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    Hi

    Having studied chemistry to A2 level, I've met lots of things that can't be explained with a level of knowledge that I have at the moment. However lots of the time, energy arguments are resorted to such as 'it makes it more energetically stable' or 'it contains less energy' or 'benzene is more stable because of the delocalised pi cloud'.

    At higher level chemistry are these ideas explored more? It's annoying to hear people resort to energy arguments without any justification - why would a molecule 'want' less energy?

    Thanks

    l4ith
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    (Original post by l4ith)
    Hi

    Having studied chemistry to A2 level, I've met lots of things that can't be explained with a level of knowledge that I have at the moment. However lots of the time, energy arguments are resorted to such as 'it makes it more energetically stable' or 'it contains less energy' or 'benzene is more stable because of the delocalised pi cloud'.

    At higher level chemistry are these ideas explored more? It's annoying to hear people resort to energy arguments without any justification - why would a molecule 'want' less energy?

    Thanks

    l4ith
    It's good that you question things.

    There is no volition in inanimate objects (molecules and other such things), however it seems to be a universal 'fact' that systems move towards lower energy naturally.

    Think about a ball at the top of a hill - it will easily roll to the bottom quite spontaneously.

    Once you start to probe deeper into the reasons for this apparently one directional effect, the concept of entropy rears its ugly head. This is the real reason things 'happen' in the universe.

    Entropy can be thought of as the degree of disorder of a system. As the universe is sooo complex and the number of particles sooo fantastically large and the amount of available energy, which can reside on the particles of the universe sooooo incredibly large, the universe becomes governed by the laws of probablilty and statistics (as are we all).

    Entropy tells us that in the event of there being any two ways that something can occur, the one which is most likely will/has to happen. Not because of any other reason but that it's more likely and the probability is virtually infinitely weighed in favour of the likely reaction.

    We understand simple probablilties and realise that the odds of a casino losing at roulette over the course of a year is 'virtually' impossible. Well a roulette wheel has only 37 slots. The universe has an unthinkable number of particles and energy states - when the odds are weighed in the universe's favour it HAS to happen.

    So, to give it a chemical slant. Any process that results in an increase in universal entropy is favourable and providing the kinetics allow it to start, it WILL happen. (the kinetics means the activation energy barrier must be overcome).

    And to return to your original statements, benzene is said to be energetically more stable (of lower energy) because when it reacts it provides less entropy to the universe than a comparable system changing.

    To explain all of this every time we discuss a chemical change (or a physical one) is clearly a pain in the arse, so we accept that systems tend to move towards lower energy states (providing more entropy for the universe and being inevitable) because that's the way it is!

    At A2 you will study Gibbs free energy, which takes these ideas on board.
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    Wow thanks that's a great answer
 
 
 
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