5J.9

[ayushibanerjee06]

Consider the equilibrium 3 NH3(g) + 5 O2(g) <-> 4 NO(g) + 6 H2O(g). (a) What happens to the partial pressure of NH3 when the partial pressure of NO is increased? (b) Does the partial pressure of O2 decrease when the partial pressure of NH3 is decreased?
Can someone explain why both NH3 and O2 increase? I don't get why

[Rachel Yu 1G]

Remember in lecture Dr. Lavelle said that increasing/decreasing pressure changes the concentration IF pressure is changed by volume. I think in this problem we assume that pressure is changed by volume. This means that an increase in the partial pressure of NO results in an increase in the concentration of NH3. Using Le Chatelier's Principle, we can find that an increase in concentration of NO will make the reaction reactant-favored. The same reasoning can be used to solve part B.

[Paul Hage 2G]

When the partial pressure of NO is increased (the concentration of NO increases because P=(conc)(RT)), the partial pressure (and thus concentration) of NH3 will increase because the reaction will shift towards the reactants to minimize the effect of the change.
When the partial pressure (and concentration) of NH3 is decreased, the reaction will shift towards the reactants. Therefore, the partial pressure of O2 will increase to minimize the effect of the change.
Both NH3 and O2 increase because the reaction shifts towards the reactants, increasing the amount of both reactants.

[DanielTalebzadehShoushtari2A]

I read it as adding more partial pressure of something means adding more moles of it. If you add more moles of NO, the amount of NH3 increases in order to restore equilibrium ratio of products to reactants. When NH3 is decreased, the reaction shifts so as to increase reactants (to restore equilibrium) and so O2 is increased.