Chemical equilibrium

Question 1

When the reaction quotient is large than the equilibrium constant

Answer 1

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

Question 2

When the reaction quotient is equal to the equilibrium constant

Answer 2

The initial concentrations are equilibrium concentrations. The system
is at equilibrium.

Question 3

When the reaction quotient is small than the equilibrium constant

Answer 3

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

Question 4

Le Chātelier’s principle

Answer 4

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.

Question 5

Heterogenous equilibrium

Answer 5

Equilibrium in a system having more than 1 phase is called heterogenous equilibrium.

Question 6

Effect of pure solids, pure liquids and solvents on equilibrium constants

Answer 6

The concentrations of pure solids, pure liquids and solvents are emitted from equilibrium constant expression. (Does not change significantly)

Question 7

Effect of catalysts on equilibrium

Answer 7

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.

Question 8

Arrhenius concept of acids and bases

Answer 8

acids are substances that dissociates in water to give hydrogen ions H+(aq) and bases are substances that produce hydroxyl ions OH–(aq)

Question 9

The Brönsted -Lowry definition of acids and bases

Answer 9

acid is a substance that is capable of donating a hydrogen ion H+ and bases are substances capable of accepting a hydrogen ion, H+

Question 9

How to derive conjugate acids and bases from compounds

Answer 9

The conjugate bases should have one proton less while a conjugate acid should have one extra proton

Question 10

Effects of neutralisation of strong acids an bases and weak acids and bases

Answer 10

Strong acids and bases simply gets hydrated but not hydrolysed, due to this their pH remains neutral at 7.

Question 11

Effect of the presence of the ion in the ionisation of an acid

Answer 11

The presence of a common ion suppresses the ionisation of a weak acid

Question 12

How to predict if a precipitate will be formed or not in a solution

Answer 12

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)

Question 13

Factors affecting solubility

Answer 13

Presence or absence of a common ion
Ph

Question 14

What physical property should be kept constant to keep Ka and Kb constant

Answer 14

Temperature

Question 15

When a solution containing a weak acid is diluted, its pH

Answer 15

Concentration of H3O+ reduces, increasing the pH value (solution becomes less acidic)

Question 16

When a solution containing a weak base is diluted, its pH

Answer 16

Concentration of OH- reduces, so pH decrease (solution becomes less basic)

Question 17

What happens when a titration mixture at the equivalence point containing strong base and weak acid is diluted

Answer 17

Titration mixture at the equivalence point will be weakly basic
So when its diluted concentration of OH- reduced, pH decreases

Question 18

When a solution containing a buffer solution is diluted, its pH

Answer 18

pH remain constant

Question 19

How does the presence of a common ion affect the molar solubility of a compound

Answer 19

Molar solubility decreases in the presence of a common ion

Question 20

Dalton’s law

Answer 20

Total pressure is the sum of partial pressures of components in the system

Question 21

Properties of the component having higher partial pressure in a system

Answer 21

Will have high volatility or high concentration

Question 22

Relationship between the vapour pressure of a component with its boiling point

Answer 22

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)