Question

Consider the reaction:

2 CO_2(g) + Heat = 2 CO_(g) + O_2(g)

1.  Predict the effect on the equilibrium system if the reaction temperature is decreased. (You may wish to write the equilibrium constant expression for the reaction first).

a) The equilibrium will shift to the right favoring the products.

b) The equilibrium will shift to the side that the light side of the force is on.

c) There will be no effect.

d) The equilibrium will shift to the left favoring the reactants.

2. Looking at the same equilibrium system, predict the effect if the CO2 gas concentration is increased.

a) The equilibrium will shift to the right favoring the products.  

b) There will be no effect.

c) There will be a Tyndall effect.

d) The equilibrium will shift to the left favoring the reactants.

3. Referencing the same equilibrium system as in Questions 1 and 2, how would the relative amounts of O2 and CO2 change after the removal of some CO gas from the equilibrium reaction?

a) The relative amount of carbon dioxide would decrease and the relative amount of oxygen would decrease.

b) The relative amount of carbon dioxide would increase and the relative amount of oxygen would increase.

c) The relative amount of carbon dioxide would increase and the relative amount of oxygen will decrease.

d) The relative amount of carbon dioxide would decrease and the relative amount of oxygen would increase.

3. Consider this system at equilibrium: (Brown) 2 NO_2(g) = N₂O_4(g) (Colorless). Predict the color of the reaction mixture at -15 degrees Celsius.

a) Purple  

b) Aqua  

c) Colorless  

d) Brown

Answer 1

This can be explained based on lechatliers principle

The principle says that if a change in pressure, temperature, or concentration of a reactant is applied to a system in equilibrium, the equilibrium will shift so as to tend to counteract or nullify the effect of the change.

So, equilibrium constant for 2CO₂+ Heat <----> 2CO + O₂

K = [CO]²[O₂]/[CO₂]²

1A) Option D.

Decrease in temperature equilibrium constant decreases so K value decreases means denominator value increases i.e., CO₂ amount increases means reaction shifts favouring reactants

2A) Option A

CO2 concentration increased represents increase in concentration of rectants and according to lechatliers principle the system counteract the change by decreasing the amount of reactants i.e., more reactants converts to products favours farward direction

3A) Option D

CO removal means the one of the product removed then equilibrium will counteract in such a way that more reactant convert into products i.e., decreace in CO₂ and increase in O₂ is observed

4A) Option C

2NO₂ <----> N₂O₄ (NO₂= brown ; N₂O₄ =colour less)

At -15degree celcius kinetic energy of gas molcules lowered, NO₂ molecules will come nearer to eachother and they combine forming N₂O₄ so at -15degree celcius the reaction mixture sems colourless