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# Water, water, water watch

1. I am having trouble with this annoying question. It hurt my head in the exam and I still can't figure out the answer to this:

Note: I think that the dissociation of water is exothermic (I've read this online).
2. (Original post by Doughboy)
I am having trouble with this annoying question. It hurt my head in the exam and I still can't figure out the answer to this:

Note: I think that the dissociation of water is exothermic (I've read this online).
What does water dissociate into? it is into hydrogen and oxygen(from which it is formed).

You are breaking bonds, it need energy, obviously it is endothermic, not exothermic. Think of electrolysis of water, why use electricity to split up water into its two constituents, it is because the dissociation of water is ENDOTHERMIC!
3. endothermic as has been said.

so you know it's endothermic, and now you need to know the difference between hydrogen ion levels in Alkalis & Acids.

Do acids have higher or lower?

then you should find the correct answer.

its a fairly easy question which just needs simple reasoning & common sense tbh - hence the 1 mark.
4. We'd be in a hell of a lot of trouble if the breaking of water bonds was exothermic...
5. (Original post by Kyle_S-C)
We'd be in a hell of a lot of trouble if the breaking of water bonds was exothermic...

Haha true.
6. the auto-ionisation of water is ENDOTHERMIC as energy as absorbed during bond breaking. It absorbs energy to form H30+ and OH- ions.

Check the equation for the acid disassociation constant. assume that water is a weak acid. [A-] = [OH-]. As temperature increases [H+] increases. As[H] = [A-] for a weak acid,the acid disassociation constant increases at a higher temperature. rearrange the equation to find [H+] and check -log [H+]
7. Okay. Thanks everyone!

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