Equilibria Flashcards
(27 cards)
What is K?
K = constant, tells us whats going on in a chemical reaction
When does equilibrium occur?
When concentration becomes constant
How do we measure point of equilibrium?
aA + bB ⇋ cC + dD
K = [C]ᶜ[D]ᵈ
[A]ᵃ[B]ᵇ
ratio of products and reactants
What if the top line is bigger?
K = [C]ᶜ[D]ᵈ
[A]ᵃ[B]ᵇ
Assume that 1 < X
What if the top line is smaller?
K = [C]ᶜ[D]ᵈ
[A]ᵃ[B]ᵇ
Assume that 1> X
What happens with a large value K?
Product favoured, gone to completion
What happens with a small K value?
Reactant favoured and virtually does not happen
What do these mean?
K, K = ½, K = (½)²
Constant, reversed reaction of K, K scaled x2.
e.g K = 3, reverse is K = ⅓, Scaled 2x = (⅓)² = ⅑
What is the K equation for solids and pure liquids?
There is no K in this sense, for we cannot workout the concentration.
What is Q?
Q represents the reaction quotient, which is a measure of the relative amounts of reactants and products present at any given time in a reaction. It tells you whether a system is at equilibrium
What can we use to measure Q?
Quotient.
Q = [C]ᶜ[D]ᵈ
[A]ᵃ[B]ᵇ
What happens if K = Q?
System is at equilibrium
What happens if Q>K?
Q is bigger than K, implies we need to make more reactants by moving reaction towards reactants to re-establish equilibrium.
What happens if Q<K?
Q is smaller than than K, implies we need to make more products by moving reactions towards products to get back to equilibrium
What is Le Chateliers principle?
If a stress is applied to a system in dynamic equilibrium, the system will adjust to relieve that stress. The position shifts to counteract the change to re-establish an equilibrium
What are some factors that affect rate of reaction?
Speed, pressure, concentration, temperature
What happens if we change the pressure of a system?
By using a smaller container, we increase the pressure to shift to equilibrium
What happens when we increase temperature in endothermic reaction?
Size of K increases, moves reaction to make more products
What happens when we increase temperature in exothermic reaction?
Size of K drops, moves reaction to make more reactants
What is Ksp?
The solubility of the product. The greater the value of Ksp, the more soluble the compound
What is common ion effect?
Reduction in solubility of a dissolved salt when another compound which shares a common ion is added to the solution. The reaction will reverse by pushing equilibrium to make more reactants.
What is the equilibrium constant for solubility product?
Ksp, the greater the value of Ksp, the more soluble
The solubility of AgCl in water is 1.35x10⁻⁵ mol L⁻¹, what is the Ksp of the ions?
Ksp= [Ag⁺] [Cl⁻] =
(1.35x10⁻⁵) x (1.35x10⁻⁵) =
1.8x10⁻¹⁰
The Ksp for [Ag⁺] and [Cl⁻] is 1.8x10⁻¹⁰, How do we find the Ksp of the parent compound?
Ksp = [Ag⁺] [Cl⁻] = 1.8x10⁻¹⁰
[s]² = 1.8x10⁻¹⁰
√1.8x10⁻¹⁰ = 1.35x10⁻⁵
