LT#3: Kc Calculations Flashcards
What does the Law of Equilibrium state?
Even if you start with different concentrations, there is a constant ratio between the equilibrium concentrations of reactants and products for each particular reaction.
Define Equilibrium Expression
The equation used to calculate an equilibrium constant.
If the molar concentrations of all the chemicals at equilibrium are used, the equilibrium constant is called…
Kc
If K is > 10^10
The system essentially contains only products.
The forward reaction goes to completion, and the reverse occurs very rarely.
The equilibrium position is far to the right.
If K is > 1
The system has more products than reactants.
The forward reaction is more favourable than the reverse.
The equilibrium position is to the right.
If K is = 1
The system has equal amounts of products and reactants.
The forward and reverse reactions are equally favourable.
If K is < 1
The system has more reactants than products.
The reverse reaction is more favourable then the forward.
The equilibrium position is to the left.
If K is < 10^-10
The system essentially contains only reactants.
The reverse reaction goes to completion, and the forward occurs very rarely.
The equilibrium position is far to the left.
How are the equilibrium concentrations of chemicals experimentally measured?
By their colour, pH or pressure.
What does the ICE in ICE Table mean?
Initial Concentration, Change in Concentration and Equilibrium Concentration.
Describe how ICE tables are filled in
Start by determining the change in concentration for a chemical that starts at 0M.
Use mole ratios to convert this change into other chemical. When crossing over the reaction arrow, flip signs.
Determine the E concentrations by I + C.
What is the general formula for writing an equilibrium expression?
Kc = [Products]/[Reactants] raised to their coefficients in the balanced chemical equation.
What assumption can be made during calculations if K is really small?
If the lowest [initial] concentration divided by K is > 500, x is so small the [initial] - x = [initial].
