Hf vs H
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Hf vs H
I'm confused on when the Hf and H would be different if we knew the composition of the products and reactants. If someone has an example of a problem where only Hf is applicable and a problem where only H is applicable and is willing to share, I would really appreciate it!
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Re: Hf vs H
I assume that you are confused about the difference in enthalpy (H) and enthalpy of fusion (Hf). Essentially, Hf would be used if the reaction of interest is a fusion/melting reaction specifically. H is a much more encompassing term that includes all reactions. I do not think that it would be a problem if you stated ∆H instead of ∆Hf for a melting reaction unless stated otherwise. Hope this helps!
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Re: Hf vs H
You would use ΔH°(standard reaction enthalpy) when all of the reactants and products are in their standard state at 1 atm, in which most reactions are given. I believe that ΔH°f (standard enthalpy of formation) is applicable when you are finding the enthalpy of the formation of 1 mole of a substance, in which its elements are in their most stable form.
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Re: Hf vs H
Standard enthalpy of formation (delta Hf) is specific to the formation of one mole of a substance from its elements in their most stable forms and standard reaction enthalpy is measuring the enthalpy change when the reaction is taking place under standard conditions (1 ATM and usually 25 degrees celsius). One method of calculating delta H is using the standard enthalpies of formation (subtract the delta Hf of reactants from that of products).
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