Exothermic/endothermic chemical reactions Watch

Freedom physics
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#1
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Please may someone explain why you have to decrease the temperature of an exothermic reaction in order to make more products? 😄, I understand that if you make more reactants the system will produce more products temporarily to adjust to the change in the system due to le chateliers principle but it still doesn't make sense because the system needs energy to break the bonds of the reactants so that it can form products but if you supply the system with less energy it's not going to have the energy required to allow energy to be absorbed thus no products can form 🙂
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Kian Stevens
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(Original post by Freedom physics)
Please may someone explain why you have to decrease the temperature of an exothermic reaction in order to make more products? 😄, I understand that if you make more reactants the system will produce more products temporarily to adjust to the change in the system due to le chateliers principle but it still doesn't make sense because the system needs energy to break the bonds of the reactants so that it can form products but if you supply the system with less energy it's not going to have the energy required to allow energy to be absorbed thus no products can form 🙂
An equilibrium has two reactions: a forward reaction and a reverse reaction. In an exothermic reaction, the forward reaction is exothermic, so the reverse reaction is endothermic. The opposite is true for an endothermic reaction.

In an exothermic reaction, you decrease the temperature to shift the equilibrium towards the forward reaction, to make more products. This is because the reverse reaction is endothermic, and so increasing the temperature will shift the equilibrium towards producing more reactants. This makes sense, since an endothermic reaction takes in more energy than it releases, so it needs all the energy it can get - the opposite is true for an exothermic reaction, since it doesn't want any additional energy, as it's already releasing more than it takes in.

Think of it this way: if you've gone for a run and you're hot and sweaty, would you go for another run to feel better? No, because this would make you even hotter. You'd do the opposite; sit, rest and cool down to feel better again.
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Freedom physics
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"In an exothermic reaction, you decrease the temperature to shift the equilibrium towards the forward reaction, to make more products. This is because the reverse reaction is endothermic, and so increasing the temperature will shift the equilibrium towards producing more reactants." (I accidentally removed the quote bracket things)

How does increasing the temperature of an exothermic reaction shift the equilibrium towards the products? Increasing the temperature of a reaction makes it so that more bonds break and consequently decreases the amount of reactant that you have and because the system has more energy to be released when the bonds of the reactants are formed energy is released, although if you decrease the temperature of the system there's less energy to be absorbed by reactant molecules when their bonds break therefore less reactant bonds would break and then there wouldn't be enough particles to react to create product molecules 😄, also please make sure to explain your answer with bond breaking and bond making involved and of course energy 🙂
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Kian Stevens
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(Original post by Freedom physics)
"In an exothermic reaction, you decrease the temperature to shift the equilibrium towards the forward reaction, to make more products. This is because the reverse reaction is endothermic, and so increasing the temperature will shift the equilibrium towards producing more reactants." (I accidentally removed the quote bracket things)

How does increasing the temperature of an exothermic reaction shift the equilibrium towards the products? Increasing the temperature of a reaction makes it so that more bonds break and consequently decreases the amount of reactant that you have and because the system has more energy to be released when the bonds of the reactants are formed energy is released, although if you decrease the temperature of the system there's less energy to be absorbed by reactant molecules when their bonds break therefore less reactant bonds would break and then there wouldn't be enough particles to react to create product molecules 😄, also please make sure to explain your answer with bond breaking and bond making involved and of course energy 🙂
Forget about it 'requiring energy' etc. The bonds will be broken and made in the reaction, regardless of whether it's a cold day or a warm day. The only time it wouldn't happen is if there was no temperature full stop, and we all know that can't happen.

I've already explained why the equilibrium shifts. The equilibrium has a forward and a reverse reaction - increasing the energy of an exothermic reaction will shift the equilibrium in the direction of the endothermic reaction, which would produce more reactants.

Did you not learn what Le Chatelier's principle actually is? If a system in dynamic equilibrium experiences a change, the equilibrium will shift to oppose that change... The exothermic reaction gives out energy, so giving it even more energy will shift the equilibrium to oppose the change... It just so happens that it'll shift in the direction of the endothermic reaction, which would produce more reactants.
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Freedom physics
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Thanks for reminding me of what le chateliers principle is! 🙂, please may you explain that first paragraph you typed more? 😄, because it implies that temperature doesn't matter which then implies that you don't have to change the temperature at all, and then there's the question of why temperature effects endothermic and exothermic reactions in different ways in the first place! 😄
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Kian Stevens
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(Original post by Freedom physics)
Thanks for reminding me of what le chateliers principle is! 🙂, please may you explain that first paragraph you typed more? 😄, because it implies that temperature doesn't matter which then implies that you don't have to change the temperature at all, and then there's the question of why temperature effects endothermic and exothermic reactions in different ways in the first place! 😄
That paragraph was merely a bit of a joke. In so many words, I was just saying that the reaction will happen regardless of what the temperature is.

Of course, some reactions favour certain temperatures. However, all reactions should happen in some shape or form, even if they're not spontaneous, providing there's energy in the system - if there's no temperature, then there's no energy, and if there's no energy, how does anything happen at all?

But let's not get hung up on the philosophics.
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Freedom physics
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Why does temperature effect exothermic and endothermic reactions then? 😄
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