Unit 3 Part 3 - equilibrium

Question 1

what is equilibrium?

Answer 1

a balance point reached in a reversible reaction if the conditions are not altered

Question 2

what happens at equilibrium?

Answer 2

the reactants change into products at exactly the same rate which the products change back into reactants

Question 3

what happens to the concentration of products and reactants at equilibrium?

Answer 3

they remain constant but not equal (this can only happen in a closed system)

Question 4

what is meant by the position of equilibrium?

Answer 4

the extent to which the reaction has taken place

Question 5

what, on a graph, indicates that the reaction has reached equilibrium?

Answer 5

the curve leveling out

Question 6

how can the position of equilibrium be altered?

Answer 6

when the reaction conditions are changed if an equilibrium has been established

Question 7

how will an increase in products affect equilibrium?

Answer 7

shifts to the right

Question 8

how will an increase in reactants affect equilibrium?

Answer 8

shifts to the left

Question 9

what is la chatelier’s principle?

Answer 9

if a system at equilibrium is subject to a change, the position of equilibrium will move to oppose the change

Question 10

how will increasing temp affect a reaction?

Answer 10

favours the endothermic reaction

Question 11

how will decreasing temp affect a reaction?

Answer 11

favours the exothermic reaction

Question 12

what is pressure a result of?

Answer 12

gas molecules bombarding the walls of the vessel in which the gas is contained

Question 13

the …… the number of moles in a given volume, the …… the pressure

Answer 13

greater

Question 14

how does increasing pressure affect the position of equilibrium?

Answer 14

position of equilibrium moves to the side with less moles of gas to decrease the pressure

Question 15

how does decreasing pressure affect the position of equilibrium?

Answer 15

position of equilibrium moves to the side with more moles of gas to increase the pressure

Question 16

give two rules about pressure in regards to the position of equilibrium?

Answer 16

pressure only affects the equilibrium of a system that involves gases + a pressure change will alter equilibrium only if there are different numbers of moles of gases on each side

Question 17

describe the effect on the equilibrium of adding a catalyst

Answer 17

rates of both the forward and backward reaction will be increase + a decrease in activation energy, so a catalyst does not alter the position of equilibrium but speeds up the rate at which equilibrium is attained

Question 18

how can the yield of ammonia be increased in the Haber process?

Answer 18

reaction conditions can be altered to increase the rate of the forward reaction to increase the yield of ammonia

Question 19

how do changes in concentration contribute to increasing the yield of ammonia?

Answer 19

• ammonia gas is cooled and liquid ammonia is piped off in a condenser; constantyl removing the ammonia gas decreases the rate of the backward reaction
• unreacted hydrogen and nitrogen are recycled; the increase in the concentration of the reactant gases increases the rate of the forward reaction

Question 20

how do changes in pressure contribute to increasing the yield of ammonia?

Answer 20

increasing pressure increases the rate of the forward reaction
the equilibrium shifts to the right because there are fewer moles of gas on the right - more ammonia would be produced

Question 21

how do changes in temp contribute to increasing the yield of ammonia?

Answer 21

the reaction is exothermic so a drop in temp would cause the reaction to shift to the right; more ammonia would be produced

Question 22

describe the effect of the catalyst used in the Haber process

Answer 22

iron catalyst

does not affect the position of equilibrium but allows the process to be carried out more efficiently at a lower temp

Question 23

Maximum yield of ammonia in the Haber Process requires ………… pressure and ……….. temperature. The process is made cost-effective using ………….atmospheres, ……………°C and a……….. , giving about ……………… % yield. The ammonia produced is ……………….out and the unreacted gases are ……………

Answer 23

high, low, 200, 400, catalyst, 15, condensed, recycled