Hess Law Flashcards
What is an enthalpy change?
The amount of heat energy released or taken in per mole of substance during a physical or chemical change
What is an exothermic reaction?
If heat energy is given out and the temperature of the surroundings increase
What is an endothermic reaction?
The temperature of the surroundings decreases
What is the enthalpy change of formation?
The change in energy when one mole of a compound is formed from its elements in their standard states
What is the enthalpy change of combustion?
The change in energy when one mole of a substance is burnt completely in oxygen
What is bond enthalpy?
The change in energy when one mole of gaseous covalent bonds is broken
What does Hess’ Law state?
The enthalpy change during a chemical change is independent of the steps taken
What is a Hess cycle?
A visual representation of the law
What is the definition of enthalpy of vaporisation?
The energy change when one mole of a liquid is boiled to form a gas
