8A. Energetics I [SET 1] Flashcards
What is enthalpy change?
The heat energy change in a reaction at constant pressure
What are the units for enthalpy change?
kJmol-1
What are the standard conditions?
Elements in their standard states
100kPa
298K
What are exothermic reactions?
Give out energy, negative enthalpy change
What are endothermic reactions?
Take in energy, positive enthalpy change
What do enthalpy level diagrams show?
Overall relative change in a reaction
What does an enthalpy level diagram look like for an exothermic reaction?
Reactants higher than products
What does an enthalpy level diagram look like for an endothermic reaction?
Products higher than reactants
What do reaction profile diagrams show?
Enthalpy changes during a reaction
What is the activation energy?
The minimum energy needed for the reaction to occur
Why are standard conditions important?
Changes in temperature and pressure can affect enthalpy
What is the standard enthalpy change of reaction?
The enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation under standard conditions
What is the standard enthalpy change of formation?
The enthalpy change when one mole of a product is formed from its constituent elements in their standard states under standard conditions
What is the standard enthalpy change of combustion?
The enthalpy change when one mole of a substance is burned completely in oxygen under standard conditions
What is the standard enthalpy change of neutralisation?
The enthalpy change when an acid and an alkali react to form one mole of water under standard conditions