Observing a chemical reaction

Objective:

Ø      To learn how qualitative and quantitative observations of a chemical reaction are used to formulate a hypothesis.

Procedure:

Ø      As you perform the experiment, record your observations in Data Table 1.

1.     Obtain and describe a sample of copper (II) chloride dehydrate, CuCl2 * 2H2O crystals.

2.     Fill the 100-mL beaker about one-fourth full with distilled water. Without stirring, add 1 level teaspoonful of crystals to the water. Record your observations of both the crystals and the water.

3.     Use the glass stirring rod to stir the mixture until the crystals are completely dissolved. Record your observations of the solution.

4.     Place the thermometer in the copper (II) chloride solution and record the temperature. CAUTION: observe the mixture from the side; do not look directly down into the beaker. Place a loosely crumpled ball of aluminum in the solution and record your observations. Stir the mixture occasionally and observe for at least 10 minutes. Record any change in temperature.

5.     Follow your teacher’s instructions for proper disposal of the materials.

Observations:

Questions:

2.  List each of your observations in one of four following sections. Number your observations consecutively. Circle the number of any observation that is quantitative.

          A. observations of dry crystals:

          B. observations of wet crystals before stirring:

          C. observations of the solution before addition of aluminum:

D. observations of the reaction that occurs when the when the aluminum is added to the solution:

3. Would you expect your observations or your interpretations to most likely match those of your classmates? Explain.

Definitions:

Ø      Observation – a statement of fact, based on what you detect by your senses.

Ø      Interpretation – your judgment or opinion about what you have observed.

Ø      Quantitative – an observation that involves a measurement

Ø      Qualitative – a general description and does not involve a measurement.

Liz McHale

  September 20, 2006                                

      Period 8^th

       Miss Line

Chemistry

I. Title: Physical and Chemical Change

II. Objective: To investigate the criteria used to distinguish between physical and         chemical changes in matter.

III. Procedure:

            Part A: The Physical Properties of Matter.

1. Label a separate piece of paper for each of the seven substances to be examined. Place 2 pieces of magnesium ribbon, one 5 cm long and one 1 cm long, on the paper labeled “magnesium.” Using a clean spatula, transfer a pea-sized sample of the other substance to their correctly labeled papers.

2. Examine each substance with a magnifying glass. Record your observations in the Data Table 1.

3. Test the effect of a magnet on each substance by passing the magnet under the sheet of paper.

4. In separate small test tubes, test the solubility of each substance by mixing a small amount of each sample with 3mL of distilled water. ”Flick” each test tube to mix the contents.

5. Return the strip of magnesium ribbon in the test tube to its paper. Follow your teacher’s instructions for proper disposal of the other materials.  

Part B: Causing a Physical or Chemical Change.

6. Mix the iron fillings and sulfur on a clean piece of paper. Examine the mixture with a magnifying glass. Test the effect of a magnet by passing the magnet under the paper. Give this mixture to your teacher for use in Part C.

7. Mix the sodium chloride and sand on a clean piece of paper. Examine the mixture with a magnifying glass, and test the effect of a magnet.

8. Transfer the salt- sand mixture to clean 100-mL beaker. Add 30mL of tap water and stir. Record your observations. Prepare a filtrate setup as shown in Figures 2.1 and 2.2. Filter the mixture and record your observations. Pour 10 Ml of the filtrate into an evaporating dish. Prepare a setup to heat the liquid in the evaporating dish. Heat the disk gently until the filtrate has completely evaporated. Examine both the dry residue in the evaporating dish and in the wet residue on the filter paper.

9. Position a watch glass near the gas burner. Using crucible tongs, grasp one end of the5-cm strip of magnesium ribbon and hold it in the burner flame until the magnesium ignites. Quickly position the burning magnesium so that the combustion products fall on the watch glass. Compare the appearance of the product with that of the original magnesium ribbon.

10. Place the unburned 1-cm strip of magnesium and the combustion product from the watch glass into separate test tubes. Add 10 drops of 6M hydrochloric acid to each tube. Feel the bottom of each tube. Record you observations.

11. Put half of your sucrose sample into a test tube. Heat the tube gently in a burner flame and watch carefully for changes. Periodically remove the tube from the flame and check for odors by fanning the fumes toward your nose, as shown in figure 2.3.now heat the residue in the test tube more vigorously for 1-2 minutes. After cooling the tube, use a spatula to scrape some of the residue into a clean test tube. Examine the residue and test its solubility.

12. Transfer the sodium hydrogen carbonate sample to a test tube. Carefully add 5 drops of 6M hydrochloric acid. Touch the bottom of the test tube with your hand. Record your observations.

13. Follow your teacher’s instructions for proper disposal of the material.

Part C: Conservation of Mass

14. Record your observations for Part C in the Data table 2. Several samples of the iron-sulfur mixture from Part B will be combined in a clean, dry test tube. The mass of the test tube and its contents will be determined and recorded. The test tube is heated gently, then vigorously, for several minutes. After heating is complete, the mass is remeasured and recorded. Examine the reaction product. The effect of a magnet on the reaction product will be tested.

15. Your teacher will properly dispose of the materials.

IV. Data and Observations:

Data Table 1: Physical Properties Of Matter

Data Table 2: Observations of Physical and Chemical Changes

V. Questions:

1.      The fallowing is a list of changes you observe in Part B and C. Indicate whether each change was a physical change or a chemical change and give a reason for your answer.

a)      Mixing iron and sulfur. (Part B, step 6)

b)      Mixing salt, sand, and water. (Part B, step 8)

c)      Burning magnesium. (Part B, step 9)

d)      Mixing magnesium and the combustion produce with hydrochloric acid. (Part B, step10)

e)      Heating sucrose. (Part B, step 11)

f)        Mixing sodium hydrogen carbonate and hydrochloric acid. (Part B, step 12)

g)      Heating iron and sulfur. (Part C, step 14)

2.   Was mass conserved in the reaction of iron and sulfur? Explain.

3.      Except for the reaction between iron and sulfur, none of the reactions in this   experiment can be used to demonstrate the law of conservation of mass. Explain why.

4.      How do you decide whether an observed property of matter is a physical or   chemical property?

5.      What criteria are used to distinguish between a chemical change and a physical change?

6.      State in your own words the law of conservation of mass.

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well i don't hunny.
dont flatter yourself.

he's home.

RANDOM ICONS THAT I THOUGHT WERE FUNNY