Consider the system
2N2O5(g) <----> 2N2O4(g) + O2(g) + heat
at equilibrium at 25�C. If the temperature
were raised would the equilibrium be shifted to produce more N2O5 or more N2O4?
1. more N2O4
2. more N2O5
3. There would be no effect.
Just remember this about Le Chatelier's Principle. When a system at equilibrium is disturbed it will shift so as to undo what we've done to it.
So if we add heat the system will shift to use up the heat. Which way is that?
it would make more N2O5?
Right you are. Very good.
To determine how the equilibrium will shift when the temperature is raised, we need to consider the reaction's enthalpy (∆H) value. The enthalpy change can be used to predict the direction of the shift according to Le Chatelier's Principle.
In this case, the given reaction is an exothermic reaction because heat is being released as a product. A decrease in temperature will favor the exothermic reaction. Therefore, raising the temperature will favor the endothermic reaction (the one absorbing heat), which is the formation of N2O5.
To understand this concept in more detail, we can look at the reaction's heat term. The heat term, located on the right side of the reaction, indicates the direction in which the equilibrium will shift when there is a change in temperature. In this case, since heat is a product, an increase in temperature will cause the reaction to shift in the reverse direction, favoring the reactants.
Therefore, when the temperature is raised, the equilibrium will shift to produce more N2O5 (option 2).