[asaaal]

more exothermic in a neautralisation reaction ? such as CH3COOH, it says because its a weak acid and its O-H bonds have to break for it to release H+. But that happens for all acids (as they are proton donors) so why is it more endothermic for a strong acid?

thanks in advance.

[jadomcp]

because the amount of energy required to break those bonds is less, but the energy released is the same, so therefore, the net release of energy is higher. (I think you mean weak at the end of your question, no?)

[asaaal]

(Original post by jadomcp)
because the amount of energy required to break those bonds is less, but the energy released is the same, so therefore, the net release of energy is higher. (I think you mean weak at the end of your question, no?)

but what makes weak acids bonding stronger? is that why they dont fully dissociate?
yeasss i was going to write more endothermic, but i just woke up and need about 3 hours to not feel like a zombie ;p

[jadomcp]

Sorry, my bad, I don't think my first statement makes complete sense, I do edexcel, so this isn't on my syllabus, so just sort of working it out, but basically, in a neutralisation reaction, you are displacing the positive ion in the alkali with an H+ ion, so this bonds with the OH- ion to form water whilst also forming a salt (from the negative ion that was in the acid and the positive ion that was in the alkali). This means that you have to break the bonds in in the acid, which requires energy, so a weak acid because it has weak bonds (contrary to what I said earlier I know, but this is right I promise!!), requires little energy to break up, so little energy is used in that. However, the bond it makes with the positive ion (to form water) is the same as it would be with a strong acid, so the energy released from that (making bonds is exothermic) is the same as it would otherwise be, so therefore, you have the same amount of energy being given out as by a strong acid, but less being used up, because the bonds are weaker. Therefore, there is less net energy usage, making it more exothermic. Sorry for the earlier confusion... Ahaha fair enough, I'm with you on that one! Morning exams are a nightmare! Hope that actually does help!

[jadomcp]

(Original post by asaaal)
but what makes weak acids bonding stronger? is that why they dont fully dissociate?
yeasss i was going to write more endothermic, but i just woke up and need about 3 hours to not feel like a zombie ;p

reply posted above, just realised that I forgot to quote you, sorry

[asaaal]

(Original post by jadomcp)
Sorry, my bad, I don't think my first statement makes complete sense, I do edexcel, so this isn't on my syllabus, so just sort of working it out, but basically, in a neutralisation reaction, you are displacing the positive ion in the alkali with an H+ ion, so this bonds with the OH- ion to form water whilst also forming a salt (from the negative ion that was in the acid and the positive ion that was in the alkali). This means that you have to break the bonds in in the acid, which requires energy, so a weak acid because it has weak bonds (contrary to what I said earlier I know, but this is right I promise!!), requires little energy to break up, so little energy is used in that. However, the bond it makes with the positive ion (to form water) is the same as it would be with a strong acid, so the energy released from that (making bonds is exothermic) is the same as it would otherwise be, so therefore, you have the same amount of energy being given out as by a strong acid, but less being used up, because the bonds are weaker. Therefore, there is less net energy usage, making it more exothermic. Sorry for the earlier confusion... Ahaha fair enough, I'm with you on that one! Morning exams are a nightmare! Hope that actually does help!

but wouldnt that make it more endothermic ?
because less energy is needed to break bonds so its less endothermic
but the same energy is given out when making bonds so both weak and strong acid are equally exothermic.
overall making it more endothermic :/