reversible reactions

Question 1

reversible reaction

Answer 1

the products can react to form the reactants

Question 2

how can the direction of a reaction be changed?

Answer 2

by changing the conditions

Question 3

exo v endo rule

Answer 3

• if the forward reaction is exothermic, the backward reaction will be endothermic vice versa
• same amount of energy is transferred in each case

Question 4

copper sulfate equation and colour forward

Answer 4

hydrated copper sulfate (blue) ⇌ anhydrous copper sulfate (white) + water

Question 5

forward direction copper sulfate+ why + energy transfer

Answer 5

endothermic, temp decrease, taken in from the surroundings

Question 6

reverse direction copper sulfate+ why + energy transfer

Answer 6

exothermic, temp increase, transferred to surroundings

Question 7

ammonium chloride example

Answer 7

ammonium chloride ⇌ ammonia + hydrogen chloride
heat forward, cool backwards

Question 8

dynamic equilibrium

Answer 8

• the rate of the forward reaction = the rate of the reverse reaction
• both reactants and products are constantly turning into each other
• must take place in closed system as a reversible reaction
• quantities of reactants and products do not change so reaction appears to have stopped, no observable changes

Question 9

equilibrium

Answer 9

reached when the forward and reverse reactions occur at exactly the same rate

Question 10

state le chatelier’s principle

Answer 10

if a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change

Question 11

concentration

Answer 11

• if the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again
• if the concentration of a reactant is increased, more products will be formed until equilibrium is reached again
• if the concentration of a product is decreased, more reactants will react until equilibrium is reached again

Question 12

temp increase

Answer 12

• the relative amount of products at equilibrium increases for an endothermic reaction
• the relative amount of products at equilibrium decreases for an exothermic reaction.

Question 13

temp decrease

Answer 13

• the relative amount of products at equilibrium decreases for an endothermic reaction
• the relative amount of products at equilibrium increases for an exothermic reaction

Question 14

pressure

Answer 14

• an increase in pressure causes the equilibrium position to
  shift towards the side with the smaller number of molecules
• a decrease in pressure causes the equilibrium position to shift
  towards the side with the larger number of molecules