- AStatement 1 is True, Statement 2 is True; Statement 2 is correct explanation for Statement 1.
- BStatement 1 is True, Statement 2 is True; Statement 2 is NOT correct explanation for Statement 1.
- CStatement 1 is True, Statement 2 is False.
- DStatement 1 is False, Statement 2 is True.
View written solutionFree
Correct answer: D
Analysis of Statement 1
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Statement 1: For every chemical reaction at equilibrium, standard Gibbs energy of reaction is zero.
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Let's consider the relationship between the Gibbs energy of reaction () and the standard Gibbs energy of reaction (\\\Delta_r G^\\circ). The equation is given by: where is the gas constant, is the absolute temperature, and is the reaction quotient.
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At equilibrium, two conditions are met:
- The Gibbs energy change for the reaction is zero: .
- The reaction quotient is equal to the equilibrium constant : .
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Substituting these equilibrium conditions into the equation, we get: Rearranging this gives the relationship between the standard Gibbs energy and the equilibrium constant:
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From this equation, we can see that the standard Gibbs energy of reaction, \\\Delta_r G^\\circ, is zero only if , which implies that the equilibrium constant .
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However, a chemical reaction can be at equilibrium with any value of (i.e., , , or ). It is not necessary for to be 1 for every reaction at equilibrium.
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Therefore, the statement that \\\Delta_r G^\\circ is zero for every chemical reaction at equilibrium is false. It is (the Gibbs energy change under the specific equilibrium conditions) that is zero, not necessarily \\\Delta_r G^\\circ (the standard Gibbs energy change).
Analysis of Statement 2
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Statement 2: At constant temperature and pressure, chemical reactions are spontaneous in the direction of decreasing Gibbs energy.
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This statement describes the fundamental criterion for spontaneity of a process under conditions of constant temperature and pressure. The change in Gibbs energy, , determines the direction of a spontaneous process.
- If (negative), the process is spontaneous in the forward direction. A negative signifies a decrease in the system's Gibbs energy.
- If (positive), the process is non-spontaneous in the forward direction, but the reverse process is spontaneous.
- If , the system is at equilibrium, and there is no net change.
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Thus, a chemical reaction will proceed spontaneously in the direction that leads to a decrease in the Gibbs energy of the system.
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Therefore, Statement 2 is true.
Conclusion
- Statement 1 is False.
- Statement 2 is True.
Based on this analysis, the correct option is the one that identifies Statement 1 as false and Statement 2 as true.
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