s8pe-309cr-ca
12/6/05
4:24 PM
MAZER
Page 298
Thinking Critically
0 Min.
68˚C
1
Using Math Skills in Science
2
5 Min.
74˚C
Answer the following ten questions based on
the equations below.
Equation 1—HgO
Hg + O2
Equation 2—Al + O2
Al2O3
Equation 3—S8 + O2
SO3
25. Copy and balance equation 1. (8.5.b)
10 Min.
80˚C
3
4
15 Min.
90˚C
26. What coefficients, if any, did you add to
equation 1 to balance it? (8.5.b)
27. How many Hg atoms take part in the reaction
shown by equation 1 when it is balanced?
(8.5.b)
28. Copy and balance equation 2. (8.5.b)
The series of illustrations above shows a
chemical reaction at five-minute intervals.
Use the information in the illustrations to
answer the following six questions.
19. OBSERVE What happened to the temperature
of the substance in the beaker from the beginning to the end of each five-minute interval?
(8.5.c)
29. What coefficients, if any, did you add to
equation 2 to balance it? (8.5.b)
30. How many O atoms take part in the reaction
shown in equation 2 when it is balanced? (8.5.b)
31. Copy and balance equation 3. (8.5.b)
32. What coefficients, if any, did you add to
equation 3 to balance it? (8.5.b)
20. ANALYZE Does the reaction appear to continue
in step 4? What evidence tells you?
33. How many S atoms take part in the reaction
shown in equation 3 when it is balanced? (8.5.b)
21. CLASSIFY Is this an endothermic or exothermic
reaction? Explain. (8.5.c)
34. How many O atoms take part in the reaction
shown in equation 3 when it is balanced? (8.5.b)
22. INFER Suppose the metal cube placed in the
beaker in step 3 is a catalyst. What effect did
the metal have on the reaction? Why? (8.5.a)
23. PREDICT If the metal cube is a catalyst, how
much of the metal cube will be left in the
beaker when the reaction is completed?
Explain. (8.5.a)
24. SYNTHESIZE Assume that the reaction shown
is a decomposition reaction. Describe what
happens to the reactants. (8.5.a)
35. DRAW CONCLUSIONS Describe three chemical
reactions you see each day. How do you know
they are chemical reactions?
36. ANALYZE Look back at the photograph and
question on pages 268 and 269. Answer the
question in terms of the chapter’s Big Idea.
Check your schedule for your unit project. How
are you doing? Be sure that you have placed data
or notes from your research in your project folder.
298 Unit 3: Chemical Interactions
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