Given the following heat of formation values, calculate the heat of reaction for:?

C3H8(g) + O2(g) → CO2(g) + H2O(l)
ΔHf values in kJ/mol for:
C3H8(g) = -103.8, O2(g) = 0, CO2(g) = -393.5, H2O(l) = -285.8.

1 Answer
anor277
Dec 9, 2017

#DeltaH_"reaction"^@=SigmaDeltaH_"f"^@"products"-SigmaDeltaH_"f"^@"reactants"#

Explanation:

And you have quoted the thermodynamic parameters we need to make this summation....

#C_3H_8(g)+5O_2(g) rarr 3CO_2(g) + 4H_2O(l)#

And so we takes #{[(-4xx285.5)-(3xx393.5)]-[(-103.8)+(5xx0)] }*kJ*mol^-1#

(NB #DeltaH_f("element in its standard state")^@=0#)

#DeltaH_"rxn"^@=-2218.9*kJ*mol^-1#...

You have got to watch the minus signs when you do these summations. It is all to easy to add when you should subtract. If I have made an error someone will cry foul.

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