Enthalpy & Exothermic Reactions
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Re: Enthalpy & Exothermic Reactions
Hi, I think that when a reaction is exothermic the enthalpy change would be -∆H, and so endothermic would be +∆H. So basically if the enthalpy is negative, it would be an exothermic reaction.
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Re: Enthalpy & Exothermic Reactions
enthalpy is the heat of a system and exothermic means a reaction releases heat. so an exothermic reaction will have a negative change in enthalpy to show the system lost heat.
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Re: Enthalpy & Exothermic Reactions
How can you tell when a reaction is consider exothermic or endothermic without being given the enthalpy? For instance, if a problem gives you the a reaction of HA-> H + A, what can you assume about the reaction.
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Re: Enthalpy & Exothermic Reactions
Enthalpy is the heat of a system. Enthalpy change (delta H) is the heat transferred in and out of a system. Exothermic reactions release heat, which means heat is exiting the system and therefore the enthalpy change is negative.
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Re: Enthalpy & Exothermic Reactions
Exothermic reactions indicate that heat is exiting a system. Thus, the value for the final enthalpy state of the system would be -∆H. If a reaction was endothermic, heat is entering the system, so it can be considered a reactant of the system. The final enthalpy change of the system would be +∆H. The value is positive because heat isn't exiting the system, thus the change in enthalpy isn't decreasing value.
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Re: Enthalpy & Exothermic Reactions
When a reaction is exothermic, enthalpy will be a negative number because heat is leaving the system. On the other hand, if a system is endothermic, it is gaining heat, and therefore enthalpy is positive.
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Re: Enthalpy & Exothermic Reactions
When the enthalpy is negative, that means the reaction is exothermic since the system is releasing heat. The enthalpy is positive when the reaction is endothermic because it needs to absorb heat into the system.
Re: Enthalpy & Exothermic Reactions
Enthalpy is the total amount of energy in the system. When applied to the equation G=H-TS, a negative change in enthalpy will result in an exothermic reaction as energy is lost in the system after the reaction has taken place.
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Re: Enthalpy & Exothermic Reactions
Enthalpy is the heat transferred and if you are looking at the reaction from the perspective of the system and the system is exothermic then heat is being transferred out of the system, therefore the enthalpy will be negative.
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Re: Enthalpy & Exothermic Reactions
Enthalpy is the heat transferred in or out of the system, and if you look at the reaction from the system's perspective and the system is exothermic, heat is being transported out of the system, therefore the enthalpy will be negative, because the system is losing that heat.
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Re: Enthalpy & Exothermic Reactions
Enthalpy is related to the amount of heat absorbed or released during a reaction. If the delta H or change in enthalpy is negative, that means that the reaction is exothermic as heat is being released into the surroundings and the system is losing heat.
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Re: Enthalpy & Exothermic Reactions
Enthalpy is defined as the heat of a system. If a system is exothermic, it is releasing energy likely in the form of heat. Thus, the change in enthalpy(deltaH) of the system would be negative.
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Re: Enthalpy & Exothermic Reactions
An exothermic reaction would have a negative enthalpy change because the process is releasing heat. And vice versa, an endothermic reaction would have a positive enthalpy change because the process is absorbing heat.
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Re: Enthalpy & Exothermic Reactions
An exothermic reaction describes a reaction which is releasing heat from the surroundings to the system. Enthalpy describes the heat of a system, so an exothermic reaction would have a -, because it releases heat into the surroundings from the system.
Re: Enthalpy & Exothermic Reactions
Usually, -delta H means -delta G, as enthalpy is a larger number than delta S in most cases as it is in kJ, not J/K. It takes a massive -delta S for a exothermic reaction to be nonspontaneous(+delta G)
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Re: Enthalpy & Exothermic Reactions
Enthalpy is the study of heat released or absorbed in a chemical reaction. There are endothermic and exothermic reactions. Exothermic reactions are reactions where heat is released, and a good way to remember this is that EXO in exothermic stands for exocytosis. That means something is leaving, and in this case, heat is leaving. Endothermic reactions are the opposite and deal with heat being required for a reaction to occur. Therefore, when heat is released in exothermic reactions, the enthalpy change is negative delta H, and for endothermic reactions, the enthalpy change is positive delta H. Hope this helps:)
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Re: Enthalpy & Exothermic Reactions
A reaction's enthalpy refers to the energy needed to break bonds minus the energy released by forming new bonds. An exothermic reaction would occur if the reaction releases a greater amount of energy through the formation of bonds than it absorbs when it breaks bonds. This value would be negative.
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