Equilibria I Flashcards
What is dynamic equilibrium?
When the forwards and reverse reactions of a reversible reaction are occurring at the same rate, so there is no net further change in the concentrations of the reactants or products.
What conditions are required for a reaction to come to dynamic equilibrium?
The reaction must be reversible and it must be run in a sealed container (so that no reactants or products can leave and nothing else can get in).
What effect does changing the concentration of the reactants/products have on the position of equilibrium?
Increasing the concentration of one or more of the reactants favours the forward reaction, shifting equilibrium to the right. Increasing the concentration of the products does the opposite.
What effect does changing the pressure have on the position of equilibrium?
For gaseous equilibria, increasing the pressure favours the side of the reaction with fewer moles of gas produced, which reduces the pressure.
What effect does changing the temperature have on the position of equilibrium?
Increasing the temperature favours the forwards reaction if the forwards reaction is endothermic, and the reverse reaction of the forwards reaction is exothermic. The opposite happens for a decrease in temperature.
What effect does the addition of a catalyst have on the position of equilibrium?
Adding a catalyst does not affect the position of equilibrium. It does however, increase the rate at which equilibrium is attained by increasing both the forwards and reverse reaction rates equally.
What is a homogenous system?
A system in which all components are in the same phase.
What is a heterogenous system?
A system where at least two different phases are present.
What is the equilibrium constant?
The equilibrium constant is a measure of the position of equilibrium. If it’s value is less than 1, equilibrium lies to the left, if it equals one, the reactants and products are in a 1:1 ratio, if it is more than 1 equilibrium lies to the right.
How do you write out the expression for an equilibrium constant?
For the equilibrium aA + bB <—> cC + dD the equilibrium constant is Kc = [A]^a [B]^b / [C]^c [D]^d (solids are not written in these equations)
