Equilibrium Flashcards
What can be changed in a reaction to alter the equilibrium position?
Concentration, temperature, pressure/volume (only applies to gases)
What is meant by an “open system”?
An open system allows matter and energy to be exchanged with the surroundings
What happens to the equilibrium position when the product concentration is increased?
The reverse reaction increases and equilibrium moves to the left
Are all reactions reversible?
No, for example due to the formation of energetically stable products or loss of products into the environment
What does Le Chatelier’s principle state?
If an equilibrium system is subjected to a change, the system will adjust itself to partially oppose the effect of the change
What is a “closed system”?
A reaction vessel that does not allow the reactant or product particles to escape
What happens to the equilibrium position when the reactant concentration is increased?
The forward reaction increases and equilibrium moves to the right
Give an example of an “open” system.
A flask with no lid that allows heat and gas products escape
On an equilibrium graph how do you know the reaction has reached equilibrium?
When equilibrium is
established the
concentration lines are
horizontal
What type of system is it when energy can escape but not matter?
Closed system
What is meant by the term “reversible reaction”?
Reactions in which the conversion of reactants to products and products to reactants occur simultaneously.
What can you measure using observation in equilibrium reactions?
You can observe whether the forward or reverse reaction has occurred if the reactants and products have different colours
Are physical changes reversible?
Generally they are reversible as chemical bonds remain unchanged
In a reaction where a gas is produced what type of system is required for equilibrium to be reached?
A closed system
Why is a substance in a system more likely to react when the temperature is higher?
The particles of that substance have more kinetic energy, causing them to collide more often with the other particles in the system, making the reaction occur
What does Kc represent?
The equilibrium constant
How are equilibrium reactions symbolised?
Equilibrium reactions are symbolised by ⇌
When is a state of dynamic equilibrium reached?
A state of equilibrium is reached when the rate of the forward and reverse reactions are equal
What is activation energy?
The minimum amount of energy required in the collision between reactants for a reaction to occur
How can you measure
the concentration of
an equilibrium using
pH?
You can measure the change in pH and calculate the H3O+ concentration, then use simple stoichiometry
Can forward and reverse reactions occur at the same time?
Yes, a forward and reverse reaction can occur at the same time if the reaction occurs within a closed system
Is the equilibrium constant value largest when the concentration of reactants is larger than the products?
No
What is the impact on the equilibrium position when a catalyst is added to a reaction in a closed system?
There is no impact on the equilibrium position. Equilibrium will only be reached faster
What concentrations are not included when calculating the equilibrium constant?
Concentrations of pure liquids and solids are not included, water is only included if it is a product such as in condensation reactions
What energy is required to remove an electron from an element?
First ionisation energy
“True or False? The stronger the electronegativity, the more readily the element will accept electrons.”
True
Where can the elements with the lowest ionisation energy be found on the periodic table?
“Bottom left e.g. Cs, Rb, Ba”
If Kc is larger than 104 is there significantly more reactant or product?
Product
What kind of ionisation energy makes elements lose electrons more readily?
Low ionisation energy
“True or false? Is the
Kc of a reaction
temperature
dependent?”
True
What does RICE stand for?
Reaction, initial concentration, change in concentration, equilibrium concentration
What happens to the equilibrium position for an endothermic reaction when heat is added?
The equilibrium position will move towards the product side as heat is stored in the molecule
What can you do to increase the concentration of gas in a closed system?
Decrease the volume
