HESS LAW

Chemistry

Hess's Law

A principle stating that the total enthalpy change for a reaction is the sum of the enthalpy changes for individual steps of the reaction.

Enthalpy (ΔH)

A measure of the total heat content of a system, used to quantify the energy changes in a reaction.

Thermochemical data

Information related to the heat change during chemical reactions, often including values of enthalpy for specific chemical processes.

Combustion reaction

A reaction that involves the burning of a substance in oxygen to produce heat, typically forming water and carbon dioxide.

Standard enthalpy change

The change in enthalpy when reactants in their standard states are converted to products in their standard states.

ΔH = ΣΔH products - ΣΔH reactants

The formula representing the calculation of standard enthalpy change for a chemical reaction, based on the enthalpies of products and reactants.

Exothermic reaction

A chemical reaction that releases energy to its surroundings, usually in the form of heat.

Endothermic reaction

A chemical reaction that absorbs energy from its surroundings, resulting in a decrease in temperature.

Formation reaction

A reaction that produces one mole of a compound from its elements in their standard states.

Stoichiometric coefficients

Numbers in a balanced chemical equation that represent the ratio of moles of reactants and products.