Equilibrium Flashcards
(13 cards)
How does pressure/volume affect a chemical system at equilibrium?
-An increase in volume (decreasing pressure) will cause a shift towards the side with the larger number of moles of gaseous entities.
-A decrease in volume (increasing pressure) will cause a shift towards the side with smaller number of moles of gaseous entities.
-A system with an equal amount of gas on each side is unaffected by a change in volume/pressure. Same of systems with only liquid or solid entities.
-Adding or removing gases that are not involved in the reaction (inert gases) may change pressure but not affect equilibrium.
What is equilibrium?
-Forward reaction rate (collisions between reactants to form products) and the reverse reaction rate (collisions between products to form reactants) are occurring at the same time and rate.
-Assume any closed system with no visable changes is in a state of equilibrium.
How does a concentration change affect a chemical system at equilibrium?
-Adding a reactant to a system at equilibrium makes an equilibrium shift right (to the product). The forward reaction produces more product molecules to oppose the change introduced.
-Removing a products will also shift it to the right, producing more product molecules.
-Shifts away from the side you add.
-Shifts towards the side you removed from.
How does a temperature change affect a chemical system at equilibrium?
-Heat or cooling is like adding or removing from the system. If heat is added, equilibrium will shift away from the side with the energy term. If heat is removed the equilibrium will shift towards the side with the energy term.
How do your recognize a temperature change of a chemical system at equilibrium on a graph?
-No entities will “spike” at the line.
-At the line all will gradually increase/decrease after the disturbance.
-How do you recognize a concentration change of a chemical system at equilibrium in a graph?
-One reactant/product will “spike” instantaneously. (Line of disturbance).
How do you recognize a volume/pressure change of a chemical system at equilibrium on a graph?
-All gases spike at the disturbance.
What is the one change to a chemical system at equilibrium that can affect the value of Kc (equilibrium constant)? (Out of Concentration, temperature, and volume/pressure changes).
-Temperature change.
-Changes that make a reaction more products favoured will increase Kc values and vice versa.
What is La Chatelier’s principle?
-When a chemical system at equilibrium is disturbed by a change in property of the system (concentration, temperature and volume/pressure), the system will always react to oppose the change until a new equilibrium is reached.
Does a catalyst affect Kc (equilibrium constant) or cause an equilibrium shift?
-No, a catalyst only causes the system to reach a state of equilibrium faster.
When given the equilibrium constant (Kc) how can you determine if the reactants or products are favoured?
-If Kc is greater than 1, its product favoured.
-If Kc is less than 1, its reactants favoured.
-If the exponent is negative its reactant favoured.
-If the exponent if positive its product favoured.
-Ex. Kc=4.3 x 10^-3
It’s reactant favoured.
-The bigger the value of Kc is, the more the products are favoured at equilibrium.
What is the Bronsted and Lowry definition of acids and bases?
-Acids are H+ donators/proton givers.
-Bases are H+ acceptors/proton acceptors.
How is the Bronsted Lowry theory of an acid different than the modified Arrhenius?
-The modified Arrhenius definition did not account for non aqueous environments.
-The original Arrhenius definition did not explain weak bases.
