AP Chemistry 6.8: Enthalpy of Formation
Practice AP Chemistry questions on calculating standard reaction enthalpy from tabulated formation enthalpies for products and reactants.
- Syllabus
- Effective Fall 2025
- Course
- AP Chemistry
Exam points
- Explain how molecular structure and periodic trends influence chemical properties and reactivity.
- Apply electron configurations, bonding models and particle interactions to predict chemical behavior.
6.8.A—Calculate the enthalpy change for a chemical or physical process based on the standard enthalpies of formation question 1
A student places a mixture of plastic beads consisting of polypropylene (PP) and polyvinyl chloride (PVC) in a 1.0 L beaker containing distilled water. After stirring the contents of the beaker vigorously, the student observes that the beads of one type of plastic sink to the bottom of the beaker and the beads of the other type of plastic float on the water. The chemical structures of PP and PVC are represented by the diagrams below, which show segments of each polymer.
PP
Using the table of standard enthalpies of formation below, determine whether the combustion of 2.00 mol of propene releases more, less, or the same amount of energy that 2.00 mol of vinyl chloride releases. Justify your answer with a calculation. The balanced equation for the combustion of 2.00 mol of propene
is \(2 \mathrm{C}_{3} \mathrm{H}_{6}(g)+9 \mathrm{O}_{2}(g) \rightarrow 6 \mathrm{CO}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)\).
All question bank results loaded