[INeedSerotonin]

The following graph represents N₂ + O₂ <------> 2 NO



Which of the following propositions are true?

I) in the combustion chamber, the formation of NO is more efficient than in the exhaustion system.

II) the formation reaction of NO is exothermic;

III) lowering the temperature favors the decomposition of NO into N₂ and O₂.

Answer: (I) and (III)

Could you guys give me a hint here? I think that (I) is true because Kc = products / reagents, so the greater is the Kc, the greater is the quantity of products. This also helps me find that (III) is true. But what about (II)?

Thanks

[mjc123]

Do you know an equation that describes how the equilibrium constant changes with temperature?
If not, are you familiar with Le Chatelier's principle? How would the equilibrium shift with temperature in an exothermic reaction?

[INeedSerotonin]

Do you know an equation that describes how the equilibrium constant changes with temperature?
If not, are you familiar with Le Chatelier's principle? How would the equilibrium shift with temperature in an exothermic reaction?

Unfortunately, I don't know that equation, but I'm familiar with the Le Chatelier's principle. I think that, in an exothermic reaction, when we raise the temperature, the equilibrium should shift to the reagents. However, this is not what happens, because we are raising the temperature and Kc is getting bigger and bigger, which means the equilibrium is shifting torwards the products.

Is this correct?

[mjc123]

Correct.
Look up "van't Hoff equation".

[INeedSerotonin]

Correct.
Look up "van't Hoff equation".

Thank you! I will!