Breaking and Making Bonds

Part of the Energy, Rates and Equilibrium section of Coddy's Chemistry journey. Lesson 6 of 35.

Breaking a bond takes in energy; making one gives out the same amount.

The bond energy is the energy to break a mole of that bond: H-H $436\ \mathrm{kJ/mol}$ , C-H $413\ \mathrm{kJ/mol}$ , O-H $464\ \mathrm{kJ/mol}$ .

To break a molecule into atoms, add all its bonds: CH₄ has four C-H, so 4 × 413 = $1652\ \mathrm{kJ}$ .

Challenge

How much energy $B$ does it take to break every bond in one mole of methane, CH₄ (C-H: $413\ \mathrm{kJ/mol}$ )?

Try it yourself

Solve for $B$

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Energy, Rates and Equilibrium

1Energy in Reactions

Exothermic and Endothermic Energy Diagrams Enthalpy Change Activation Energy Recap - Hand Warmer

4Rates of Reaction

Collision Theory Concentration and Rate Temperature and Rate Surface Area Catalysts Recap - Speed Trials

7Practice Problems

Recap - Methanol Plant Recap - Butane Lighter Recap - Limestone Kiln

2Bond Energies

Breaking and Making BondsDelta H from Bond Energies Hess's Law Energy and Moles Recap - Fuel Value

5Equilibrium

Reversible Reactions Dynamic Equilibrium The Equilibrium Constant Writing K Solids and Liquids in K Recap - K Builder

3Changes of State

Heating Curves Melting and Boiling Energy of State Changes Recap - Ice to Steam

6Changing an Equilibrium

Le Chatelier's Principle Changing Concentration Changing Pressure Changing Temperature The Haber Process Recap - Factory Settings