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exothermic/endothermic reactions GCSE chem...im kinda confused?

if in an exothermic reaction heat is given off, does the actual thing become warmer and cooler? and also what effect does it have on the surroundings, do they get warmer or cooler? because I was just really confused and I searched it up but didn't understand it. Thanks!
Original post by vix.xvi
if in an exothermic reaction heat is given off, does the actual thing become warmer and cooler? and also what effect does it have on the surroundings, do they get warmer or cooler? because I was just really confused and I searched it up but didn't understand it. Thanks!


An exothermic reaction gives off energy in the form of heat. Therefore the surrounding will warm up. Think of a combustion reaction such as a camp fire.
(edited 4 years ago)
Original post by ElNiñoo
An exothermic reaction gives off energy in the form of heat. Therefore it will warm up and also the surrounding will warm up. Think of a combustion reaction such as a camp fire.

does the actual thing cool down then, in an exothermic reaction, because it is giving off heat?
Reply 3
In an exothermic reaction, the enthalpy change is negative, therefore heat is given off from the reactant to the surroundings. So the surroundings increase in temperature and the reactant decreases in temperature.
In an endothermic reaction, the enthalpy change is positive, therefore heat is taken in from the surroundings into the reactant. So the surroundings decrease in temperature and the reactant increases in temperature.
Original post by vix.xvi
does the actual thing cool down then, in an exothermic reaction, because it is giving off heat?


Yes.
Reply 5
What is the 'actual thing'? You're using a very vague term.
Original post by Tolgarda
What is the 'actual thing'? You're using a very vague term.

im assuming OP means the reactant
Reply 7
Original post by mez_merising
im assuming OP means the reactant

Oh...

The above posts explain it pretty well then.
Original post by Deggs_14
In an exothermic reaction, the enthalpy change is negative, therefore heat is given off from the reactant to the surroundings. So the surroundings increase in temperature and the reactant decreases in temperature.
In an endothermic reaction, the enthalpy change is positive, therefore heat is taken in from the surroundings into the reactant. So the surroundings decrease in temperature and the reactant increases in temperature.

ohhh got it thanks!
Original post by ElNiñoo
Yes.

thanksss!
You’ve hit upon an excellent point. When an exothermic reaction happens, the energy starts off in the system (with the products moving or spinning at high speed). So the system is extremely hot immediately after the reaction.

I’m defining the system as ‘those entities involved in the reaction, i.e., the atoms/ions in the reactants and the products’.
The system is anything else.

This excess thermal energy is transferred into the surroundings gradually, through conduction/radiation. Overall, the system loses thermal energy, so the reaction is exothermic. The system does not cool below the temperature of the surroundings.

Just because a reaction is described as exothermic does not mean that the transfer of energy is instantaneous.
strange thread.
When a reaction produces heat, it doesn't typically "transfer" heat from the reactants to the surroundings, the energy required to produce the increase in temperature comes from the bonds in the reactants in some way, not from the heat/temperature the reactants already have. When energy is released it heats the system. Whatever happens afterwards is just regular transfer of heat due to a temperature difference.
(edited 4 years ago)
An exothermic reaction involves a transformation of chemical potential energy into heat energy.
Potential energy, is not detectable in any way. Hence the energy transformation involves the system heating up.

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