Equilibrium and Yield

Question 1

Forward Reaction

Answer 1

Reactants on the Left - Products on right

Question 2

Back Reaction

Answer 2

Products react to form original reactants - reversible.

Question 3

Equilibrium

Answer 3

Dynamic (opposed to static) becuase, at equilibrium position, the forward and back reactions are still occurring, but at equal rates.

Prior to equilibrium - the rate of forward reaction EXCEEDS the rate of back reaction.

At Equili - forward equals back

• Products and reactants eventually reach constant values.

Question 4

Difference between Rate and Yield:

Answer 4

Rate - how fast

Yield - how much

Question 5

Concentration time graphs

Answer 5

Reactant: product ratio is 1:1.

*If not the curves on the graph will not be symmetrical.

Question 6

Equilibrium Constant

Answer 6

describes the yield of the products relative to the quantities of the reactants.

Question 7

Large Kc value greater than 10 indicate

Answer 7

• A high yield of products at the equilibrium position.

- the reaction has proceeded to a large extent to the right by the time the equilibrium position is reached.

Question 8

Small Kc values less than 0.1 indicate:

Answer 8

• A low yield of products at the position.

- the reaction has proceeded to a small extent to the right by the time the equilibrium position is reached.

Question 9

Changes in Concentration: Reactants

Answer 9

Increase of reactant = shift equilibrium to the right (in the direction of consumption of the reactant)

Decrease of reactant = shift equilibrium to the left (in the direction of formation of the reactant)

Question 10

Changes in Concentration: Products

Answer 10

Increase = shift equilibrium to the left (in the direction of product consumption) * favours back reaction

Decrease = shift equilibrium to the right (in the direction of product formation).

Question 11

Pressure

Answer 11

Increase pressure - decrease volume of the vessel = equilibrium shifted to produce a smaller number of molecules in the gas phase.

Question 12

Temperature

Answer 12

If forward reaction of an equilibrium system is exothermic = back reaction endothermic to the same mag.

Question 13

Temperature Increase/decrease

Answer 13

Shifts in the direction that absorbs heat from surroundings. *Shifted to endothermic direction.

Decrease - direction that releases heat. Shift exothermic direction.

Question 14

Catalyst

Answer 14

Will speed up both forward and back - no uneven shift in either direction at equili.

*Just help reach the point sooner.