Endergonic and Exergonic Reactions - MCAT Chemical and Physical Foundations of Biological Systems
Card 1 of 42
For “Reaction A,” 
is +300kJ and 
is -98J. The reaction will be spontaneous under which of the following conditions?
For “Reaction A,”
Tap to reveal answer
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
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The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
Tap to reveal answer
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
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The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
In which of the scenarios will the reaction be spontaneous?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
In which of the scenarios will the reaction be spontaneous?
Tap to reveal answer
All of the following scenarios would lead to spontaneous reaction, since each scenario would result in a negative Gibbs free energy (-ΔG).
Negative enthalpy, positive entropy:
Positive enthalpy and entropy with high temperature:
Negative enthalpy and entropy with low temperature:
All of the following scenarios would lead to spontaneous reaction, since each scenario would result in a negative Gibbs free energy (-ΔG).
Negative enthalpy, positive entropy:
Positive enthalpy and entropy with high temperature:
Negative enthalpy and entropy with low temperature:
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Which of the following scenarios describes a reaction in equilibrium?
Which of the following scenarios describes a reaction in equilibrium?
Tap to reveal answer
According to the Gibbs free energy equation, a system is at equilibrium when 
is equal to 0.
Since 
, a system is in equilibrium when 
. A negative Gibbs free energy means that the reaction will be spontaneous. At equilibrium, the forward reaction rate equals the reverse reaction rate, though the net rate is zero.
According to the Gibbs free energy equation, a system is at equilibrium when
Since
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Boiling point is the temperature a liquid needs to achieve in order to begin its transformation into a gaseous state. Campers and hikers who prepare food during their trips have to account for differences in atmospheric pressure as they ascend in elevation. During the ascent, the decrease in atmospheric pressure changes the temperature at which water boils.
Further complicating the matter is the observation that addition of a solute to a pure liquid also changes the boiling point. Raoult’s Law can be used to understand the changes in boiling point if a non-volatile solute is present, as expressed here.
In this law, 
is the mole fraction of the solvent, 
is the vapor pressure of the pure solvent, and 
is the vapor pressure of the solution. When this vapor pressure is equal to the local atmospheric pressure, the solution boils.
A scientist is studying solution chemistry to better understand vapor pressure. He finds that, for one solution he creates, the beaker is cool to the touch after the solute is fully dissolved. Which of the following is true of this solution? (Note: The beaker, solute, and solvent are the system, the remainder of the universe is the surroundings)
Boiling point is the temperature a liquid needs to achieve in order to begin its transformation into a gaseous state. Campers and hikers who prepare food during their trips have to account for differences in atmospheric pressure as they ascend in elevation. During the ascent, the decrease in atmospheric pressure changes the temperature at which water boils.
Further complicating the matter is the observation that addition of a solute to a pure liquid also changes the boiling point. Raoult’s Law can be used to understand the changes in boiling point if a non-volatile solute is present, as expressed here.
In this law,
A scientist is studying solution chemistry to better understand vapor pressure. He finds that, for one solution he creates, the beaker is cool to the touch after the solute is fully dissolved. Which of the following is true of this solution? (Note: The beaker, solute, and solvent are the system, the remainder of the universe is the surroundings)
Tap to reveal answer
The act of dissolving a solute in a solvent is a local increase in entropy, converting a single molecule to multiple ions. The absorption of heat from the surroundings (cool beaker) indicates that this is an endothermic dissolution. We can look at the equation for Gibbs free energy to evaluate the possible answers.
In order to be spontaneous, the reaction must have a negative Gibbs free energy. To accomplish this, a reaction may have a negative enthalpy (exothermic) and positive entropy, however we know that our reaction has a positive enthalpy (endothermic) and positive entropy. A reaction will be spontaneous if it has a positive 
and a positive 
only when temperature is high.
The act of dissolving a solute in a solvent is a local increase in entropy, converting a single molecule to multiple ions. The absorption of heat from the surroundings (cool beaker) indicates that this is an endothermic dissolution. We can look at the equation for Gibbs free energy to evaluate the possible answers.
In order to be spontaneous, the reaction must have a negative Gibbs free energy. To accomplish this, a reaction may have a negative enthalpy (exothermic) and positive entropy, however we know that our reaction has a positive enthalpy (endothermic) and positive entropy. A reaction will be spontaneous if it has a positive
← Didn't Know|Knew It →
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
Assume that the forward reaction in the passage is exothermic, and has a 
value of 
. Which of the following is true?
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
Assume that the forward reaction in the passage is exothermic, and has a
Tap to reveal answer
The question specifies that this reaction is exothermic, and that it has a positive local increase in entropy as it progresses. This means that the change in enthaply is negative and the change in entropy is positive.
For a reaction to be spontaneous, Gibbs free energy must be negative.
If enthalpy is negative and entropy is positive, the temperature is irrelevant and Gibbs free energy will always be negative.
The reaction is spontaneous at any temperature.
The question specifies that this reaction is exothermic, and that it has a positive local increase in entropy as it progresses. This means that the change in enthaply is negative and the change in entropy is positive.
For a reaction to be spontaneous, Gibbs free energy must be negative.
If enthalpy is negative and entropy is positive, the temperature is irrelevant and Gibbs free energy will always be negative.
The reaction is spontaneous at any temperature.
← Didn't Know|Knew It →
For “Reaction A,” is +300kJ and is -98J. The reaction will be spontaneous under which of the following conditions?
For “Reaction A,”
Tap to reveal answer
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
← Didn't Know|Knew It →
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
Tap to reveal answer
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
← Didn't Know|Knew It →
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
In which of the scenarios will the reaction be spontaneous?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
In which of the scenarios will the reaction be spontaneous?
Tap to reveal answer
All of the following scenarios would lead to spontaneous reaction, since each scenario would result in a negative Gibbs free energy (-ΔG).
Negative enthalpy, positive entropy:
Positive enthalpy and entropy with high temperature:
Negative enthalpy and entropy with low temperature:
All of the following scenarios would lead to spontaneous reaction, since each scenario would result in a negative Gibbs free energy (-ΔG).
Negative enthalpy, positive entropy:
Positive enthalpy and entropy with high temperature:
Negative enthalpy and entropy with low temperature:
← Didn't Know|Knew It →
Which of the following scenarios describes a reaction in equilibrium?
Which of the following scenarios describes a reaction in equilibrium?
Tap to reveal answer
According to the Gibbs free energy equation, a system is at equilibrium when is equal to 0.
Since , a system is in equilibrium when . A negative Gibbs free energy means that the reaction will be spontaneous. At equilibrium, the forward reaction rate equals the reverse reaction rate, though the net rate is zero.
According to the Gibbs free energy equation, a system is at equilibrium when
Since
← Didn't Know|Knew It →
Boiling point is the temperature a liquid needs to achieve in order to begin its transformation into a gaseous state. Campers and hikers who prepare food during their trips have to account for differences in atmospheric pressure as they ascend in elevation. During the ascent, the decrease in atmospheric pressure changes the temperature at which water boils.
Further complicating the matter is the observation that addition of a solute to a pure liquid also changes the boiling point. Raoult’s Law can be used to understand the changes in boiling point if a non-volatile solute is present, as expressed here.
In this law, is the mole fraction of the solvent, is the vapor pressure of the pure solvent, and is the vapor pressure of the solution. When this vapor pressure is equal to the local atmospheric pressure, the solution boils.
A scientist is studying solution chemistry to better understand vapor pressure. He finds that, for one solution he creates, the beaker is cool to the touch after the solute is fully dissolved. Which of the following is true of this solution? (Note: The beaker, solute, and solvent are the system, the remainder of the universe is the surroundings)
Boiling point is the temperature a liquid needs to achieve in order to begin its transformation into a gaseous state. Campers and hikers who prepare food during their trips have to account for differences in atmospheric pressure as they ascend in elevation. During the ascent, the decrease in atmospheric pressure changes the temperature at which water boils.
Further complicating the matter is the observation that addition of a solute to a pure liquid also changes the boiling point. Raoult’s Law can be used to understand the changes in boiling point if a non-volatile solute is present, as expressed here.
In this law,
A scientist is studying solution chemistry to better understand vapor pressure. He finds that, for one solution he creates, the beaker is cool to the touch after the solute is fully dissolved. Which of the following is true of this solution? (Note: The beaker, solute, and solvent are the system, the remainder of the universe is the surroundings)
Tap to reveal answer
The act of dissolving a solute in a solvent is a local increase in entropy, converting a single molecule to multiple ions. The absorption of heat from the surroundings (cool beaker) indicates that this is an endothermic dissolution. We can look at the equation for Gibbs free energy to evaluate the possible answers.
In order to be spontaneous, the reaction must have a negative Gibbs free energy. To accomplish this, a reaction may have a negative enthalpy (exothermic) and positive entropy, however we know that our reaction has a positive enthalpy (endothermic) and positive entropy. A reaction will be spontaneous if it has a positive and a positive only when temperature is high.
The act of dissolving a solute in a solvent is a local increase in entropy, converting a single molecule to multiple ions. The absorption of heat from the surroundings (cool beaker) indicates that this is an endothermic dissolution. We can look at the equation for Gibbs free energy to evaluate the possible answers.
In order to be spontaneous, the reaction must have a negative Gibbs free energy. To accomplish this, a reaction may have a negative enthalpy (exothermic) and positive entropy, however we know that our reaction has a positive enthalpy (endothermic) and positive entropy. A reaction will be spontaneous if it has a positive
← Didn't Know|Knew It →
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
Assume that the forward reaction in the passage is exothermic, and has a value of . Which of the following is true?
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
Assume that the forward reaction in the passage is exothermic, and has a
Tap to reveal answer
The question specifies that this reaction is exothermic, and that it has a positive local increase in entropy as it progresses. This means that the change in enthaply is negative and the change in entropy is positive.
For a reaction to be spontaneous, Gibbs free energy must be negative.
If enthalpy is negative and entropy is positive, the temperature is irrelevant and Gibbs free energy will always be negative.
The reaction is spontaneous at any temperature.
The question specifies that this reaction is exothermic, and that it has a positive local increase in entropy as it progresses. This means that the change in enthaply is negative and the change in entropy is positive.
For a reaction to be spontaneous, Gibbs free energy must be negative.
If enthalpy is negative and entropy is positive, the temperature is irrelevant and Gibbs free energy will always be negative.
The reaction is spontaneous at any temperature.
← Didn't Know|Knew It →
For “Reaction A,” is +300kJ and is -98J. The reaction will be spontaneous under which of the following conditions?
For “Reaction A,”
Tap to reveal answer
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
← Didn't Know|Knew It →
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
Tap to reveal answer
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
← Didn't Know|Knew It →
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
In which of the scenarios will the reaction be spontaneous?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
In which of the scenarios will the reaction be spontaneous?
Tap to reveal answer
All of the following scenarios would lead to spontaneous reaction, since each scenario would result in a negative Gibbs free energy (-ΔG).
Negative enthalpy, positive entropy:
Positive enthalpy and entropy with high temperature:
Negative enthalpy and entropy with low temperature:
All of the following scenarios would lead to spontaneous reaction, since each scenario would result in a negative Gibbs free energy (-ΔG).
Negative enthalpy, positive entropy:
Positive enthalpy and entropy with high temperature:
Negative enthalpy and entropy with low temperature:
← Didn't Know|Knew It →
Which of the following scenarios describes a reaction in equilibrium?
Which of the following scenarios describes a reaction in equilibrium?
Tap to reveal answer
According to the Gibbs free energy equation, a system is at equilibrium when is equal to 0.
Since , a system is in equilibrium when . A negative Gibbs free energy means that the reaction will be spontaneous. At equilibrium, the forward reaction rate equals the reverse reaction rate, though the net rate is zero.
According to the Gibbs free energy equation, a system is at equilibrium when
Since
← Didn't Know|Knew It →
Boiling point is the temperature a liquid needs to achieve in order to begin its transformation into a gaseous state. Campers and hikers who prepare food during their trips have to account for differences in atmospheric pressure as they ascend in elevation. During the ascent, the decrease in atmospheric pressure changes the temperature at which water boils.
Further complicating the matter is the observation that addition of a solute to a pure liquid also changes the boiling point. Raoult’s Law can be used to understand the changes in boiling point if a non-volatile solute is present, as expressed here.
In this law, is the mole fraction of the solvent, is the vapor pressure of the pure solvent, and is the vapor pressure of the solution. When this vapor pressure is equal to the local atmospheric pressure, the solution boils.
A scientist is studying solution chemistry to better understand vapor pressure. He finds that, for one solution he creates, the beaker is cool to the touch after the solute is fully dissolved. Which of the following is true of this solution? (Note: The beaker, solute, and solvent are the system, the remainder of the universe is the surroundings)
Boiling point is the temperature a liquid needs to achieve in order to begin its transformation into a gaseous state. Campers and hikers who prepare food during their trips have to account for differences in atmospheric pressure as they ascend in elevation. During the ascent, the decrease in atmospheric pressure changes the temperature at which water boils.
Further complicating the matter is the observation that addition of a solute to a pure liquid also changes the boiling point. Raoult’s Law can be used to understand the changes in boiling point if a non-volatile solute is present, as expressed here.
In this law,
A scientist is studying solution chemistry to better understand vapor pressure. He finds that, for one solution he creates, the beaker is cool to the touch after the solute is fully dissolved. Which of the following is true of this solution? (Note: The beaker, solute, and solvent are the system, the remainder of the universe is the surroundings)
Tap to reveal answer
The act of dissolving a solute in a solvent is a local increase in entropy, converting a single molecule to multiple ions. The absorption of heat from the surroundings (cool beaker) indicates that this is an endothermic dissolution. We can look at the equation for Gibbs free energy to evaluate the possible answers.
In order to be spontaneous, the reaction must have a negative Gibbs free energy. To accomplish this, a reaction may have a negative enthalpy (exothermic) and positive entropy, however we know that our reaction has a positive enthalpy (endothermic) and positive entropy. A reaction will be spontaneous if it has a positive and a positive only when temperature is high.
The act of dissolving a solute in a solvent is a local increase in entropy, converting a single molecule to multiple ions. The absorption of heat from the surroundings (cool beaker) indicates that this is an endothermic dissolution. We can look at the equation for Gibbs free energy to evaluate the possible answers.
In order to be spontaneous, the reaction must have a negative Gibbs free energy. To accomplish this, a reaction may have a negative enthalpy (exothermic) and positive entropy, however we know that our reaction has a positive enthalpy (endothermic) and positive entropy. A reaction will be spontaneous if it has a positive
← Didn't Know|Knew It →
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
Assume that the forward reaction in the passage is exothermic, and has a value of . Which of the following is true?
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
Assume that the forward reaction in the passage is exothermic, and has a
Tap to reveal answer
The question specifies that this reaction is exothermic, and that it has a positive local increase in entropy as it progresses. This means that the change in enthaply is negative and the change in entropy is positive.
For a reaction to be spontaneous, Gibbs free energy must be negative.
If enthalpy is negative and entropy is positive, the temperature is irrelevant and Gibbs free energy will always be negative.
The reaction is spontaneous at any temperature.
The question specifies that this reaction is exothermic, and that it has a positive local increase in entropy as it progresses. This means that the change in enthaply is negative and the change in entropy is positive.
For a reaction to be spontaneous, Gibbs free energy must be negative.
If enthalpy is negative and entropy is positive, the temperature is irrelevant and Gibbs free energy will always be negative.
The reaction is spontaneous at any temperature.
← Didn't Know|Knew It →
For “Reaction A,” is +300kJ and is -98J. The reaction will be spontaneous under which of the following conditions?
For “Reaction A,”
Tap to reveal answer
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
The spontaneity of a reaction is determined by the equation for Gibbs free energy.
Here, H is a positive number and S is negative, meaning that G will always be a positive value. T will be given in Kelvin, and cannot be negative. Reactions with positive Gibbs free energy values are never spontaneous.
← Didn't Know|Knew It →
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
The equation for the change in Gibbs free energy is given below.
ΔH = change in enthalpy
ΔS = change in entropy
Which of the following scenarios guarantees a nonspontaneous reaction?
Tap to reveal answer
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
A positive value for ΔG (Gibbs free energy) will guarantee a nonspontaneous reaction. When ΔH (enthalpy) is postive and ΔS (entropy) is negative, the change in Gibbs free energy must be positive and, therefore, nonspontaneous.
Because T (temperature) will always have a positive value, a negative entropy and positive enthalpy will always result in a positive Gibbs free energy.
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