Lecture 7 Flashcards
When do we use Kc?
When the equilibrium constant is defined in terms of concentrations
What can we use to quantify a system at equilibrium?
The equilibrium constant (Kc or Kp)
When do we used Kp?
When the equilibrium constant is defined in terms of pressure
If there the forward and reverse reactions are both occurring at equilibrium, what is happening to the species?
Their rates are identical so there is no net change in composition
Does it matter if an equilibrium reaction starts with the reactants or the products?
No the equilibrium composition will be the same regardless
What is c (degree sign circle)?
Standard concentration
= 1 molL -1
What is p (degree sign circle)?
Standard pressure
= 1 x 10^5 Pa
= 1 bar
What do standard pressure and concentration do?
Strip equilibrium of units
Makes it dimensionless
What does standard pressure and concentration mean for Kc and Kp?
We can simplify expressions for Kc but not Kp
When writing equilibrium constants, where do products and reactants go?
Products top
Reactants bottom
What is Dave’s Dogma?
Products raised to stoichiometric powers
Divided by reactants raised to theirs
Pure solids and pure liquids do not appear
What does the value of K give information about?
The extent of reaction at equilibrium
If the Kc is small where does the equilibrium lie?
Far to the left
When doing a concentration table when is it important to do a negative sign?
In the change in concentration row, the difference if it is less
If Kc is large where does the equilibrium lie?
To the right
