7980 - 1 - Page 1 Name: ____________________________________________ 1)

7980 - 1 - Page 1
Name: ____________________________________________
1)
As a 1-gram sample of H2O(g) changes to H2O(l) at 100DC, the potential energy of the molecules
A) decreases
2)
B) remains the same
C) increases
The graph below represents the uniform heating of a solid, starting below its melting point.
What portion of the graph shows the solid and liquid phases of the substance existing in equilibrium?
A) BC
3)
B) DE
C) CD
D) AB
The graph below represents the uniform cooling of a sample of a substance, starting with the substance as a gas above its
boiling point.
What segment of the curve represents a time when both the liquid and the solid phases are present?
A) DE
4)
C) BC
D) CD
C) liquid to a gas
D) solid to a gas
Which change of phase is exothermic?
A) gas to a liquid
5)
B) EF
B) solid to a liquid
Which graph best represents a change of phase from a gas to a solid?
A)
C)
B)
D)
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6)
The graph below represents the uniform cooling of water at 1 atmosphere, starting with water as a gas above its boiling point.
What segments of the cooling curve represent the fixed points on a thermometer?
A) CD and EF
7)
C) BC and DE
D) AB and CD
C) gas to a solid
D) solid to a liquid
Which change of phase is exothermic?
A) liquid to a gas
8)
B) AB and EF
B) solid to a gas
The graph below represents the relationship between temperature and time as heat was added uniformly to a substance, starting
as a solid below its melting point.
During the BC portion of the curve, the average kinetic energy of the molecules of the substance
A) remains the same and the potential energy increases
B) increases and the potential energy increases
9)
C) remains the same and the potential energy decreases
D) decreases and the potential energy increases
A student collected data in an experiment in which the uniform cooling of a water sample was observed from 50DC to -32DC.
Which graph most likely represents the results obtained by the student?
A)
C)
B)
D)
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Questions 10 and 11 refer to the following:
The diagram below represents the uniform heating of a water sample at standard pressure, starting at a temperature below 0DC.
10)
The number of joules required to vaporize the entire sample of water at its boiling point is represented by the interval between
A) E and F
11)
C) D and E
D) A and B
If 5 grams of water undergoes a temperature change from C to D, the total energy absorbed is
A) 100 joules
12)
B) C and D
B) 418 joules
C) 2,090 joules
D) 333.6 joules
In the graph below, a substance is cooled from a liquid to a solid at a rate of 50 joules per minute.
If the rate were changed to 100 joules per minute, which sequence of points would represent the new cooling curve?
A) AXYZ
13)
C) AWCD
D) AXCD
C) gas to liquid
D) liquid to solid
Which phase change is endothermic?
A) gas to solid
14)
B) AWXZ
B) liquid to gas
The diagram below represents the uniform heating of a substance that is a solid at t0.
What is the freezing point of the substance?
A) 12DC
B) 100DC
C) 60DC
D) 1DC
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15)
The graph below represents the uniform cooling of a substance starting as a gas at 160DC.
At which temperature does a phase change occur for this substance?
A) 140DC
16)
B) 0DC
C) 40DC
D) 80DC
The graph below represents the relationship between the temperature and time for a substance that was heated uniformly starting
at t 0. The substance was in the solid phase at t 0.
During what time interval does the heat absorbed by the substance represent the heat of fusion of the substance?
A) t 3 to t 4
17)
B) t 1 to t 2
C) t 0 to t 1
D) t 2 to t 3
The graph below represents changes of state for an unknown substance.
What is the boiling temperature of the substance?
A) 40DC
B) 70DC
C) 0DC
D) 20DC
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18)
In the heating curve shown below, heat is applied to a solid substance at a constant rate.
What accounts for the fact that segment CD is longer than segment AB?
A)
B)
C)
D)
Average kinetic energy increases at a greater rate during boiling than during melting.
Potential energy is being released during boiling.
The heat of vaporization is greater than the heat of fusion.
Boiling occurs at a higher temperature than melting.
Questions 19 and 20 refer to the following:
The graph below shows the relationship between temperature and time as heat is added to one mole of a substance at a rate of
100 joules per minute. The substance is in the solid phase at 0 minutes.
19)
From the time that the solid begins to melt, the minimum number of joules required to completely melt the one mole sample is
A) 200
20)
B) 100
C) 600
D) 400
C) 80DC
D) 10DC
At what temperature does the substance begin to boil?
A) 110DC
B) 40DC
Questions 21 and 22 refer to the following:
The graph below represents uniform cooling of a sample of a pure substance, starting as a gas.
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21)
The boiling point of the substance is
A) 120DC
22)
B) C and D
25)
D) 60DC
C) E and F
D) D and E
As a 1-gram sample of H2O(l) changes to H2O(g) at 100DC, the potential energy of the molecules
A) decreases
24)
C) 180DC
Solid and liquid phases can exist in equilibrium between points
A) B and C
23)
B) 10DC
B) remains the same
C) increases
Which change results in a release of energy?
A) the melting of H2O(s)
C) the condensation of H2O(g)
B) the evaporation of H2O(l)
D) the boiling of H2O(l)
The graph below represents the relationship between temperature and time as heat is added uniformly to a substance, starting
when the substance is a solid below its melting point.
What portions of the graph represent times when heat is absorbed and potential energy increases while kinetic energy remains
constant?
A) A and B
26)
B) C and D
C) B and D
D) A and C
The graph below represents the cooling curve of a substance starting at a temperature below the boiling point of the substance.
During what interval was the substance completely in the solid phase?
A) A to C
B) A to B
C) C to D
D) B to C