ENERGETICS
Keywords
● Heat: Amount of energy transferred between hot to cold (between
system to surrounding)
● Temperature: Average kinetic energy of all particles in a substance
● Enthalpy: Heat content of a system
● Open system: Where mater and energy can move freely between the
system and surrounding
● Closed system: Where energy moves freely between then system
and surrounding
● Isolated system: Where there is no exchange of energy or matter
Exothermic reactions
● Energy is released
● Negative delta H/enthalpy
● Formation of bonds
● Temperature increases
Endothermic reactions
● Energy is absorbed
● Positive delta H/enthalpy
● Breaking of bonds
● Temperature decreases
, Standard enthalpy
● 100 kpa
● 298 k
● 1 mol dm-3
● All substances in standard state
Bond enthalpy
● Energy needed to break 1 mol of covalent bond in a gaseous
molecule
● Values are averages therefore are not specific for each compound
Formation reaction
● The energy change when 1 mol of a substance is formed in its
standard state from its element in their standard state under standard
conditions
Keywords
● Heat: Amount of energy transferred between hot to cold (between
system to surrounding)
● Temperature: Average kinetic energy of all particles in a substance
● Enthalpy: Heat content of a system
● Open system: Where mater and energy can move freely between the
system and surrounding
● Closed system: Where energy moves freely between then system
and surrounding
● Isolated system: Where there is no exchange of energy or matter
Exothermic reactions
● Energy is released
● Negative delta H/enthalpy
● Formation of bonds
● Temperature increases
Endothermic reactions
● Energy is absorbed
● Positive delta H/enthalpy
● Breaking of bonds
● Temperature decreases
, Standard enthalpy
● 100 kpa
● 298 k
● 1 mol dm-3
● All substances in standard state
Bond enthalpy
● Energy needed to break 1 mol of covalent bond in a gaseous
molecule
● Values are averages therefore are not specific for each compound
Formation reaction
● The energy change when 1 mol of a substance is formed in its
standard state from its element in their standard state under standard
conditions
