[guitarch94]

Hi everyone,

I'm a little confused about how endothermic reactions are more affected by changes in temperature.

My notes say that:

"with an increase in temperature, equilibrium will shift in endothermic reaction. Reactions with more activation energy are more temperature dependent.(endothermic reactions are more temperature dependant"

I don't really understand my notes and why endo is more affected by temp change than exo. Is it because that reactions with higher temperatures have more molecules with threshold energy? I'm confused.

Edit: I understand "Le Chatelier's Principle" but I need a more "scientific" explanation.

[Organic_lover*]

Well, an endotermic reaction are more affected by the increase in temperature because it's reagents need to absorve energy to react together, right? If you put the reagents in contact, for example, the reaction occurs normally (you can "feel" it by the cooling of the system where this reaction occurs) but, if you give it more heat, they molecules will "get more quickly" the energy needed to react.

The exotermic reactions, due to the fact that they release energy to the system, are spontanious (there isn't the need of absorve energy to react).

To understand better, think in activation energy and remember the concepts of exo and endotermic reactions.

I hope to have helped you. Bye bye

[thetada]

Both exothermic and endothermic reactions require activation energy, that is, a little energetic push to get them started. The difference is that in exothermic reactions, the first set of reactants that react will produce energy and that energy can be used to provide the activation energy for the next set of reactants. Endothermic reactions need the initial activation energy but then the reagents absorb energy as they react. This in turn means that endothermic reactions are easier to stop - you can cool down the reaction vessel - whereas exothermic reactions once they get going are harder to stop, explosions being a notable example. This is why it's so easy to burn caramelised sugar because the reaction responsible is accelerated by the heat it produces. This greater degree of control we can exert on endothermic reactions could be considered as a sign of their greater sensitivity to temperature.

[XGen]

If you think about it in Le Chatelier's Principle, you have the general endothermic reaction:

A + B + heat -> C + D

If you consider heat as one of the reactants, extra heat means that the equilibrium will shift to the right, following Le Chatelier's Principle.

For a more "realistic" response, with activation energies and etc, look at the posts above. They sum it up nicely.