Enthalpy changes and bond enthalpy

What is enthalpy (H)?

Enthalpy is the total heat content of a system, a measure of the energy stored in a substance.

What does the symbol ΔH represent?

ΔH represents the change in enthalpy during a chemical reaction.

What is an exothermic reaction?

An exothermic reaction is a process that releases heat, resulting in a negative ΔH.

What is an endothermic reaction?

An endothermic reaction is a process that absorbs heat, resulting in a positive ΔH.

How is bond enthalpy defined?

Bond enthalpy is the amount of energy required to break one mole of a specific bond in a molecule.

What is the relationship between bond forming and enthalpy?

Bond formation releases energy, contributing to a decrease in enthalpy.

What does a positive ΔH indicate about a reaction?

A positive ΔH indicates that the reaction absorbs energy, characterizing an endothermic process.

What does a negative ΔH indicate about a reaction?

A negative ΔH indicates that the reaction releases energy, characterizing an exothermic process.

What is the standard enthalpy of formation?

It is the change in enthalpy when one mole of a compound is formed from its elements in their standard states.

How can the enthalpy change of a reaction be calculated?

It can be calculated using the formula: ΔH = Σ(bond enthalpies of bonds broken) - Σ(bond enthalpies of bonds formed).