Energetics Flashcards
Definition of Enthalpy Change
The heat energy transferred in a reaction at constant pressure
The Standard Conditions for Enthalpy Change -o-
100 kPa (1 atm) and a stated temperature
The value of the Enthalpy Change for an Exothermic Reaction
-
The value of the Enthalpy Change for an Endothermic Reaction
+
Definition of Bond Enthalpy
The energy needed to break a bond
What happens when you break bonds
Energy is needed to break the bond, so it is endothermic and +
What happens when you make bonds
Energy is released, so it is exothermic and -
Definition of mean Bond Enthalpy
The average energy needed to break a certain type of bond over a range of compounds
Equation for calculating Enthalpy Change
Enthalpy change of reaction = total energy absorbed - total energy released
Definition of Standard enthalpy change of Formation
the enthalpy change when 1 mole of compound is formed from its elements in their standard states under standard conditions
Definition of Standard enthalpy change of Combustion
the enthalpy change when 1 mole of compound is completely burned in oxygen with all reactants and products in their standard states under standard conditions
Definition of Standard enthalpy change of Reaction
the enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation under standard conditions with all reactants and products in their standard states
Description of the measuring enthalpy change practical
The Equation for
q = mc(delta)T
How to measure an enthalpy of neutralisation
- add a known volume of acid into an insulated container and measure the temperature
- add a known volume of alkali and record the temperature at intervals, stir to make sure it is evenly heated
- work out temperature change and then work out the energy given out using q = mc(delta)T
