070 elements mixtures compounds lab

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070 elements mixtures compounds lab Powered By Docstoc
					Name ______________________________________ Period ____________________ Date ___________________

                                          ELEMENTS, MIXTURES, AND COMPOUNDS
Background:
   Matter can be classified according to make up. Elements, mixtures and compounds are the three main groups.
Today we’ll start with two common elements. When two elements are combined, a chemical reaction does not always occur
between them. If it does not, the two elements form a mixture in which the properties of each of the two elements remain the
same. Remember, mixtures can be separated using physical properties.
   If a chemical reaction does occur, the two elements form a compound. The compound has physical and chemical
properties that are unique to that compound, often extremely different from the properties of either of the original elements.
The two elements in a compound can only be separated using chemical properties, as a result of yet another chemical reaction.
   In this investigation observe how physical and chemical properties are affected when two elements are first physically
mix and then chemically combined.

Procedure:
1. Work as a table group using cupboard materials ONLY from the cupboard you are assigned. You are expected to work
   (and stay) together and take turns doing the assigned tasks. You must wear goggles in the lab area at all times.
2. On a clean, zeroed triple beam balance, use a piece of scrap paper to measure out exactly 2 grams of sulfur powder.
3. Using another piece of scrap paper measure out exactly 4 grams of iron filings.
4. Take turns examining these materials using a magnifying glass. Compare and describe the color, size, shape and luster
   (shininess) of the individual pieces of each substance. Record your observations in the data table provided.
5. For each substance, have one partner carefully hold the paper off the counter while another partner moves a magnet
   (sealed in a baggie) underneath it. Record what you observe in the data table.
6. On a large piece of scrap paper pour both powders and mix them with a wooden splint. Make sure it is well mixed and
   uniform throughout.
7. Repeat steps 5 and 6, recording observations for the “iron-sulfur before heating” in the data table.
                                                       8. Half fill a 250-mL beaker with water and set it aside. Carefully pour
                                                          iron-sulfur mixture in a large test tube. Light the Bunsen burner. Hold
                                                          the test tube with a test tube clamp pointing the opening of the test tube
                                                          toward the back wall as you move the test tube around in the flame so all
                                                          of the contents are evenly heated. Heat the mixture for about 4 minutes.
                                                       9. Record what you observe as the mixture is heated, in the data section.
                                                       10.When you are sure there are no further changes occurring in the test
                                                          tube, shut off the Bunsen burner and immediately put the test tube
                                                          into the beaker of cold water. If the test tube does not break your
                                                          teacher will help you to carefully break it.
                                                       11. Use a pair of tweezers to remove a piece of the heated material that
                                                          looks well reacted and most uniform throughout, (avoid the broken
                                                          glass!). Place it on a piece of scrap paper and repeat steps 5 and 6
                                                          and record in the data table under “iron-sulfur after heating”.
12. Carefully put all broken glass and the heated material in the “waste” bucket on the supply table. Be sure your cupboard is
   complete and neatly arranged. Clean the area in which worked and the sink you used. Finally, wash your hands.

Data:
      Physical                   Sulfur                      Iron              Iron-Sulfur before         Iron-Sulfur after
    Properties                                                                      heating                   heating
  Color
  Shape of pieces
  Size of pieces
  Luster of pieces
  Effect of magnet
Observations during heating:
Analysis and Conclusions:

1. How did the properties of sulfur alone compare with the sulfur in the unheated iron-sulfur combination?
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2. How did the properties of iron alone compare with the iron in the unheated iron-sulfur combination?
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3. How did the properties of sulfur alone compare with the sulfur in the iron-sulfur combination after it was heated?
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4. How did the properties of iron alone compare with the iron in the iron-sulfur combination after it was heated?
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5. What kind of substance was iron and was sulfur before they were stirred together? _______________________________
6. What kind of substance was the iron-sulfur combination before heating? _______________________________________
7. What kind of substance was the iron-sulfur combination after heating? _________________________________________

Critical Thinking and Application:

1. Explain, using information from the background and your data, what supports the idea that mixing iron and sulfur together
on the paper results in a mixture of two substances. ___________________________________________________________
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2. Explain, using information from the background and your data, what supports the idea that heating iron and sulfur together
in the test tube results in a new compound composed of chemically combined iron and sulfur.__________________________
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3. Identify each of the following as an element, a mixture, or a compound (you may need to use your book, chapter 4).

a. aluminum foil _______________             b. air ____________________             c. carbon dioxide ___________________

d. salt water ___________________            e. copper wire _____________            f. steel ___________________________

g. sugar ______________________              h. a taco __________________            i. arsenic _________________________

4. Balance the following equations by adding coefficients only (no adding subscripts or adding new chemicals to the equation).

         Pb                          +                I2                                    PbI

         P                        +                  O2                                    P2O5

         CO2                     +                   H2O                                   C6H12O6             +          O2

				
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