Urgent, really urgent chemistry help on reactions in needed here.?

Question

Which of the following reactions will favour the formation of products, when the temperature is raised by 10ºC and reaction is carried out in a closed container?

(Reaction 1) N2 + 3H2 <-----> 2NH3 + 92 KJ
(Reaction 2) 2Cl2 + 2H2O <-----> 2HCl + O2 - 113KJ

<-----> stands for reversible reaction. 'KJ' means kilojoules.

I think it is the reaction of chlorine with water, but I must explain why.

Answer 1

Le Chatelier's principle says that the equilibrium will shift to eliminate the stress.
The endothermic reaction (negative dH) will favour products when temp is increased.
I think that reaction two is your answer

Answer 2

Your ans is right. Based on Le Chatelier's principle, an increase in temperature in an endothermic reaction will shift the reaction right. And also due to the fact that the reaction is carried out in an enclosed container (which means constant volume), the reaction will shift left since there are only 3 moles of products which is lesser than the 4 moles of reactants. This effect is similar to the increase in pressure.

Answer 3

*Reaction 2.

Le Chatelier's principle states that the system will try to counteract an increase in temperature by decreasing it. Hence the reaction which takes in heat (endothermic) will be increased.

So in reaction one, since the enthalpy of reaction is positive, the forward reaction is exothermic, meaning increasing the temperature will increase the amount of reactants produced (as the backward reaction is exothermic).

In reaction 2, the negative enthalpy value indicates that the forward reaction is endothermic, hence an increase in temperature will favour the forward reaction and form more products.

*(Are you sure reaction 1's enthalpy value is correct? According to Wikipedia it should be -92KJ?)

Answer 4

Molecular nitrogen (N2) in the atmosphere is relatively non-reactive due to its strong bond, and N2 plays an inert role in the human body, being neither produced or destroyed. In nature, nitrogen is slowly converted into biologically (and industrially) useful compounds by some living organisms, notably certain bacteria (i.e. nitrogen fixing bacteria - see Biological role above). Molecular nitrogen is also released into the atmosphere in the process of decay, in dead plant and animal tissues. The ability to combine or fix molecular nitrogen is a key feature of modern industrial chemistry, where nitrogen and natural gas are converted into ammonia via the Haber process. Ammonia, in turn, can be used directly (primarily as a fertilizer, and in the synthesis of nitrated fertilizers), or as a precursor of many other important materials including explosives, largely via the production of nitric acid by the Ostwald process.

But the chlorine is very reactive, extremely and dangerous. then the explanation is: N2 is not reactive, but Cl2 is extremely reactive.

Answer 5

The secret is the entropy. Entropy is higher on the side of the reaction that has more moles of gas. That's the left in the first reaction, and it's not clear in the second reaction because we don't know if H2O is a liquid or a gas there. Higher temperature favors disorder. So when you raise the temperature in the first reaction, you're favoring the left side. In the second reaction, if H2O is a liquid, then higher temperature favors the right side.

Answer 6

Le Chateliers principle is the answer. Treat the extra energy as an excess reactant. which way will equilibrium shift to use the excess? You're right about the answer though.

Answer 7

excellent answer crazygirl.. I couldn't have written it better myself.... oh wait.. I did write it! Glad to see you read it and liked it. :)