Chemical reactions are controlled by thermodynamics and kinetics. Thermodynamics determines if a reaction is favored to occur, while kinetics determines if the reaction will occur on a reasonable time scale. The thermodynamic favorability of reactions is controlled by changes in entropy and enthalpy, and the temperature at which the reaction takes place. Gibb's Law of Thermodynamics is a function that relates these three factors, which are important in determining the spontaneity of a chemical reaction. When the free energy of a reaction becomes negative, the reaction is spontaneous.
This module explores the relationship between the thermodynamic properties of reactions, enthalpy, entropy, and free energy. Plots of free energy as a function of temperature are constructed for several different reactions, each of which has different changes in entropy and enthalpy values. Note that the calculations used here assume that the values of enthalpy and entropy from reactions are independent of temperature. While this assumption leads to free energy values close to the correct values, it is not strictly true.
INSTRUCTIONS
1. Select a reaction by clicking on one of the five Reaction option buttons.
2. Select a temperature value by adjusting the temperature from 0 to 1500. K
using the Temperature scroll bar.
3. To clear the plot area, click on the Clear Plot button.
4. To begin a new experiment, select another reaction option buttons.
