E Cell as an Intensive Property
Intensive properties are those that do not depend on the amount of substance present. The electromotive force (E Cell) of an electrochemical cell is considered an intensive property because:
- Intrinsic Nature: E Cell is determined by the inherent characteristics of the materials involved (electrodes and electrolyte) and their reactions.
- Independence from Quantity: The voltage produced by the cell remains constant regardless of the amount of reactants present in the cell. Whether you have a small or large quantity of reactants, the E Cell value will remain the same as long as conditions (like temperature and pressure) are constant.
∆rG of Cell Reaction as an Extensive Property
Extensive properties, in contrast, depend on the amount of substance present. The Gibbs free energy change (∆rG) for a cell reaction is an extensive property due to:
- Direct Relation to Amount: ∆rG is proportional to the number of moles of reactants and products. More reactants will yield a larger value of ∆rG.
- Energy Consideration: As more material is involved in the reaction, the total energy change associated with the reaction increases, reflecting the larger scale of the process.
Summary
- E Cell:
- Intensive property
- Independent of the amount of reactants
- ∆rG:
- Extensive property
- Dependent on the quantity of reactants involved
Understanding these distinctions is crucial in electrochemistry as they help in predicting how cells will operate under varying conditions.