r2.3 extent of chemical change

Question 1

what is physical equilibrium?

Answer 1

physical equilibrium involves a change of state such as evaporation or condensation. a liquid in equilibrium with its own vapour is a physical equilibrium example as there is no change in chemical identity. this is also called a phase equilibrium as the particles are changing between phases

Question 2

what is an example of physical equilibirum?

Answer 2

an example is a sealed flask containing water. the processes of evaporation and condensation are still occurring in this closed system - on a macroscopic level, there is no change in the level of the liquid. at equilibrium, the rate of evaporation is equal to the rate of condensation

Question 3

how does a saturated solution establish equilibrium?

Answer 3

a saturated solution in a closed system will also establish dynamic equilibrium if there is excess solid present. the shape of the crystals may change but the amount of saturation will remain constant

Question 4

what is chemical equilibrium?

Answer 4

a chemical system is in dynamic equilibrium when:
- the concs of the reactants and products remain constant
- the rate of the forward reaction is the same as the reverse reaction
- this can only occur in a closed chemical system

Question 5

when does the equilibrium lie to the left?

Answer 5

if the concentration of reactants is greater than that of products at equilibrium, the equilibrium is said to lie towards the reactant (left)

Question 6

when does the equilibrium lie to the right?

Answer 6

if the concentration of products is greater than that of reactants at equilibrium, the equilibrium is said to lie towards the product (right)

Question 7

what is Kc?

Answer 7

the equilibrium constant, Kc, of a reaction is a ratio that provides information about the composition of a reaction mixture at equilibrium. it is only affected by a change in temperature
- it gives information about the extent of the reaction