Print Page - Unit 6 - AP Chemistry - enthalpy of combustion and enthalpy of formation

Title: Unit 6 - AP Chemistry - enthalpy of combustion and enthalpy of formation
Post by: gcs.redmond@gmail.com on January 19, 2026, 04:36:35 PM

I am confused about how to do this kind of question. How do I approach this?Screenshot 2026-01-19 133544.png

Title: Re: Unit 6 - AP Chemistry - Formation enthalpies question
Post by: uma on January 20, 2026, 07:39:48 AM

This question is based on formation enthalpies.
First right the balanced equation
C3H8(g)+5O2(g) → 3CO2(g)+4H2O(g)
Use the formation-enthalpy equation
Formation enthalpies equation.jpg
here apply the coefficients of the balanced equation
Plug in the values from the given table and you will get ΔH⁰comb in kJ / mol
Answer should be in kJ/g so convert 1mol into grams.
All questions based on formation enthalpies are done by using the equation given above.

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Chemistry Homework Help => AP Chemistry => Topic started by: gcs.redmond@gmail.com on January 19, 2026, 04:36:35 PM