molar enthlpay of formation :)

What is a molar enthalpy of formation (ΔH°f)

It’s the enthalpy change when one mole of a compound forms from its elements in their standard states.

What are the units of molar enthalpy of formation

kJ/mol

What is the enthalpy of formation of any element in its standard state

0 kJ/mol

What does “one mole” in the definition mean

The reaction must form exactly 1 mole of the compound (even if that means using fractions in the equation).

Write the formation equation for oxygen gas, O₂(g).

It’s an element in its natural form, so no formation reaction — ΔH°f = 0.

How can molar enthalpies of formation be shown visually

As an enthalpy change diagram, where: Y-axis = chemical potential energy. The height difference = ΔH of formation

How does this differ from a potential energy diagram

Potential Energy Diagram → shows reaction progress and activation energy. Formation Enthalpy Diagram → shows total enthalpy differences between compounds and their elements

What is ΔH°f used for

To calculate enthalpy changes of chemical reactions, especially when calorimetry data isn’t available.