What is a Dynamic equilibrium?
a balance between forward and reverse processes that are occurring simultaneously at equal rates (no observable change occurs)
What is Static equilibrium?
Irreversible reactions where reactants no longer turn into products
What is Chemical Equilibrium?
The state of a reaction in which all reactants and products have reached constant concentrations in a closed system
What is the Equilibrium position?
the relative concentrations of reactants and products in a dynamic system
What does the K value indicate in relation to 1?
- If K>1 🡪 The reaction proceeds towards completion. The concentration of the products is much higher than the concentration of reactants at equilibrium
- If K = 1 🡪 The concentrations of reactants and products are approximately equal at equilibrium
- If K<1 🡪 Very small amount of products are formed. The concentration of the reactants is much larger than the concentrations of products at equilibrium
Why are the concentrations of solids and liquids not included in the equilibrium expression law?
the concentrations of pure solids and liquids cannot change (are constant)
To simplify the equilibrium law equation, all constants are incorporated together with K
What is the quotient and what does its values mean?
- Q is used to figure out which direction the equilibrium will shift.
- If Q = K The system is at equilibrium
- If Q < K: The system will shift towards the products because not enough product has formed
- If Q > K: The system will shift towards the reactants because too much product has formed / passed equilibrium
What is the hundred rule?
divide initial concentration of reactants by k value
- if more than 100 then value can be ignored
- If less than 100 then the value cannot be ignored (% error is less than 5%)
What does it mean if K increase? decrease?
- Increase in K means equilibrium has shifted to the product side (right)
- Decrease in K means equilibrium has shifted to the reactant side (left)
What is molar solubility?
amount of material able to dissolve in 1 mol of solvent per litre to create a saturated solution
What is Ksp?
- equilibrium constant of a dynamic equilibrium between a solute and a solvent in a saturated solution (sparingly/slightly soluble salts)
- Dependant on temperature
What is the common ion and how does it reduce solubility?
A common ion is an ion that is present in two different solutes. Its presence decreases
the solubility of the less-soluble substance because it shifts the equilibrium toward the
solid (left because supersaturated).
What does a larger and smaller Ksp value mean?
- smaller Ksp = less soluble in water
- larger Ksp = more soluble in water
What is the reaction quotient used for?
predict whether a precipitate will form or not when solutions are mixed for slightly soluble salts
What is the relationship between Qsp and Ksp?
- Qsp > Ksp: supersaturated solution. Too much product has been formed. equilibrium shifts to the left and a precipitate is formed.
- Qsp = Ksp: Saturated solution at equilibrium, no precipitate forms and no more solid dissolves
- Qsp < Ksp: unsaturated solution. Not enough reactant has been converted to product. equilibrium will shift to the right, no precipitate forms and more solid can dissolve.
What is Le Chatelier’s Principle?
When a chemical system at equilibrium is disrupted by a change in a property, the system adjusts in a way to oppose the change. A new equilibrium is established, in which concentrations are different from their original value.
What is an application of Le Chatelier’s Principle?
Chemical engineers strive to design processes where reactants are continuously added and products are continuously removed, so that the equilibrium is never allowed to establish. If the reaction is always moving forward, the process is always making more products.
How does collision theory relate to concentration changes?
more reactant is added, the concentration of reactant molecules per unit volume increases, collisions are more frequent/successful for the forward reaction (rate increases)
How does temperature change relate to Le Chatelier’s Principle?
- the equilibrium shifts to minimize the temperature change
- If the system is cooled, the system tries to warm itself and the equilibrium shifts in the direction to produce more heat
- If heat is added, the equilibrium shifts in the direction that absorbs heat (cooling).
How does gas volume change relate to Le Chatelier’s Principle?
- total number of gas reactants and the total number of gas products need to be considered.
- Le Chatelier’s principle suggests that the system will react in way to resist the change by shifting to a side with more or less mols to change pressue
How does collision theory relate to gas volume changes?
When the volume of the reaction vessel decreases, the concentration of each gas in the mixture increases = more collisions occurring in the forward reaction
What changes do not affect the position of equilibrium?
- Adding catalyst: only decreases amount of time to reach equilibrium (lowers Ea for forward and reverse reactions) (NO OTHER AFFECTS)
- Adding inert gases: they are nonreactive (noble gases) only used to change pressure of system and redirect particle movement
What is solubility?
the amount of solute dissolved in a given amount of solvent to create a solution
What is Arrhenius Theory of Acids and Bases?
- When acids and bases dissolve in water, they dissociate into their ions
- acids dissociates to produce hydrogen ions
- base dissociates to produce hydroxide ions
