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Questions and Answers
Under what condition can the entropy of an isolated system never occur?
Under what condition can the entropy of an isolated system never occur?
- Remain constant
- Fluctuate
- Decrease (correct)
- Increase
Which statement is true of a reversible chemical reaction that has reached equilibrium?
Which statement is true of a reversible chemical reaction that has reached equilibrium?
- The reaction proceeds alternately in the forward and reverse directions.
- The reaction halts, with no further change in concentrations.
- The reaction proceeds unidirectionally until completion.
- The rates of the forward and reverse reactions are equal. (correct)
Which transformation is most likely to result in a decrease in entropy?
Which transformation is most likely to result in a decrease in entropy?
- $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$ (correct)
- $H_2O(l) \rightarrow H_2O(g)$
- $2H_2O_2(aq) \rightarrow 2H_2O(l) + O_2(g)$
- $NaCl(s) \rightarrow Na^+(aq) + Cl^-(aq)$
Given the reactions (a) $O_2(g) + N_2(g) \rightarrow N_2O(g)$ and (b) $N_2O(g) \rightarrow O_2(g) + N_2(g)$, which reaction is associated with a decrease in entropy?
Given the reactions (a) $O_2(g) + N_2(g) \rightarrow N_2O(g)$ and (b) $N_2O(g) \rightarrow O_2(g) + N_2(g)$, which reaction is associated with a decrease in entropy?
Which phase change is associated with an increase in the entropy of the substance?
Which phase change is associated with an increase in the entropy of the substance?
How does entropy change in an isolated system as it approaches a state of equilibrium?
How does entropy change in an isolated system as it approaches a state of equilibrium?
Which of the following best describes the second law of thermodynamics?
Which of the following best describes the second law of thermodynamics?
Which of the following is a direct application of the entropy principle?
Which of the following is a direct application of the entropy principle?
Under what enthalpy and entropy conditions will a process never be spontaneous?
Under what enthalpy and entropy conditions will a process never be spontaneous?
Under what conditions is a reaction only spontaneous at high temperatures?
Under what conditions is a reaction only spontaneous at high temperatures?
What is the most direct way for a student to determine if a chemical reaction in a closed system has reached equilibrium?
What is the most direct way for a student to determine if a chemical reaction in a closed system has reached equilibrium?
For the reaction $A^+(aq) + B^-(aq) \rightarrow AB(s)$, what is the best explanation for why increasing temperature increases the rate of the reaction?
For the reaction $A^+(aq) + B^-(aq) \rightarrow AB(s)$, what is the best explanation for why increasing temperature increases the rate of the reaction?
For the reaction $H_2 + I_2 \leftrightarrow 2HI$ (all gases) at equilibrium, the concentration of $I_2$ is 2M, $H_2$ is 2M, and $HI$ is 2M. What is the value of $K_c$?
For the reaction $H_2 + I_2 \leftrightarrow 2HI$ (all gases) at equilibrium, the concentration of $I_2$ is 2M, $H_2$ is 2M, and $HI$ is 2M. What is the value of $K_c$?
Which statement accurately describes the equilibrium constant, $K_c$?
Which statement accurately describes the equilibrium constant, $K_c$?
What does the double arrow ($ \leftrightarrow $) signify in a chemical equation for a reversible reaction?
What does the double arrow ($ \leftrightarrow $) signify in a chemical equation for a reversible reaction?
In the equilibrium constant expression ($K_c$), where is the concentration of products placed?
In the equilibrium constant expression ($K_c$), where is the concentration of products placed?
For the reaction $2SO_2(g) + O_2(g) \leftrightarrow 2SO_3(g) + heat$, which action will increase the concentration of $SO_3$?
For the reaction $2SO_2(g) + O_2(g) \leftrightarrow 2SO_3(g) + heat$, which action will increase the concentration of $SO_3$?
For the reaction $2SO_3(g) \rightarrow 2SO_2(g) + O_2(g)$, what is the correct equilibrium constant expression ($K_c$)?
For the reaction $2SO_3(g) \rightarrow 2SO_2(g) + O_2(g)$, what is the correct equilibrium constant expression ($K_c$)?
At 400°C in a 3.00 liter container, the following amounts are found: 0.0420 mole $N_2$, 0.516 mole $H_2$ and 0.0357 mole $NH_3$. What is the equilibrium constant, $K_c$ for $N_2(g) + 3H_2(g) \leftrightarrow 2NH_3(g)$?
At 400°C in a 3.00 liter container, the following amounts are found: 0.0420 mole $N_2$, 0.516 mole $H_2$ and 0.0357 mole $NH_3$. What is the equilibrium constant, $K_c$ for $N_2(g) + 3H_2(g) \leftrightarrow 2NH_3(g)$?
When a set amount of marble chips ($CaCO_3$) reacts with dilute hydrochloric acid, the reaction rate is too fast. What adjustment can be made to decrease the rate of reaction for the next trial?
When a set amount of marble chips ($CaCO_3$) reacts with dilute hydrochloric acid, the reaction rate is too fast. What adjustment can be made to decrease the rate of reaction for the next trial?
Flashcards
Entropy of Isolated System
Entropy of Isolated System
The entropy of an isolated system can never decrease.
Reversible Reaction at Equilibrium
Reversible Reaction at Equilibrium
At equilibrium, the forward and reverse reaction rates are equal.
Reaction with Decreased Entropy
Reaction with Decreased Entropy
N2(g) + 3H2(g) → 2NH3(g) is the most likely to have a decrease in entropy.
Increase in Entropy
Increase in Entropy
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Entropy and Equilibrium
Entropy and Equilibrium
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Second Law of Thermodynamics
Second Law of Thermodynamics
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Spontaneity and Thermodynamics
Spontaneity and Thermodynamics
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Reaction Spontaneity at High Temperatures
Reaction Spontaneity at High Temperatures
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Determining Equilibrium Achievement
Determining Equilibrium Achievement
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Effect of Temperature on Reaction Rate
Effect of Temperature on Reaction Rate
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Kc and Product Formation
Kc and Product Formation
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Double Arrow Meaning
Double Arrow Meaning
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Numerator
Numerator
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SO3 Concentration Increase
SO3 Concentration Increase
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Equilibrium Constant Expression
Equilibrium Constant Expression
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Decreasing the Rate of Reaction
Decreasing the Rate of Reaction
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Study Notes
- Entropy of an isolated system can never decrease.
- A reversible chemical reaction at equilibrium proceeds alternately in forward and reverse directions.
- A transformation that most likely involves a decrease in entropy is N2(g) + 3 H2(g) → 2NH3(g).
- When comparing reactions a and b, where (a) is O2(g) + N2(g) → N2O(G) and (b) is N2O(g) → O2(g) + N2(g), reaction b illustrates an increase in the entropy of the substance.
- The entropy of an isolated system always increases and becomes maximum at the state of equilibrium.
- The second law of thermodynamics states that when an isolated system undergoes a spontaneous change, the entropy of the system will increase.
- All options mentioned can be considered as an application of the entropy principle.
- A system with positive enthalpy and negative entropy will never be spontaneous.
- Reactions that are only spontaneous at high enough temperatures are those with ΔH+ and ΔS-.
- To determine if a chemical reaction has achieved equilibrium, measure concentrations of products and reactants over time.
- For the reaction A+(aq) + B-(aq) → AB(s), the best explanation for why increasing temperature increases the rate of reaction is that the average kinetic energy increases, so the likelihood of more effective collisions between ions increases.
- For the equilibrium reaction H2 + I2- ↔ 2HI (all gases), if the concentration of I2 is 2M, H2 is 2M, and HI is 2M, the value of Kc is 1.0.
- When Kc is very large, there are more products formed.
- The double arrow used in an equilibrium reaction means the rates are the same on the product and the reactant.
- In the equilibrium constant expression, the concentration of product is taken in the numerator.
- For the reaction 2SO2(g) + O2(g) ↔ 2SO3(g) + heat, increasing the pressure will increase the concentration of SO3.
- For the equation 2SO3(g) → 2SO2(g) + O2(g), the conventional equilibrium constant expression (Kc) is [ SO2 ]2 [ O2 ]/ [ SO3 ]2.
- For the reversible reaction N2(g) + 2H2(g) ↔ 2NH3(g) in a 3.00 liter container, with 0.0420 mole N2, 0.516 mole H2, and 0.0357 mole NH3 at equilibrium at 400°C, the value of Kc is 0.22.
- When a set amount of marble chips (CaCO3) is added to a small amount of dilute hydrochloric acid, using larger marble chips will decrease the rate of reaction the next time the experiment is performed.
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