7. Equilibrium

Question 1

reversible reactions

Answer 1

happen when the products of a reaction can react to form the reactants again
A + B <-> C + D

Question 2

what happens to rate and conc. at equilibrium

Answer 2

• the rate of the forwards and the backwards reaction are the same
• conc.s of the products and reactants remain constant

Question 3

what happens to a reaction in a closed system

Answer 3

in a closed system (nothing can get in or out) a reversible reaction will reach equilibrium.

Question 4

Le Chatelier’s Principle

Answer 4

A system (reaction) will oppose any change that is made.
A change could be:
- temperature
- concentration
- pressure

Question 5

equilibrium shifts (to the left and to the right)

Answer 5

to the left:
more reactants are made -> ‘shifting to the left in favour of the reactants’
to the right:
more product(s) will be made - ‘shifting to the right in favour of the products’

Question 6

homogeneous

Answer 6

when all the components of a mixture are in the same form e.g. air

Question 7

heterogeneous

Answer 7

when the components of a mixture are in different phases e.g. a mixture of sand and water

Question 8

phase

Answer 8

a physically distinctive form of matter

Question 9

dynamic equilibrium

Answer 9

when the rate of the forward and backwards reaction are the same. Concentrations of the reactant(s) and product(s) remain constant.

Question 10

heterogeneous catalyst

Answer 10

a catalyst in a different phase to the reactants