Equilibria

Question 1

What happens when a reversible reaction reaches equilibrium?

Answer 1

The rate of forward and reverse reactions are equal

Question 2

Write an expression for Kc for the following reaction:
2A + B –> C + 3D

Answer 2

[C] x [D]^3 / [A]^2 x [B]

Question 3

Define the term dynamic equilibrium

Answer 3

When a reversible reaction is in a closed system, the rate of the forward and reverse reactions are the same, and remain at a constant rate

Question 4

What factor affects the value of Kc ?

Answer 4

temperature only

Question 5

What information shows if a reaction is exothermic or endothermic?

Answer 5

Reactions at equilibrium are shown with a value for H for the forward direction
- H indicates forward reaction is exothermic (and therefore reverse is endothermic)
+ H icates forward reaction is endothermic (and therefore reverse is exothermic)

Question 6

What is Le Chatelier principle?

Answer 6

For a reversible reaction in dynamic eqm, if a change is imposed in the system, the eqm will shift to oppose the change

Question 7

What happens to the position of an equilibrium if pressure is increased?

Answer 7

The equilibrium shifts to the side of the reaction with less number of gaseous moles

Question 8

What happens to the position of an equilibrium if temperature is increased?

Answer 8

The equilibrium shift to the endothermic direction to reduce temperature

Question 9

What happens to the position of an equilibrium if the concentration of a reactant is increased?

Answer 9

The equilibrium shifts to the products to remove the added reactants

Question 10

How does the addition of a catalyst affect a reaction at
equilibrium?

Answer 10

Does not affect the position of equilibrium, but speeds up the rate at which equilibrium is achieved

Question 11

Why does a catalyst not impact the yield?

Answer 11

increases the rate of forwards and reverse reactions equally