it are of the same type (use molecular models).
                      i. All of the atoms behave the same way in the same situations (called physical and chemical
                     ii. All elements are on the periodic table - surefire method of knowing!
                    iii. Pass around samples if S. want to see them.
            b. Compounds - The particles here are molecules, made up of 2 or more atoms, of different or same types.
               Use molecular models.
                    i. All the molecules have the same set of physical & chemical properties, but they can be broken
                       down into their elements by chemical or physical means. Demo electrolysis of water and/or
                       dehydration of sugar by H2SO4 .
                   ii. Further, the properties of a compound are different than the properties of the elements that make
                       it up. e.g. sugar is C, H, O.
                  iii. Have S. name some common compounds: NaCl, H2O, CO2, sugar, etc.
                  iv. Elements & compounds are called substances.
                   v. Law of Definite Proportions or Constant Composition - The elements in a compound are
                       combined in fixed ratios. Different ratio = different compound! We can express these ratios as
                       masses (100 g NaCl has 39.3 g of Na and 60.7 g of Cl), or in moles (the ratio of Na to Cl is 1:1).
            c.   Mixtures - The particles here are of different types (Mix models together.) More than 1 type of element
                 or compound in a mixture. Sugar water, brass, air !
                       i. The different particles (both elements & compounds) have different properties (they keep their
                          own original properties.)
                      ii. Because they have different properties, the components of a mixture can be separated by
                          physical and chemical means. Let’s take two mixtures: Kool-Aid, and sand mixed in with salt.
                          Who can think of a way of separating the different components of these two mixtures? Demo:
                          sugar water.
                     iii. Because a mixture just has different stuff mixed together, it’s composition isn’t fixed. You can mix
                          Jell-O with different amounts of water: less and you get Jigglers, more = regular Jell-O
        d. Two basic types of mixtures
               i. Homogeneous - the mixture appears uniform throughout (brass, solutions of salt or sugar in
                  water, etc.)
                               a. Solutions – one substance dissolves into another substance. There is only one
                               b. Colloids – This is actually a suspension, but the particles are so small that they
                                   will not settle, even over long time periods. Milk is an example, as are fog, and
                                   cigarette smoke in air. Colloids disperse a beam of light that is passed through
                                   the colloid. This is called the Tyndall Effect. Demo with laser and chalk dust in



                ii. Heterogeneous - the mixture isn’t uniform, has pieces or discrete regions in it. (Piece of granite,
                    cottage cheese, etc.)

4. Properties - How are you going to classify different stuffs, what criteria will you use? Anything about the
   material that you can detect and measure, how the stuff behaves in different situations. Pick a student - what
   properties does he or she have?
       a. Color, appearance, odor, taste, the phase of the substance (solid, liquid, gas), whether it’s flammable or
           explosive, density, mass, volume, reactivity to acids or bases, etc.
       b. Some of these properties depend only on how much of the stuff you’ve got. These are called extensive
           properties. Which of these are extensive? Mass, volume, weight.
       c. Some properties depend on the identity of the substance - these are intensive: all the other properties.
           Intensive properties are really useful, because they can be used to identify a substance.

5. Now we have a list of properties. There’s another way we can classify properties, so that we can classify
   substances: That’s by deciding whether a property is chemical or physical.
      a. Physical properties - any characteristic of a substance that you can observe in some way, without
          producing a new substance. What examples can you think of for physical properties? (Color,
          appearance, luster, odor, taste, feel, texture, surface area, hardness, ductility, malleability, density,
          melting point, and boiling point.)
      b. Chemical property - any characteristic of a substance that allows it to react with or be inert with another
          substance. What examples can you think of for chemical properties? (reactivity, explosivity (like TNT),
          and sensitivity to shock (like nitroglycerin). Non-reactivity is also a chemical property. Glass is non-
          reactive to most strong acids.)
6. Physical and Chemical changes.
      a. Physical Changes - the outer form or condition of a material changes, but no chemical reaction has
          occurred and no new substance has been produced.
               i. Examples? Phase changes, eating & chewing food, a chunk of something being ground to a
                  powder, condensation, crystallization, freezing, and the magnetization of certain metals. Demo:
                  melt & recrystallize wax, on finger!

       b. Chemical Changes - the substance reacts in some way to produce a new substance. (Chemical bonds
          have been broken and different ones formed - atoms have re-arranged).
              i. Examples? digestion of food, combustion of wood, paper, gasoline, photosynthesis, clotting of
                 blood, etc.
                     a. Demo sugar & sulfuric acid (IN HOOD OR WINDOWSILL !!)
                     b. Demo Lycopodium spores into a flame.
                     c. Demo burning Mg ribbon
                     d. Demo NaHCO3 + vinegar in big grad cyl. Put out candle flame.
                     e. Demo Zn + I2 + water (small amount!)

7. The only math skill of the day: Determining the % of an element in a compound from the masses of the elements.
   Sugar contains the elements C, H, O. A 50.00 g sample of sugar contains 20.00 g C, 3.33 g H, and 26.67 g O.
   What is the % of each element in the sample? Show how. If the sample size were increased to 150.00 g, how
   much mass of each element would there be? What would the % of each element be in sugar imported from
   South America? The same. Remember Law of Definite Proportions.

8. Go over WS in class.
9. Hand out Infoquest. Due Friday (if assigned Monday).
10. EVALUATION - through responses on HW, Infoquest, and on tomorrow’s lab.
Name:                                                                                                       / ?? pts

                                              Chemistry Worksheet: Matter

1. Classify as (E)lement, (C)ompound, or (M)ixture:
        a) ____ water          b) ____ milk               c) ____   CO2                d) ____ vinegar
        e) ____ mercury        f) ____ dilute HCl         g) ____   sulfur             h) ____ molasses
        I) ____ sugar          j) ____ Na2CO3             k) ____   soil               l) ____ sodium
        m) ____ tungsten       n) ____ sea water          o) ____   C6H6

2. Classify as either a (C)hemical or (P)hysical change:
        a) ____ wax melts                 b) ____ photosynthesis             c) ____   water evaporates
        d) ____ water boils               e) ____ milk turns sour            f) ____   mercury expands in a thermometer
        g) ____ silver tarnishes          h) ____ a wound heals              i) ____   coal is converted into nylon
        j) ____ teeth get cavities        k) ____ a candle burns             l) ____   water freezes
        m) ____ sharpening a pencil       n) ____ a He balloon floats        o) ____   food is digested

3. The compound glycerol is composed of C, O, and H. When a 35.50 g sample of glycerol is analyzed, it is found to
        contain 13.89 g of C, 18.52 g of O, and the rest is H. (Show your math.)

a) Determine the % of C, H, and O in glycerol.

b) What is the % (not the mass) of C in a 200 kg sample of glycerol?

c) Another sample of glycerol is tested. What will the % of O be in it?

d) How many grams of C are there in a 250.0 g sample of glycerol?

4. Give an example of:
a) a “substance”: __________________________
b) a homogeneous mixture _________________________
c) a heterogeneous mixture _____________________________
d) a chemical property __________________________________

5. ______________ What is the mass of 2.0 kg of Au when the gold is taken to another planet having 3X the gravity of
Your name: _________________________              Your lab partner:                                                   / 50 pts

                                    Classification of Matter Chemistry Infoquest
                          You will need both your book and access to the Internet for this exercise.

The science of chemistry is the study of how matter behaves when it comes into contact with other forms of matter or with
the various forms of energy (heat, light, electricity, etc.) The term “matter” is extremely broad, meaning anything that has
both mass and volume. It’s tough to define “mass” without reference to matter, but we’ll try: mass is the ratio of the force
applied to move an object divided by the acceleration that the applied force produces. Sound complicated? Not really; it’s
just Sir Isaac Newton’s second law of motion: Force / acceleration = mass.

Is mass the same thing as weight? No!! The weight of an object is really the downward force that is produced by the
mass of an object being accelerated by gravity. If an object is taken into space, it no longer has weight, but its mass is
still there! If you wanted to move a weightless astronaut, you’d still have to give him a pretty hefty push (force) to get him
moving, even though he weighs nothing.

For chemists, the most important way to classify matter is into elements, compounds, and mixtures.
     Use either your chemistry book, a dictionary, or search online to find a definition for each of the following terms.
           o element

            o   compound

            o   mixture

            o   substance

            o   atom

            o   molecule

Elements: Chemists have determined that all the atoms of a given element are similar in structure and behave the same
      way in any given situation. Not all atoms of an element are completely identical, however. For 2 atoms to be of
      the same element, they must have the same number of positively-charged protons. For an electrically neutral
      atom, the number of protons must equal the number of negatively-charged electrons. However, the number of
      neutrons, which have no electrical charge, is allowed to vary. Atoms of the same element which have different
      numbers of neutrons are called isotopes.

       Go to the website Choose any element and record the following properties:
           o Element
            o   Symbol
            o   Number of protons (atomic number)
            o   What isotopes exist for this element?
            o   Where is the element found or how is it produced?
            o   What chemical family is the element in? (What is the name of the region or column of the periodic table
                that it lies in?)
            o   What commercial or medical uses does the element have?
Compounds: When 2 or more atoms (same kind or different kinds) chemically bond together, a chemical compound is
     produced. All the molecules of a chemical compound have the same set of physical and chemical properties, but
     these properties differ greatly from the properties of the atoms that make up the compound. For example,
     common sugar, sucrose – a white tasty crystalline solid, is made of carbon (a black powdery solid like soot),
     hydrogen (a colorless gas), and oxygen (another colorless, odorless gas).
       Compare the properties of table salt, NaCl or sodium chloride, with the properties of Na and Cl individually.
                                 state of matter
                                                            o                       o                      3
                                 at room temp melting point, C        boiling point, C     density, g/cm
            o   Sodium

            o   Chlorine

            o   NaCl

       Besides NaCl and sucrose, list 4 other chemical compounds, either by name or formula.

       ____________________       ____________________         ____________________         ____________________

More about compounds: We know that compounds can be broken down (decomposed) into their atoms by chemical
       reactions or by physical means (heating or electricity). It was just this ability to break down that an English
       chemist, John Dalton, used to find the formulas of a great many chemical compounds. Dalton and another
       chemist, Joseph Gay-Lussac, came up with the Law of Definite Proportions (sometimes called the Law of
       Constant Composition.) The law states that the elements in a compound are always combined in a fixed ratio of
       atoms. For example, a molecule of water always has 2 H’s and 1 O: H 2O. A molecule that has a different ratio of
       H to O is a different substance. For example: H 2O2 is hydrogen peroxide, not water.

        Below is a diagram of the decomposition of water into hydrogen and oxygen gases by an electric current. The
        process is called the electrolysis of water.

       Find out some information about John Dalton.

            o   What is Dalton’s date of birth?

            o   What city was he born in?

            o   At what university did he teach?

            o   Besides chemistry, Dalton was also interested in what other studies?
Mixtures: When different kinds of elements and/or compounds are combined together without reacting with one another,
       a mixture is formed. The different substances (components) in the mixture each keep their own original
       properties, although the mixture as a whole may have a different set of properties from any of the separate
       substances. We can use the fact that the different substances in a mixture have different properties to separate
       the components of the mixture. Mixtures may also be made in varying proportions. You may choose to put a
       whole cup of sugar in Kool-Aid, or only ½ a cup.
       Use your book, a dictionary, or search online to define the following processes:
           o distillation

            o   filtration

       There are other methods of separating mixtures besides the 2 you just defined. How might you go about
           o iron particles from sand?

            o   gold particles from sand?

            o   water vapor from air?

More about mixtures: Mixtures come in several varieties. Heterogeneous mixtures are mixtures with “chunks”.
       Cottage cheese, blood (cells + plasma), and gravel are heterogeneous mixtures.
       Give 1 more example of a heterogeneous mixture:

There are also homogeneous mixtures. These appear as if they were composed of one material, even though there are
really 2 or more components. Examples might be sugar water, air (nitrogen + oxygen + other gases), or brass. Yes,
brass is a solid solution of copper and tin that have been melted together and allowed to cool. You can see that
homogeneous mixtures can be solids, liquids, or gases.
       Use your book, a dictionary, or search online to define the following terms related to homogeneous mixtures:
           o solution

            o   alloy

            o   amalgam

            o   tincture

            o   colloid

       List 2 more examples of homogeneous mixtures.

Physical and Chemical properties: We have been thinking about and using the properties of substances to classify
       them. Properties can be either physical or chemical. They can also be intensive or extensive.
   Physical properties are those properties of a substance that you can observe or measure, without producing a new
    substance: Color, odor, taste, etc.
   Chemical properties are those properties which describe how a substance reacts with other substances or with
    energy: reactivity and its opposite inertness, explosivity, sensitivity to shock (think nitroglycerin !!)
   Extensive properties are those which just describe the quantity of a substance: mass, weight, volume, etc.
   Intensive properties are those which help you identify a substance: density, atomic mass, etc. For example: boiling
    point is both an intensive and a physical property of a substance.
      Define the following terms related to physical and chemical properties:
           o luster

           o   hardness

           o   malleability

           o   ductility

Physical and Chemical Changes: Substances can also undergo changes in both form and in chemistry.
 Physical changes are when the outer form or condition of a material changes, but the material’s chemical composition
   doesn’t change. Examples are: water freezing or boiling, food being chewed, candle wax melting, paper being torn.
 Chemical changes occur whenever a new substance is being produced. This means that the chemical bonds in a
   substance have been broken and new bonds have been formed – atoms have rearranged themselves into new
   compounds. Examples: digestion of food, combustion of candle wax, photosynthesis, clotting of blood, etc.

      List 2 physical changes and 2 chemical changes that might be made to happen to an ordinary iron nail.

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