Chemistry Unit 3 Flashcards
Chemical equilibrium
when the rate of forward reaction = rate of reverse reaction and the concentration of reactants remain unchanged
Dynamic equilibrium
rate of forward reaction = rate of reverse reaction
Extent of reaction
how much of a product is formed when a system reaches equilibrium
(⇌)
a reversible process
Reversible reactions occur
simultaneously in both directions
Relative ratio of reactants to products at equilibrium
different for different reactions
Rate of reaction
a measure of the change in concentration of reactants over time
In a closed system
only energy is exchanged with surroundings
In an open system
both energy and matter are exchanged with surroundings
Irreversible reaction
products cannot react together to be converted back into reactants
Position of equilibrium can be modified by
adding or removing a product/reactant, change in pressure, concentration or temperature
Le Chatelier’s Principle
when a stress is applied to a system in a state of equilibrium, the system reacts in a way to reduce the stress
At equilibrium, the concentrations of products and reactants
remain the same unless a stress is applied to the system
Examples of added stress to a system:
add/remove a chemical, increase/decrease in pressure or temperature
If a chemical added to a system
the system shifts away from the chemical and vice versa
If pressure is added to a system
the system will shift to the side with the least number of gas particles and vice versa
Heating an exothermic reaction
system shifts to the left, favouring the reactants as high energy, and giving more energy to product particles to overcome activation barriers
Heating an endothermic reaction
system shifts to the right, favouring the products as high energy, and giving more energy to reactant particles to overcome activation barriers
Pressure (Pa) =
force (N) / area (m^2)
Higher temperatures
more particle movement and increased collisions
Lower temperatures
less particle movement and decreased collisions
Increased pressure
increased collisions and faster forward rate of reactions
Increasing pressure by adding an inert gas
The concentration of reactants and products is not changed nor is equilibrium affected
Increasing concentration in collision theory
Equal to increasing pressure
