Equations 18.10 and 19.3 to calculate the emf values of the Daniell cell at
Interpretation:
The EMFvalues of the cell at the temperatures of
Concept introduction:
Entropy
Enthalpy
Answer to Problem 68AP
Solution: The EMFof the cell at a temperature of
The EMFof the cell at a temperature of
Explanation of Solution
The standard free energy change as follows:
Here,
Substitute the value of
Here,
The considered reaction is:
The change in the enthalpy of the reaction is as follows:
Here,
The standard enthalpies of the formation of
Substitute the values in the above equation:
Thus, the standard enthalpy of formation is
The change in the entropy of the reaction is as follows:
Here,
The standard entropies of the formation of
Substitute the values in the above equation:
Thus, the standard entropy of formation is
Substitute the values of the standard entropy of formation and the standard enthalpy of formation in equation
At a temperature of
Therefore, the EMFof the cell ata temperature of
Ata temperature of
Substitute the value of the standard entropy of formation and the standard enthalpy of formation in equation
Therefore, the EMFof the cell ata temperature of
In this calculation, the value of theEMFof the cell does not depend on the temperature, but, in practice, the value of theEMFof the cell does decrease with temperature. This is because the assumption used in the derivation is that
The EMF valuesof the cell at the temperatures of
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Chapter 19 Solutions
Chemistry
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