Energetics
, Enthalpy
Enthalpy (H): The total energy of something
Enthalpy is made up of:
• Internal energy (U) - the total kinetic and potential energy of a substance
• It is impossible to measure the exact Enthalpy of a substance but it can be calculated
• You can measure the Enthalpy change in a reaction
Exothermic Reactions Endothermic reactions
• Energy has been given out • Energy has been taken in
• Bond making is exothermic • Bond breaking is endothermic
• -negative: excothermic • H endothermic
positive:
=
Enthalpy level Diagram
• Enthalpy of a reaction is not related to the rate of a reaction
Standard Conditions
• 298K and 100000Pa ·under standard
0
• Symbols: H conditions
IOO. OO OPA
298k
• Changes of state are an Enthalpy change, therefore state symbols are very important
Calorimetry
• Temperature = heat.
• Temperature is a measure of the total kinetic energy of the particles
• Heat energy is equal to the total kinetic energy of the particle
• Specific Heat Capacity: is the quantity of energy required to change the temperature of a
1g sample of something by 1 C
, Enthalpy
Enthalpy (H): The total energy of something
Enthalpy is made up of:
• Internal energy (U) - the total kinetic and potential energy of a substance
• It is impossible to measure the exact Enthalpy of a substance but it can be calculated
• You can measure the Enthalpy change in a reaction
Exothermic Reactions Endothermic reactions
• Energy has been given out • Energy has been taken in
• Bond making is exothermic • Bond breaking is endothermic
• -negative: excothermic • H endothermic
positive:
=
Enthalpy level Diagram
• Enthalpy of a reaction is not related to the rate of a reaction
Standard Conditions
• 298K and 100000Pa ·under standard
0
• Symbols: H conditions
IOO. OO OPA
298k
• Changes of state are an Enthalpy change, therefore state symbols are very important
Calorimetry
• Temperature = heat.
• Temperature is a measure of the total kinetic energy of the particles
• Heat energy is equal to the total kinetic energy of the particle
• Specific Heat Capacity: is the quantity of energy required to change the temperature of a
1g sample of something by 1 C
