Changing the conditions of an equilibrium reaction 2 Flashcards
Pressure. Temperature + Catalysts
Do pressure changes affect all reactions?
No, pressure changes only affect reactions involving gases
When will changing the pressure affect the position of equilibrium in a gaseous reaction?
Only if there is a different number of gas molecules on either side of the equation
What happens to the equilibrium when the pressure is increased?
The equilibrium moves to the side with fewer gas molecules, reducing the pressure
What happens to the equilibrium when the pressure is decreased?
The equilibrium will move to the side with more gas molecules, increasing the pressure
What happens to the equilibrium in the reaction N2O4(g) ↔ 2NO2(g) when the pressure is decreased?
The equilibrium will shift to the right producing more NO2, which increases the pressure
How is increasing the pressure a gas similar to increasing the concentration of a solution?
Increasing the pressure means there are more gas molecules in a given volume, just like increasing concentrations means more solute particles in a given volume
What happens to the equilibrium in the reaction N2O4(g) ↔ 2NO2(g) when the pressure is increased?
The equilibrium will shift to the left because there are fewer gas molecules (N2O4 - 1 mole) on that side, reducing the pressure
What happens to the equilibrium position if there is the same number of gases on both sides of the equation?
The equilibrium position does not change when pressure is altered
Why does pressure have no effect on equilibrium if there are equal moles of gases on both sides?
Changing the pressure does not favour either side, as both sides exert the same number of gas molecules
What is the relationship between exothermic and endothermic reactions in a reversible reaction?
Reversible reactions that re exothermic in one direction are endothermic in the other direction
How does the enthalpy change compare for the forward and reverse reactions?
The size of enthalpy change is the same for both directions, but the sign changes
What happens if you increase the temperature of an equilibrium mixture where the forward reaction is exothermic?
The equilibrium shifts to the left (endothermic direction) to absorb the added heat
Why does the equilibrium shift to the endothermic direction when the temperature is increased?
According to Le Châtelier’s principle, this is done to oppose the temperature increase by absorbing the heat
How does increasing the temperature affect the proportions of products and reactants in an exothermic forward reaction?
The proportion of reactants increases, and the proportion of products decreases
What happens to the equilibrium if you decrease the temperature in a reaction exothermic in the forward direction?
The equilibrium shifts to the right (exothermic direction), producing more products
What does the negative ΔH value indicate about a reaction?
What does the positive ΔH value indicate about a reaction?
It means the forward reaction is exothermic, releasing heat. It means the forward reaction is endothermic, absorbing heat
What happens to the equilibrium when the temperature is decreased in an exothermic reaction?
The equilibrium shifts to the right (exothermic direction), releasing heat
Why does the equilibrium move in the endothermic direction when the temperature increases?
To release heat and counteract the temperature drop
Do catalysts affect the position of equilibrium?
No, catalysts do not affect the position of equilibrium or the composition of the equilibrium mixture
How do catalysts speed up a reaction?
Catalysts provide an alternative reaction pathway with a lower activation energy for the reaction
What is the primary benefit of using catalysts in equilibrium reactions?
Catalysts reduce the time needed to reach equilibrium, making processes more efficient
How do catalysts affect the forward and backward reactions in a reversible reaction?
Catalysts affect the forward and backward reactions equally, increasing the rate of both