chapter six_chemical equilibria

Question 1

definition of:
reversible reactions
dynamic equilibrium

Answer 1

rr: when the backward and forward reactions happen simultaneously, where a mixture of products and reactants are obtained
de: when the rate of the forward reaction equals the rate of the backward reaction. It must be achieved in a CLOSED SYSTEM.

Question 2

LCP: effects of pressure

Answer 2

1. for GASES ONLY: changes in pressure in a CLOSED SYSTEM
   the increase in pressure decreases the volume, the POE shifts to favour the side which has less number of moles, this then DECREASES THE PRESSURE and increase volume, and increases the production of gases on the side with less moles of gases

Question 3

LCP: effects of temperature

Answer 3

2. effect of temperature:
   an increase in temperature will the POE to shift to the side favouring the endothermic process so as to decrease the temperature. Hence the production of reactants/products on that side of the equilibrium is increased.

Question 4

LCP: effects of the presence of a catalyst

Answer 4

3. effects of the presence of the catalyst
   THIS DOES NOT AFFECT POE, IT ONLY AFFECTS ROR
   it increases the rate of BOTH FORWARD AND BACKWARD REACTIONS, because it LOWERS THE AE of BOTH REACTIONS BY THE SAME EXTENT.

Question 5

Haber Process requirements

Answer 5

450c 250 atm finely divided iron catalyst

forward reaction is exothermic

Question 6

State the equilibrium law

Answer 6

the equilibrium law states that if a reversible reaction is allowed to reach an equilibrium, [product]x[product] / [reactant]x[reactant] =k, which is the equilibrium constant

Kc represents ROR, not POE. It is also only affected by TEMPERATURE, and is unaffected by catalysts and pressures.

Qc(reaction quotient) is the instantaneous concentration, and when Kc=Qc, the equilibrium has been reached