This is an exercise in Le Chatelier's Principle. That principle says that a system in equilibrium will shift (that is it will move to the left or to the right) when we do something to it. The shift will be such that it will try to undo what we did to it. I'll do the backbone for you and let you do the rest of the work. Note that dH is +. That merans the reaction, just to clarify a little, i this.
2NH3 + heat ==> N2 + 3H2
So question 1 wants to know about decreasing temperature. So we ask ourselves which way will the rxn shift if we remove heat. If we take heat away the rxn will shift so as to ADD heat back. Let's look at what might happen. If the rxn shifts to the right it USES heat; if the rxn shifts to the left it ADDS heat. If we are taking it away, then the rxn will shift to the left. That means that everything on the left will get larger (the reactant side) and everything on the right (the product side) will get smaller. That is the underlying principle that will allow you to answer all of the questions. I will be glad to check your answers if you show them ALONG WITH THE REASON YOU CHOSE THAT ANSWER.
refer to the reaction 2NH3 (g) ↔ N2 (g) + 3H2 (g), and ΔH = 92.2 kJ.
1.What will be the effect on the concentration of H2 if the temperature decreases?
A. H2 concentration will decrease.
B. H2 concentration will not change.
C. H2 concentration will increase.
D. H2 concentration will not change, but ΔH will decrease.
E. H2 concentration will not change, but pressure will increase.
2. What will be the effect on the concentration of NH3 if the pressure decreases?
A. NH3 concentration will decrease.
B. NH3 concentration will not change.
C. NH3 concentration will increase.
D. NH3 concentration will not change, but ΔH will decrease.
E. NH3 concentration will not change, but entropy will increase.
3. What will be the effect on N2 if the concentration of NH3 increases? _______
A. N2 concentration will decrease.
B. N2 concentration will not change.
C. N2 concentration will increase.
D. N2 concentration will not change, but ΔH will decrease.
E. N2 concentration will not change, but pressure will increase.
1 answer
1 answer