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Summer 07 Chem 100 Ch 7-8.6 100 (110 possible) Pts
Name ____________________________
For Full Credit, show all of your work work
Part 1: Choose the Single closest or best answer. 5 pts each
- A process or reaction which releases heat to the surroundings is said to be
A) conservative.
B) endothermic.
C) exothermic.
D) isothermal.
E) exergonic.
- Consider the reaction shown:
C
3
H
8
+ 5 O
2
→ 3 CO
2
+ 4 H
2
O + 488 kcal
We can say that this reaction is ________ and that the sign of ΔH is ________. H is ________.
A) endothermic; positive
B) exothermic; negative
C) endothermic; negative
D) exothermic; positive
E) exothermic; neither positive nor negative
- Consider the reaction shown:
304.0 kcal + 4 PCl 3 (l) → P 4 (s) + 6 Cl 2 (g)
When 50.00 g of PCl 3 (m.w. 137.5 g/mol) react, ________ kcal will be ________.
A) 27.67; produced
B) 304.0; produced
C) 304.0; consumed
D) 27.67; consumed
E) 110.7; consumed
- A reaction that is spontaneous can be described as
A) proceeding in both the forward and reverse directions.
B) having the same rate in both the forward and reverse directions.
C) releasing heat to the surroundings.
D) proceeding without external influence once it has begun.
E) increasing in disorder.
- Which of the following processes involve an increase in entropy?
I. Mothballs vaporize in a closet.
II. Blocks are assembled into a house.
III. Crystals grow from a sugar solution.
IV. Recyclable plastics are sorted.
V. Cake mix is manufactured from five basic ingredients.
A) II, IV
B) I, II, III
C) II, III, IV
D) I, III, V
E) I, V
- A reaction is said to be ________ if the bonds formed during the reaction are stronger than the bonds
broken.
A) exothermic
B) endothermic
C) exergonic
D) endergonic
E) spontaneous
- Which statement best describes the way a catalyst works?
A) It decreases the value of ΔH is ________. H.
B) It increases the value of ΔH is ________. H.
C) It decreases the value of Eact.
D) It increases the value of Eact.
E) It increases the value of ΔH is ________. G.
- The position of the equilibrium for a system where K = 4.6 × 10
15
can be described as being favored to
________; the concentration of products is relatively ________.
A) the left; small
B) the left; large
C) the right; large
D) the right; small
E) neither direction; large
- Show using an equilibrium arrow , and change of concentration arrows and the effect of adding
nitrogen to the equilibrium system shown below. Number the arrows for clarity.
N
2
(g) + H
2
(g) ⇄ 2 NH
3
(g) + heat
- Above what temperature would you expect a reaction to become spontaneous if ΔH is ________. H = +322 kJ and
ΔH is ________. S = +531 J/K?
- What will be the new temperature be when 5580 mL of gas at 0.0 ° C is compressed to 2.5 L?
- What will be the new temperature be when a gas with a pressure or 627 torr of gas at 125.0° C is
changed to 14 atm?
