Enthalpy
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Re: Enthalpy
They're just given as positive values, but if you're forming the bond then you would write them as negative because it is an exothermic process
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Re: Enthalpy
Bond breaking is an endothermic process ie a process that requires energy. For endothermic reactions, the products of the reaction have a greater enthalpy than the reactants, and heat is absorbed by the system from its surroundings. Therefore, the delta H b must be positive because the energy is being added to the system.
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Re: Enthalpy
Endothermic is using heat, so delta H would be positive, whereas exothermic reactions lose heat so it'll be a negative delta H.
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Re: Enthalpy
Endothermic requires heat, therefore delta H is positive.
Exothermic releases heat, therefore delta H is negative.
Whether you are forming bonds (endothermic), or breaking bonds (exothermic) you would refer to your positive/negative value of delta H.
Exothermic releases heat, therefore delta H is negative.
Whether you are forming bonds (endothermic), or breaking bonds (exothermic) you would refer to your positive/negative value of delta H.
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Re: Enthalpy
Just to add on, "enthalpy of bond" has a more formal name as "Bond Energy" and its definition is the amount of energy required to break that particular bond. Breaking of bond requires energy and hence is endothermic.
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Re: Enthalpy
In order to break bonds, you need a input of heat so thats why delta h is positive (endothermic)
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