Equilibrium constants Flashcards
What is dynamic equilibrium?
Where the rate of forward reaction is equal to the rate of the reverse reaction and concentrations are constant.
What is LeChateliers principle?
If a system in dynamic equilibrium is subject to a change, then the equilibrium will shift to minimise the change.
What is Kc?
The equilibrium constant in terms of concentration, usually used for reactions in solution, although it can be used for any reaction.
What is Kp?
The equilibrium constant in terms of partial gas pressures, used for reactions only involving gases.
What is the equation for Kc?
Kc= [C]^c[D]^d / [A]^a[B]^b
What is the partial pressure?
The pressure exerted by each individual gas in the mixture.
What is partial pressure directly proportional to?
The concentration of gases in the mixture.
What is the equation for Kp?
Kp = pC^c pD^d / pA^a pB^b
If Kc=1?
The equilibrium has equal amounts of reactants and products.
If Kc<1?
Few products are formed, most of the equilibrium mixture is reactants.
If Kc>1?
Most of the reactants in the equilibrium mixture have been converted into products.
What does equilibrium data tell us?
The relative stability of the reactants and products, and the free energy changes that occur between them.
What does reaction rate tell us?
The changes that occur during the reaction, and the order in which individual bonds and broken and made, called the reaction mechanism.
What are all considered in an industrial process?
Equilibrium yield
Rate of reaction
Energy calculations
What must any industrial reaction aim to do?
Produce the maximum amount of product as quickly as possible with the efficient use of energy to reduce costs.
How can equilibrium yield of product be maximised?
By altering concentration, pressure, or temperature.
How can the rate of reaction be maximised?
By increasing temperature, pressure, or adding a catalyst.
How can energy calculations be used in industrial processes?
To identify how much energy needs to be input into the system for a reaction to occur, minimising the input of excess energy.
The energy generated by an exothermic reaction may be calculated and this allows a company to decide whether it is economical to harness this energy.
What is the only thing that affects equilibrium constants?
Temperature.
For an exothermic reaction in dynamic equilibrium, what happens when temperature is increased?
An increase in temperature will cause the equilibrium to shift in the endothermic direction, reducing the amount of products and increasing the amount of reactants. This decreases Kc and Kp.
For an endothermic reaction in dynamic equilibrium, what happens when temperature is increased?
An increase in temperature will cause the equilibrium to shift in the endothermic direction, increasing the amount of products and decreasing the amount of reactants. This increases Kc and Kp.
How can you calculate partial pressure?
Partial pressure = % of a particular gas x pressure
Partial pressure = pressure of a particular gas in a mixture
