Energetic Explorations: Unraveling Enthalpy Changes

Energetic Explorations: Unraveling Enthalpy Changes

Learning Objective

Understand standard enthalpy changes of combustion, ΔHc⦵, and formation, ΔHf⦵. Calculate enthalpy changes of a reaction using ΔHf⦵ data or ΔHc⦵ data.

What do you already know about enthalpy changes and their significance in chemical reactions?

What is the equation to calculate the enthalpy change of a reaction using standard enthalpy of formation data?

1. ΔH⦵ = Σ ΔHf⦵reactants + Σ ΔHf⦵products
2. ΔH⦵ = Σ ΔHc⦵reactants − Σ ΔHf⦵products
3. ΔH⦵ = Σ ΔHc⦵reactants + Σ ΔHf⦵products
4. ΔH⦵ = Σ ΔHf⦵products − Σ ΔHf⦵reactants

Which term is not included in the construction of a complete Born–Haber cycle?

1. Electron affinities
2. Enthalpy of atomization
3. Lattice enthalpy
4. Ionization energies

What is the equation to calculate the enthalpy change of a reaction using standard enthalpy of combustion data?

1. ΔH⦵ = Σ ΔHc⦵reactants − Σ ΔHf⦵products
2. ΔH⦵ = Σ ΔHf⦵reactants + Σ ΔHf⦵products
3. ΔH⦵ = Σ ΔHf⦵products − Σ ΔHf⦵reactants
4. ΔH⦵ = Σ ΔHc⦵reactants + Σ ΔHf⦵products

: Understand standard enthalpy changes of combustion, ΔHc⦵, and formation, ΔHf⦵. Deduce equations and solutions to problems involving these terms.

2: Calculate enthalpy changes of a reaction using ΔHf⦵ data or ΔHc⦵ data:
ΔH⦵ = Σ ΔHf⦵products − Σ ΔHf⦵reactants

ΔH⦵ = Σ ΔHc⦵reactants − Σ ΔHf⦵products.


3: Understand a Born–Haber cycle for an ionic compound. Interpret and determine values from a Born–Haber cycle for compounds composed of univalent and divalent ions, including: ionization energies, enthalpy of atomization, electron affinities, lattice enthalpy, enthalpy of formation. The construction of a complete Born–Haber cycle will not be assessed.

Enthalpy Changes of Combustion

ΔH⦵ = Σ ΔHc⦵reactants - Σ ΔHf⦵products. This equation helps us calculate enthalpy changes of a combustion reaction.

Enthalpy Changes of Formation

ΔH⦵ = Σ ΔHf⦵products - Σ ΔHf⦵reactants. This equation helps us calculate enthalpy changes of a formation reaction.

Applying Enthalpy Equations

We can deduce equations and solutions to problems involving enthalpy changes using the given formulas and data.

Born–Haber Cycle

A Born–Haber cycle helps us interpret and determine values for compounds involving ionization energies, electron affinities, and more.

Energetics of Ionic Compounds

The cycle aids in understanding enthalpy of atomization, electron affinities, lattice enthalpy, and enthalpy of formation for ionic compounds.

Interpreting Born–Haber Cycle

Students will learn how to interpret and determine values from a Born–Haber cycle for compounds composed of univalent and divalent ions.

Lesson Recap

Recap the key concepts covered in the lesson and reinforce understanding of enthalpy changes and Born–Haber cycles.

Write down 3 things you learned in this lesson.

Have students enter three things they learned in this lesson. With this they can indicate their own learning efficiency of this lesson.

Write down 2 things you want to know more about.

Here, students enter two things they would like to know more about. This not only increases involvement, but also gives them more ownership.

Ask 1 question about something you haven't quite understood yet.

The students indicate here (in question form) with which part of the material they still have difficulty. For the teacher, this not only provides insight into the extent to which the students understand/master the material, but also a good starting point for the next lesson.