A friend of mine stumbled upon this question while revising equilibrium. Apparently the answer is A.

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The answer obviously cannot include adding a catalyst. Furthermore, according to le Chatelier's principle, as temperature increases, the side with the endothermic reaction is favoured, in this case 2NO(g). Also, if there is an increase in pressure, the side with fewer moles of gas will be favoured as it consumes more moles of gas. However, as both sides of the reaction have an equal amount of moles of gas, I would believe this to not have any effect and thus answer C. Hence, how come the answer is A?

  • 4
    $\begingroup$ By mistake, that's how. Your reasoning is fine. $\endgroup$ Jun 20, 2019 at 16:59
  • $\begingroup$ You cannot apply Le Châtelier's principle to temperature. The effect is correct, but the reasoning is wrong. chemistry.stackexchange.com/questions/62852/… $\endgroup$
    – Zhe
    Jun 20, 2019 at 17:47
  • $\begingroup$ @Zhe I stated that as temperature increases, the side with the endothermic reaction is favoured. I did not provide any reasoning for this. $\endgroup$
    – Liam
    Jun 20, 2019 at 18:09
  • 1
    $\begingroup$ It is really disappointing how many exam papers contain errors. $\endgroup$
    – porphyrin
    Jun 20, 2019 at 18:13
  • $\begingroup$ Application of the Le Châtelier's Principle for a temperature effect is evidence of the incorrect reasoning. It gives the correct answer but for the wrong reason. $\endgroup$
    – Zhe
    Jun 20, 2019 at 18:35


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