Chemistry Topic 7 Flashcards
Equilibrium
At equilibrium the rate of the forward and reverse reactions are _____ and the concentrations are _____
equal; constant
True or false: A closed system must be used in order to obtain equilibrium
True!
What are the only two phases of substances that can be included in the equilibrium expression?
Gases and aqueous
How do you find the K value when a whole reaction is multiplied by a number?
You raise K to that number
What direction will the reaction go if Q is greater than K?
Reverse - The initial concentrations of the products are too high, they need to decrease to reach equilibrium, so they become the reactants
What direction will the reaction go if Q is less than K?
Forward - The initial concentrations of the products are too low, they need to increase to reach equilibrium, so the reaction stays the same
What does Q stand for?
Reactant quotient
What does Le Chatelier’s Principle state?
When a reaction is at equilibrium and a change is made, the reaction will respond to minimize the effect of the change
Le Chatelier’s Principle
What happens when you add more reactant?
The concentration of the product increases
Le Chatelier’s Principle
What happens when you add more product?
The concentration of the reactant increases
Le Chatelier’s Principle
What happens if you remove a reactant?
The concentration of the reactants will increase
Le Chatelier’s Principle
What happens if you remove a product?
The concentration of the product increases
Le Chatelier’s Principle
What types of reaction does pressure only affect?
Gaseous!
Le Chatelier’s Principle
What happens when you increase the pressure?
(There are gases)
The reaction shifts from the side with more moles to less moles of gas
Le Chatelier’s Principle
What happens when you decrease the pressure?
(There are gases)
The reaction will shift from less moles to more moles of gas
What is the only thing that can affect the equilibrium constant?
Temperature!!!!
Le Chatelier’s Principle
If reaction is exothermic, what happens if temp increases?
Include what happens to the K value
The reactant will increase and the K value will decrease
Le Chatelier’s Principle
If reaction is exothermic, what happens if temp decreases?
Include what happens to the K value
The product will increase and the K value will increase
Le Chatelier’s Principle
If reaction is endothermic, what happens if temp increases?
Include what happens to the K value
Product will increase and K value will increase
Le Chatelier’s Principle
If reaction is endothermic, what happens if temp decreases?
Include what happens to the K value
Reactant will increase and K value will decrease
Le Chatelier’s Principle
How does a catalyst affect the equilibrium and equilibrium constant
It doesn’t!
It just makes the reaction happen faster
Can energy enter or leave a closed system at equilibrium?
No!
What is the one thing you really need to pay attention to when solving with R, G, H or S?
Units!
When delta G is negative, the reaction is (spontaneous / non spontaneous)
Spontaneous!
When delta G is positive, the reaction is (spontaneous / non spontaneous)
Non spontaneous!
What does it mean if delta G is at 0?
The reaction is at equilibrium
If delta G is negative, what K value (>1 or <1) will favor the product of the reaction?
A K value greater than 1 (>1) will favor the product with a negative delta G
If delta G is positive, what K value (>1 or <1) will favor the reactant of the reaction?
A K value less than 1 (<1) will favor the reactant with a positive delta G
What is entropy at when the reaction is at equilibrium?
Its maximum
What is the equation to solve for the delta H of a reaction
Delta H products - Delta H reactants = Delta H reaction
This is the same for finding the delta S
Use collision theory to explain why increasing the temp increases the rate of a certain reaction
The particles collide more frequently with greater energy, allowing for more effective collisions and a faster reaction
True or False: The rate is increased by the same amount for the forwards and reverse reaction with a catalyst
True!
Define dynamic equilibrium
When the rates of forward and reverse reactions are equal
True or False: When the rate of evaporation equals the rate of condensation in a particular reaction, does that mean its at equilibrium?
Yes! The forwards and reverse rates are equal
When at phase equilibrium, will the amounts of liquid and gas present change?
No
For a reaction, if the K increases when temp increases is it endo or exothermic? Explain
Endothermic because as temp increases you get more products
How do entropy and Gibbs free energy change as a system moves towards equilibrium?
Gibbs free energy (delta G) approaches minimum and entropy approaches maximum.
