Solutions to Exam Review #3

  1. C (raising temperature does not affect activation energy. It only increases the percent of molecules that have more than enough energy to react.
  2. D (Catalysts lower the activation energy.)
  3. C
  4. D
  5. B
  6. C (This is because twice as much Mg is exposed to the HCl)
  7. D
  8. D ( Itís the only answer > 60s. Lowering the temperature increases the time it will take to react.)
  9. Answer should be 2,3,1. #2 is the slowest because it involves breaking and reforming covalent bonds, exclusively. #1 is the fastest because it is a precipitation reaction.
  10. B (Pressure is not a factor if no gases are involved in the reaction.)
  11. D
  12. -1.8 X10-5 (mol/L)/s
  13. a. Lowering temperature slows down the number of effective collisions between the oxygen and the wineís vulnerable molecules. This lowers the rate of oxidation.
  1. Recorking prevents any more oxygen from entering the bottle and thus slows down the oxidation of wine.

††††† 14.

Time (s)

Number of Moles

Unreacted AB

Number of Moles

Reacted AB = 2.8-moles of

Unreacted AB

Number of Moles

A produced = Number of Moles

Reacted AB(since ratio is 2:2)

0

2.8

0

0

3

1.2

1.6

1.6

5

0.8

2.0

2.0

8

0.6

2.2

2.2

 

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Created:April/6/1996; Updated:Dec/1/2009