1. Experiment 4 Chemical Reactions
Demonstration for part A, selected reactions for parts B and C
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2. Purpose of This Experiment
Make accurate observations for a chemical reaction
Figure out what the products of the chemical reaction are
Write balanced chemical equations for the chemical reactions
Work in groups of 2
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3. Terminology for Observations
Gas Formation – bubbles are formed, solution fizzes Solid Formation, Precipitate Formation– solution becomes cloudy, solid material forms and may settle to the bottom of the test tube (color?) Color Change – solution may change from one color to another (indicate initial and final colors) Temperature Change – solution may become warmer or cooler, indicate direction of change
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4. Determining Product
Use observations and Table 4.1 to determine the product of the chemical reaction
The remaining elements (ions) are probably spectators
The instructions for this experiment also give indications for the products formed (especially the bottom of page 46)
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5. Writing Balanced Chemical Equations
Use the molecular equation format (everything is written as neutral compounds)
Remember to use (s), (l), (g), (aq) as needed for all substances in the equations
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6. Part A PowerPoint demonstration (students do not do this reaction)
Make your observations for your report sheet while the PowerPoint is shown
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7. Parts B and C Do selected reactions only, at your lab bench
Do not return unused reagents to their original bottles. Pour unused reagents into the waste bottles in hoods.
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8. Part B
Observations given: Report line # 12: A brown gas forms and the Cu dissolves Report line # 13: Yes, brown Report line # 15: blue color, student still needs to write formula of substance Report line # 20: KMnO4 dissolves and a gas forms Report line # 21: Pale yellow-green gas forms, pungent odor to gas
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9. Part C
Observations given: Report line # 27: gas produced Report line # 30: gas produced Report line # 33: white precipitate forms Report line # 36: yellow precipitate forms Report line # 26: typing error, should be Na2CO3
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