In: Chemistry
Consider the following reaction at equilibrium.
2H2O (g) + 2SO2 (g) <--> 2H2S (g) + 3O2 (g)
What effect will adding more H2S have on the system?
A) The reaction will shift in the direction of reactants
B) The equilibrium constant will increase
C) The reaction will shift in the direction of products
D) The equilibrium constant will decrease
E) No change will be observed
Can you explain why the one that is the right answer correct and along with also explaining why the others are wrong?
The right answer is: A) The reaction will shift in the direction of reactants
The reaction equilibrium follows the Le Chatelier's principle as "When any system at equilibrium is subjected to change in concentration, temperature, volume, or pressure, then the system readjusts itself to (partially) counteract the effect of the applied change and a new equilibrium is established."
So, adding more gaseous H2S in system will force equilibrium to move towards reactant side as this side number of moles of gaseous species are less (2+2 = 4) than product side (2+3 = 5) to avoid any pressure from product side.
(B) The equilibrium constant will not change ( because it is independent of the analytical concentrations of the reactant and product species in a mixture. It only depends on temperature and on ionic strength).
(C) As explained above reaction will not shift in the direction of products.
(D) No change in equilibrium constant (as above explained)
(E) Change will be observed du to above factors.