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Energy profile diagrams, Exothermic reactions! Watch

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    Referring to an energy profile diagram, in an exothermic reaction are reactants high in energy because they're more unstable?

    basically after revisiting AS chemistry i began to wonder if the reason why reactants had a higher energy in an energy-profile diagram is due to lots of potential energy stored in the bonds which made them relatively energetically unstable thus only needing a small amount of activation energy to break their unstable energized bonds to form energetically stable products with a lower bond energy.

    BASICALLY: what i want to know is: the reason why reactants are at a higher energy level in an exothermic reaction?
    do they have more potetnial energy stored in their bonds?

    if so does that mean theyre unstable? if thats the case then what makes them so unstable?

    feel like im getting really confused
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    (Original post by mercuryman)
    Referring to an energy profile diagram, in an exothermic reaction are reactants high in energy because they're more unstable?

    basically after revisiting AS chemistry i began to wonder if the reason why reactants had a higher energy in an energy-profile diagram is due to lots of potential energy stored in the bonds which made them relatively energetically unstable thus only needing a small amount of activation energy to break their unstable energized bonds to form energetically stable products with a lower bond energy.

    BASICALLY: what i want to know is: the reason why reactants are at a higher energy level in an exothermic reaction?
    do they have more potetnial energy stored in their bonds?

    if so does that mean theyre unstable? if thats the case then what makes them so unstable?

    feel like im getting really confused
    You are basically correct BUT the potential energy they have is the energy that COULD be released by breaking the bonds they have and making stronger ones.

    They are more unstable because they have WEAKER bonds overall.
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    (Original post by charco)
    You are basically correct BUT the potential energy they have is the energy that COULD be released by breaking the bonds they have and making stronger ones.

    They are more unstable because they have WEAKER bonds overall.
    First of all, THANK YOU SO MUCH FOR GETTING BACK!!

    anyways, ok so, after reading your statement, I decided to change my understanding of this.

    Heres what i now think:

    Reactants are at a high energy level because they have a lot of potential energy in their bonds that could be released by breaking THOSE bonds.

    However, reactants such as Methane and oxygen have weaker bonds than CO2 and H20, making them unstable?

    in short, reactants in an exothermic reaction like methane for instance, have weak bonds with high potential energy?

    Is this correct?
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    (Original post by mercuryman)
    First of all, THANK YOU SO MUCH FOR GETTING BACK!!

    anyways, ok so, after reading your statement, I decided to change my understanding of this.

    Heres what i now think:

    Reactants are at a high energy level because they have a lot of potential energy in their bonds that could be released by breaking THOSE bonds.

    However, reactants such as Methane and oxygen have weaker bonds than CO2 and H20, making them unstable?

    in short, reactants in an exothermic reaction like methane for instance, have weak bonds with high potential energy?

    Is this correct?
    Partially correct, but it is dangerous and incorrect to say that they have energy IN their bonds which can be released by breaking them.

    In my earlier post I explained that energy is released when bonds are MADE.

    If you break weak bonds and make strong ones there is an overall release of energy (exothermic)
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    (Original post by charco)
    Partially correct, but it is dangerous and incorrect to say that they have energy IN their bonds which can be released by breaking them.

    In my earlier post I explained that energy is released when bonds are MADE.

    If you break weak bonds and make strong ones there is an overall release of energy (exothermic)
    So, potential energy is essentially the amount of energy that can be potentially released into the surroundings when the bonds are broken. So is this why products have a lower PE? Because Potential energy that got converted into thermal energy (during bond cleavage in their constituent reactants) was released into the surroundings, therefore during bond formation; when making products, only a small amount of PE got stored in the bonds.

    Or is it that PE gets converted into thermal energy during bond formation? and that this means there is less PE in product bonds as a result?

    so to summarise: Reactants have bonds with higher PE, is this why their position is higher than that of the products in an energy profile diagram?
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    I don't think these analogies help because so much confusion is being created. There is electron binding energy (informally discussed as chemical potential energy), which is the energy required to remove one electron or the energy released to form a bond. This should be covered in energetics.

    The net effect in endothermic reactions is that the species, as rightfully pointed out, becomes less stable because the overall binding energy of its electron cloud becomes greater. The energy can be released in exothermic reactions where the products are more stable than the reactants.
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    (Original post by mercuryman)
    So, potential energy is essentially the amount of energy that can be potentially released into the surroundings when the bonds are broken. So is this why products have a lower PE? Because Potential energy that got converted into thermal energy (during bond cleavage in their constituent reactants) was released into the surroundings, therefore during bond formation; when making products, only a small amount of PE got stored in the bonds.

    Or is it that PE gets converted into thermal energy during bond formation? and that this means there is less PE in product bonds as a result?

    so to summarise: Reactants have bonds with higher PE, is this why their position is higher than that of the products in an energy profile diagram?
    As I keep saying, the highlighted text is WRONG.

    Energy is only released when bonds are FORMED
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    (Original post by charco)
    Partially correct, but it is dangerous and incorrect to say that they have energy IN their bonds which can be released by breaking them.

    In my earlier post I explained that energy is released when bonds are MADE.

    If you break weak bonds and make strong ones there is an overall release of energy (exothermic)
    Is this because there is excess energy i.e. due to the bonds formed being strong a lot of energy(more that is needed to break bonds) is released and some of this energy released will be used to break the 'weak' bonds and the rest of it will be released into the surrounding?
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    (Original post by zigocarn)
    Is this because there is excess energy i.e. due to the bonds formed being strong a lot of energy(more that is needed to break bonds) is released and some of this energy released will be used to break the 'weak' bonds and the rest of it will be released into the surrounding?
    more or less ..
 
 
 
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