Enthalpy Flashcards
What is an exothermic reaction
When energy transferred to the surroundings is more than the energy taken in
What is an endothermic reaction
When energy transferred to the surroundings is less than the energy taken in
What is the activation energy
Minimum energy required for a reaction to take place
Define standard conditions
100kPa
298 K
1moldm-3
What is the enthalpy change of reaction
The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard states.
What is the enthalpy change of formation
The enthalpy change that takes place when 1 mole of a compound is formed from its elements under standard conditions
What is the enthalpy change of combustion
the enthalpy change that takes place when 1 mole of a substance reacts completely with oxygen under standard conditions
What is the enthalpy change of neutralisation
the enthalpy change when an acid and base react to form 1 mole of H2O under standard conditions
Describe a Calorimetric method
Measure 150cm3 of water and pour into beaker
Record initial temp
Record spirit burner mass
Light spirit burner for 3 mins
Extinguish flame and record mass of spirit burner and final temp
Sub values into q = mct
What is average bond enthalpy
The amount of energy needed to break 1 mol of bonds in gaseous molecules
What is Hess’s law
The idea that the enthalpy change for a reaction is independent of the route taken
