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Effect of temperature of equilibrium con...

Effect of temperature of equilibrium constant is given by `logK_(2)-logK_(1)=(-DeltaH)/(2.303R)[(1)/(T_(2))-(1)/(T_(1))](" where "T_(2)gtT_(1))`. Then for a endothermic reaction the false statement is

A

`[(1)/(T_(2))-(1)/(T_(1))]=" positive"`

B

`logK_(2)gt logK_(1)`

C

`DeltaH=" positive"`

D

`K_(2)gtK_(1)`

Text Solution

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The correct Answer is:
To solve the question regarding the effect of temperature on the equilibrium constant for an endothermic reaction, we will analyze the given equation and the implications of the statements provided. ### Step-by-Step Solution: 1. **Understanding the Van 't Hoff Equation**: The equation given is: \[ \log K_2 - \log K_1 = \frac{-\Delta H}{2.303R} \left( \frac{1}{T_2} - \frac{1}{T_1} \right) \] where \( K_1 \) and \( K_2 \) are the equilibrium constants at temperatures \( T_1 \) and \( T_2 \) respectively, \( \Delta H \) is the change in enthalpy, and \( R \) is the ideal gas constant. 2. **Identifying the Reaction Type**: For an endothermic reaction, \( \Delta H \) is positive. This means that as temperature increases, the equilibrium constant \( K \) should also increase, indicating that the forward reaction is favored. 3. **Analyzing the Temperature Condition**: The condition states that \( T_2 > T_1 \). Therefore, the term \( \left( \frac{1}{T_2} - \frac{1}{T_1} \right) \) will be negative because \( \frac{1}{T_2} < \frac{1}{T_1} \). 4. **Substituting into the Equation**: Since \( \Delta H \) is positive for an endothermic reaction, the left side of the equation must also be positive for the equation to hold true. Thus: \[ \log K_2 - \log K_1 = \text{positive} \] implies that \( K_2 > K_1 \). 5. **Evaluating the Statements**: - **Statement 1**: If the reaction is endothermic, the statement that the difference in temperatures leads to a negative value is incorrect. This implies that the statement is false. - **Statement 2**: \( K_2 > K_1 \) is true for an endothermic reaction as explained. - **Statement 3**: \( \Delta H \) should be positive for an endothermic reaction, which is also true. - **Statement 4**: The relationship between \( K \) and temperature for endothermic reactions holds true. 6. **Conclusion**: The false statement regarding the endothermic reaction is the first one, as it incorrectly interprets the relationship between temperature and the equilibrium constant. ### Final Answer: The false statement regarding the endothermic reaction is **Statement 1**. ---
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