Energetics Flashcards
State the definition of Enthalpy of Formation
Enthalpy change when 1 mole of a substance is formed from its constituent elements with all reactants and products in standard states under standard conditions
State the definition of Enthalpy of Combustion
Enthalpy change when 1 mole of a substance I completely burned in oxygen with all reactants and products in standard states under standard conditions
State the definition of Enthalpy of Neutralisation
Enthalpy change when 1 mole of water is formed in a reaction between An acid and alkali under standard conditions
State the definition of Enthalpy change
Heat energy change of a chemical reaction measured under constant pressure
Name the 2 equations used to calculate enthalpy change
q = m X c X Delta T —> q / n = delta H
What is Hess’ Law
The overall enthalpy change is independent of the route taken
What does Bond enthalpies mean
The Enthalpy change when 1 mol of a particular covalent bond is broken in the gaseous state.
State some facts about bond enthalpies
- Shorter bond lengths gave a high enthalpy
- Reactants and products must be in the gaseous state
- Values will be less accurate as mean values are used
What is the formula for bond enthalpy?
Delta H = (Sum of Delta H bonds broken) - (Sum of Delta H bond made)
What are the Standard Conditions?
100kPa
298K
State the definition of Standard Enthalpy of Reaction?
Enthalpy change when a reaction occurs in the mole ratios shown in the equation under standard states and standard conditions
