Chemical equilibrium Flashcards
When the reaction quotient is large than the equilibrium constant
𝑄c > 𝐾c: The ratio of initial concentrations of products to reactants is too large. To reach equilibrium, products must be converted to reactants. (consuming products, forming reactants)
Reaction will proceed in the reverse direction
When the reaction quotient is equal to the equilibrium constant
The initial concentrations are equilibrium concentrations. The system
is at equilibrium.
When the reaction quotient is small than the equilibrium constant
𝑄c < 𝐾c
The ratio of initial concentrations of products to reactants is too small.
To reach equilibrium, reactants must be converted to products. The system proceeds from left to right (consuming reactants, forming products)
Reaction will proceed in the forward direction
Le Chātelier’s principle
Change in any of the factors that determine the equilibrium conditions of a system will cause the system to change in such a manner so as to reduce or to counteract the effect of the change.
This is applicable to all physical and chemical equilibria.
Heterogenous equilibrium
Equilibrium in a system having more than 1 phase is called heterogenous equilibrium.
Effect of pure solids, pure liquids and solvents on equilibrium constants
The concentrations of pure solids, pure liquids and solvents are emitted from equilibrium constant expression. (Does not change significantly)
Effect of catalysts on equilibrium
Equilibrium position of an equilibrium reaction cannot be changed by adding a catalyst
They increase the rate of forward and backward reaction to the same extent.
Arrhenius concept of acids and bases
acids are substances that dissociates in water to give hydrogen ions H+(aq) and bases are substances that produce hydroxyl ions OH–(aq)
The Brönsted -Lowry definition of acids and bases
acid is a substance that is capable of donating a hydrogen ion H+ and bases are substances capable of accepting a hydrogen ion, H+
How to derive conjugate acids and bases from compounds
The conjugate bases should have one proton less while a conjugate acid should have one extra proton
Effects of neutralisation of strong acids an bases and weak acids and bases
Strong acids and bases simply gets hydrated but not hydrolysed, due to this their pH remains neutral at 7.
Effect of the presence of the ion in the ionisation of an acid
The presence of a common ion suppresses the ionisation of a weak acid
How to predict if a precipitate will be formed or not in a solution
Determined by the ionic product
If IP=Ksp (solution is saturated but no precipitate will be formed)
IP > Ksp (precipitate will be formed)
IP < Ksp (solution is not saturated and no ppt will be formed)
Factors affecting solubility
Presence or absence of a common ion
Ph
What physical property should be kept constant to keep Ka and Kb constant
Temperature
When a solution containing a weak acid is diluted, its pH
Concentration of H3O+ reduces, increasing the pH value (solution becomes less acidic)
When a solution containing a weak base is diluted, its pH
Concentration of OH- reduces, so pH decrease (solution becomes less basic)
What happens when a titration mixture at the equivalence point containing strong base and weak acid is diluted
Titration mixture at the equivalence point will be weakly basic
So when its diluted concentration of OH- reduced, pH decreases
When a solution containing a buffer solution is diluted, its pH
pH remain constant
How does the presence of a common ion affect the molar solubility of a compound
Molar solubility decreases in the presence of a common ion
Dalton’s law
Total pressure is the sum of partial pressures of components in the system
Properties of the component having higher partial pressure in a system
Will have high volatility or high concentration
Relationship between the vapour pressure of a component with its boiling point
If a certain compound has higher vapour pressure, that means that the inter-molecular forces between the that particular component should be relatively weak. Hence it will need relatively lower energy to break the bonds between its molecules. ( components having higher vapour pressure will have lower boiling points)
