Thermodynamics - AP Chemistry
Card 1 of 1263
The second law of thermodynamics states which of the following is true regarding an isolated system?
The second law of thermodynamics states which of the following is true regarding an isolated system?
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The entropy cannot decrease in an isolated system because the energy can only be degraded. Since the system is isolated, no higher-grade energy—or any energy at all—is being introduced into the system. As a result, the entropy cannot decrease. The other answer choices relate to the other laws of thermodynamics.
The entropy cannot decrease in an isolated system because the energy can only be degraded. Since the system is isolated, no higher-grade energy—or any energy at all—is being introduced into the system. As a result, the entropy cannot decrease. The other answer choices relate to the other laws of thermodynamics.
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Which of the following statements is true of standard states?
Which of the following statements is true of standard states?
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Standard states are defined as a specific set of conditions, such as when a gas is at 
, 
concentration, and 
.
Standard enthalpy of formation, the energy required for form 1 mole of a compound from its constituent elements, occurs when elements are in their standard states.
Standard states are defined as a specific set of conditions, such as when a gas is at
Standard enthalpy of formation, the energy required for form 1 mole of a compound from its constituent elements, occurs when elements are in their standard states.
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How much heat is required to raise the temperature of 
of water from 
to 
? (Specific heat capacity of water is 
)
How much heat is required to raise the temperature of
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is positive because heat flows into the system to raise the temperature of the water.
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How much heat is required to raise the temperature of 
of water from 
to 
? Specific heat capacity of water is 
How much heat is required to raise the temperature of
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Calculating heat
How much heat is absorbed by a copper penny as it warms from 
to 
assuming the penny is pure copper with a mass of 
? 
of copper is 
.
Calculating heat
How much heat is absorbed by a copper penny as it warms from
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Use the equation that relates heat, mass, specific heat, and change in temperature:
Use the equation that relates heat, mass, specific heat, and change in temperature:
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"In a natural thermodynamic process, the sum of the entropies of the interacting systems increases." Which law of thermodynamics does this statement refer to?
"In a natural thermodynamic process, the sum of the entropies of the interacting systems increases." Which law of thermodynamics does this statement refer to?
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There are four main laws of thermodynamics, which describe how temperature, energy, and entropy behave under various circumstances. The zeroth law of thermodynamics helps to define temperature; it states that if two systems are each in thermal equilibrium with a third system, they must be in thermal equilibrium with each other. The first law of thermodynamics negates the possibility of perpetual motion; it states that when energy passes into or out of a system, the system's internal energy changes in accord with the law of conservation of energy. The second law of thermodynamics also negates the possibility of perpetual motion; it states that in a natural thermodynamic process, the sum of the entropies of the interacting systems increases. Lastly, the third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature nears absolute zero.
There are four main laws of thermodynamics, which describe how temperature, energy, and entropy behave under various circumstances. The zeroth law of thermodynamics helps to define temperature; it states that if two systems are each in thermal equilibrium with a third system, they must be in thermal equilibrium with each other. The first law of thermodynamics negates the possibility of perpetual motion; it states that when energy passes into or out of a system, the system's internal energy changes in accord with the law of conservation of energy. The second law of thermodynamics also negates the possibility of perpetual motion; it states that in a natural thermodynamic process, the sum of the entropies of the interacting systems increases. Lastly, the third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature nears absolute zero.
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Calculate the standard cell potential of the following reaction:
Zn (s) + 2 Ag1+ (aq) -> Zn2+ (aq) + 2 Ag (s)
Given:
Zn2+(aq)+ 2 e--> Zn (s) Eo = -0.76 V
Ag1+(aq)+ 1 e--> Ag (s) Eo = 0.80 V
Calculate the standard cell potential of the following reaction:
Zn (s) + 2 Ag1+ (aq) -> Zn2+ (aq) + 2 Ag (s)
Given:
Zn2+(aq)+ 2 e--> Zn (s) Eo = -0.76 V
Ag1+(aq)+ 1 e--> Ag (s) Eo = 0.80 V
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Eocell = Eo cathode - Eoanode
Eocell = 0.80 – (-0.76) = 1.56 V
Eocell = Eo cathode - Eoanode
Eocell = 0.80 – (-0.76) = 1.56 V
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Calculate the standard cell potential of the following reaction:
3 F2 (g) + 2 Au (s) -> 6 F- (aq) + 2 Au3+
Given:
F2 (g) + 2 e- -> 2 F- (aq) Eo = 2.87 V
Au3+(aq)+ 3 e--> Au (s) Eo = 1.50 V
Calculate the standard cell potential of the following reaction:
3 F2 (g) + 2 Au (s) -> 6 F- (aq) + 2 Au3+
Given:
F2 (g) + 2 e- -> 2 F- (aq) Eo = 2.87 V
Au3+(aq)+ 3 e--> Au (s) Eo = 1.50 V
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Eocell = Eo cathode - Eoanode
Eocell = 2.87 – (1.50) = 1.37 V
Eocell = Eo cathode - Eoanode
Eocell = 2.87 – (1.50) = 1.37 V
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What is the cell potential of the following cell:
Zn (s) + 2 H+(aq) -> Zn2+ (aq) + H2 (g) Eo = 0.76 V
When the \[Zn2+\] = 1.0 M; PH2 = 1 atm, and the pH in the cathode is 5.2?
What is the cell potential of the following cell:
Zn (s) + 2 H+(aq) -> Zn2+ (aq) + H2 (g) Eo = 0.76 V
When the \[Zn2+\] = 1.0 M; PH2 = 1 atm, and the pH in the cathode is 5.2?
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Calculate the standard cell potential of the following reaction:
Cd(s) + MnO2 (s) + 4 H+ (aq) + -> Cd2+ (aq) + Mn2+ (aq) + 2 H2O (l)
Given:
MnO2 (s) + 4 H+ (aq) + 2e- -> Mn2+ (aq) + 2 H2O (l) Eo = 1.23 V
Cd2+ (aq) + 2 e- -> Cd (s) Eo = -0.40 V
Calculate the standard cell potential of the following reaction:
Cd(s) + MnO2 (s) + 4 H+ (aq) + -> Cd2+ (aq) + Mn2+ (aq) + 2 H2O (l)
Given:
MnO2 (s) + 4 H+ (aq) + 2e- -> Mn2+ (aq) + 2 H2O (l) Eo = 1.23 V
Cd2+ (aq) + 2 e- -> Cd (s) Eo = -0.40 V
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Eocell = Eo cathode - Eoanode
Eocell = 1.23 – (-0.40) = 1.63 V
Eocell = Eo cathode - Eoanode
Eocell = 1.23 – (-0.40) = 1.63 V
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How much heat does it take to heat 100g ice at 0C to boiling point?
Cice= 2.1 J/goC
Cwater= 4.2 J/goC
ΔHvap= 2260 J/g
ΔHfus=334 J/g
How much heat does it take to heat 100g ice at 0C to boiling point?
Cice= 2.1 J/goC
Cwater= 4.2 J/goC
ΔHvap= 2260 J/g
ΔHfus=334 J/g
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You need heat for the phase change, using the enthalpy of fusion (100g*334 J/g = 33400 J). Add to this the heat to get to boiling point using the specific heat of water (100g*100C*4.2 J/goC = 42000 J). Totalling 75400 J (75.4 kJ)
You need heat for the phase change, using the enthalpy of fusion (100g*334 J/g = 33400 J). Add to this the heat to get to boiling point using the specific heat of water (100g*100C*4.2 J/goC = 42000 J). Totalling 75400 J (75.4 kJ)
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A 50g sample of a metal was heated to 
then quickly transferred to an insulated container containing 50g of 
at 
. The final temperature of the 
was 
.
Which of the following can be concluded?
A 50g sample of a metal was heated to
Which of the following can be concluded?
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When the heated metal is placed in the container of the cooler water there will be a transfer of thermal energy from the metal to the water. This transfer will occur towards an equilibrium of thermal energy in the water and in the metal. Thus we can conclude that the amount of thermal energy lost by the metal will equal the amount of thermal energy gained by the water. However we notice that the water increases by only 5oC and the metal decreases by 65oC. This is becasue of the difference of the specific heats of these substances. The specific heat capacity of a substance is the heat required to increase the temperature of 1g of a substance by 1oC. The metal can be conluded to have a smaller specific heat than the water because the same amount of energy transfer led to a much larger change in termperature for the metal as compared to the water.
When the heated metal is placed in the container of the cooler water there will be a transfer of thermal energy from the metal to the water. This transfer will occur towards an equilibrium of thermal energy in the water and in the metal. Thus we can conclude that the amount of thermal energy lost by the metal will equal the amount of thermal energy gained by the water. However we notice that the water increases by only 5oC and the metal decreases by 65oC. This is becasue of the difference of the specific heats of these substances. The specific heat capacity of a substance is the heat required to increase the temperature of 1g of a substance by 1oC. The metal can be conluded to have a smaller specific heat than the water because the same amount of energy transfer led to a much larger change in termperature for the metal as compared to the water.
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Which of the following is the correct molar specific heat of water used when making calculations involving a calorimeter?
Which of the following is the correct molar specific heat of water used when making calculations involving a calorimeter?
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4.184 J/gK is the cited value for the specific heat of water and should be memorized. This is used during calorimeter calculations, specifically when using the equation q= mc delta(T).
4.184 J/gK is the cited value for the specific heat of water and should be memorized. This is used during calorimeter calculations, specifically when using the equation q= mc delta(T).
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In which instance would a bomb calorimeter be more useful than a coffee-cup calorimeter?
In which instance would a bomb calorimeter be more useful than a coffee-cup calorimeter?
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Bomb calorimeters are most useful when dealing with a gas, because they can operate well at high pressures. Coffee-cup calorimeters are not useful when water begins to boil, producing vapor.
Bomb calorimeters are most useful when dealing with a gas, because they can operate well at high pressures. Coffee-cup calorimeters are not useful when water begins to boil, producing vapor.
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The specific heat capacity of an unknown liquid is 
. The density of the liquid is 
If a chemist applies 243 J of heat to 300 mL of this liquid starting at 
, what is the final temperature?
The specific heat capacity of an unknown liquid is
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First we will determine the mass of the liquid:
Now we will examine the relationship between heat and specific heat capacity:
Where 
is heat in Joules, 
is the specific heat capacity, 
is the mass and 
is the change in temperature. We can rearrange this
If we begin at 
, we will end at 
First we will determine the mass of the liquid:
Now we will examine the relationship between heat and specific heat capacity:
Where
If we begin at
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The following is a list of specific heat capacities for a few metals.
A 50g sample of an unknown metal is heated with 800 joules. If the temperature of the metal increases by 41.6oC, what is the identity of the unknown metal?
The following is a list of specific heat capacities for a few metals.
A 50g sample of an unknown metal is heated with 800 joules. If the temperature of the metal increases by 41.6oC, what is the identity of the unknown metal?
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We need to find the specific heat of the unknown sample of metal in order to locate it on the list. We can do this by using the equation that allows us to determine the specific heat capacity of an element.
Since we know the change in temperature, we can simply plug in the values and solve for the value of 
.
Going back to the list, we see that this is the specific heat capacity for copper, so we confirm that the unknown metal is copper.
We need to find the specific heat of the unknown sample of metal in order to locate it on the list. We can do this by using the equation that allows us to determine the specific heat capacity of an element.
Since we know the change in temperature, we can simply plug in the values and solve for the value of
Going back to the list, we see that this is the specific heat capacity for copper, so we confirm that the unknown metal is copper.
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A 20g sample of iron at a temperature of 
is placed into a container of water. There are 300 milliliters of water in the container at a temperature of 
.
What is the final temperature of the water?
A 20g sample of iron at a temperature of
What is the final temperature of the water?
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There are two things to note before solving for the final temperature.
1. The density of water allows us to say that 300 milliliters of water is the same thing as 300 grams of water.
2. Since the heat from the iron is being transferred to the water, we can say that the heat transfer is equal between both compounds. Since the heat is conserved in the system, we can set the two equations equal to one another.
Notice how the change in temperature for iron has been flipped in order to avoid a negative number.
Because water has a much higher heat capacity compared to iron, the temperature of the water is not changed significantly.
There are two things to note before solving for the final temperature.
1. The density of water allows us to say that 300 milliliters of water is the same thing as 300 grams of water.
2. Since the heat from the iron is being transferred to the water, we can say that the heat transfer is equal between both compounds. Since the heat is conserved in the system, we can set the two equations equal to one another.
Notice how the change in temperature for iron has been flipped in order to avoid a negative number.
Because water has a much higher heat capacity compared to iron, the temperature of the water is not changed significantly.
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How much energy is needed to raise the temperature of five grams of ice from 
to 
?
How much energy is needed to raise the temperature of five grams of ice from
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This question involves the total energy needed for three different processes: the temperature raise from 
to 
, the melting of the ice, and the temperature raise from 
to 
. For the first and third transitions we will use the equation 
. For the melting of ice, we will use the equation 
.
1. 
2. 
3. 
Finally, we will need to sum the energy required for each step to find the total energy.
This question involves the total energy needed for three different processes: the temperature raise from
1.
2.
3.
Finally, we will need to sum the energy required for each step to find the total energy.
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You want to prepare a cup of tea. To do so, you pour 
of tap water at 
in a cup that does not absorb microwave radiation and heat it in a microwave oven at 
of power. If you assume a density of 
for the water and know that its specific heat capacity is 
, what time do you need to set in the microwave oven to heat the water to 
?
You want to prepare a cup of tea. To do so, you pour
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Since the density of water is 
, the mass of 
is 
. Plug in known values to the equation and solve.
Use the formula below to find the time needed to heat up the sample of water in the microwave:
Our answer must contain three significant figures.
Since the density of water is
Use the formula below to find the time needed to heat up the sample of water in the microwave:
Our answer must contain three significant figures.
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Calculate the standard cell potential of the following reaction:
Zn (s) + Cu2+ (aq) -> Zn2+ (aq) + Cu (s)
Given:
Zn2+(aq)+ 2 e--> Zn (s) Eo = -0.76 V
Cu2+(aq)+ 2 e--> Cu (s) Eo = 0.34 V
Calculate the standard cell potential of the following reaction:
Zn (s) + Cu2+ (aq) -> Zn2+ (aq) + Cu (s)
Given:
Zn2+(aq)+ 2 e--> Zn (s) Eo = -0.76 V
Cu2+(aq)+ 2 e--> Cu (s) Eo = 0.34 V
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Eocell = Eo cathode - Eoanode
Eocell = 0.34 – (-0.76) = 1.10 V
Eocell = Eo cathode - Eoanode
Eocell = 0.34 – (-0.76) = 1.10 V
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