Equilibrium II Flashcards
(11 cards)
What are the steps to calculating Kc?
- Calculate concentration of reactants and products
- Write balanced chemical equation
- Write equilibrium constant for reaction
- Substitute equilibrium concentrations into expression
What state are the reactions in Kp expressions?
Gas states
What is the equilibrium expression in terms of the partial pressure of gases?
PcC(g)eqm x PdD(g)eqm/
PaA(g)eqm x PbB(g)eqm
PaA and PbB = equilibrium reactant partial pressure
PcC and PdD = equilibrium product partial pressure
What are ignored in Kp equilibrium expressions?
Solids and liquids - in hetergeneous reactions
When is the only time the Kp of a reaction changes?
If the temperature of the reaction changes - otherwise it is constant
What happens if a Kp question only gives the number of moles of gases present anf the total pressure?
- Calculate total no moles
- Calculate mole fractions
- Use mole fraction to calculate pressure of each element or compound
What happens to the value of Kc and Kp if the temperature increases and it is an endothermic reaction?
Equilibrium constant increases
(likewise, if temperature decreases, equilibrium constant decreases)
What happens to the value of Kc and Kp if the temperature increases and it is an exothermic reaction?
Equilibrium constant decreases
and vice versa if temperature decreases
(conc of reactants increase while that of products decrease)
What does a change in pressure only affect?
Position of equilibrium
Why is the value of Kp not affected by pressure?
Changes in pressure cause a shift in the position of equilibrium to a new position which restores the value of Kp
How does the presence of a catalyst affect Kc and Kp?
If all other conditions stay the same, Kp and Kc are not affected by this - (catalysts only cause a reaction to reach equilibrium faster)
