CH106 Physical Chemistry Flashcards
When is a chemical reaction said to be at equilibrium?
When the rates of both the forward and backward reactions are equal.
What is the equilibrium constant expression?
When calculating equilibrium constants, what should the units be converted to?
Moles
How would you calculate the equilibrium constant of the backward reaction?
Either take the reciprical of the forward reaction (1/K) or flip the equation.
If all the stoichiometry of a reaction was multiplied by “n” what would the expression be to calculate the equilibrium constant?
What occurs when
k<1
k>1
k=1
The point of equilibrium lies to the left
The point of equilibrium lies to the right
The reaction is at equilibrium
What is homogeneous equilibrium?
This is where all the reactants and products are in the same state.
What is heterogeneous equilibrium?
This is where the reactants nad products are in different states
In heterogeneous equilibrium, what are the values taken for pure liquids and solids?
They are taken as having a value of 1 and thus can be disregarded from the expression
What is an exothermic reaction?
A reaction that gives out heat (energy) -ve enthalpy
What in an endothermic reaction?
A reaction that absorbs heat (energy) +ve enthalpy
Whats is Le Chatelier’s Principle?
If a system is disturbed its composition of the system will change in a way to minimise the effect.
What is a key point about enthalpy the change in enthalpy that must be considered?
The total change in enthalpy only depends on where we start and where we end. Change is independant of the pathway taken.
What is the first law of thermodynamics?
The total energy of an isolated system is constant.
