2.1- Thermochemistry Flashcards
(a)
Enthalpy change
The heat energy change measured at constant pressure.
(a)
Standard conditions
A pressure of 1 atm
A stated temperature of 298K
A standard concentration of 1 mol dm-3 for solution.
(a)
Exothermic reaction
A reaction in which energy is released to the surroundings.
(a)
Endothermic reactions
A reaction in which energy is taken in from the surroundings.
(a)
Definition of the standard enthalpy change of reaction
The enthalpy change that occurs when the molar quantities react under standard conditions, with all reactants and products in their standard states.
(a)
Definition of the standard enthalpy change of formation
The enthalpy change when one mole of product is formed from its elements with all reactants and products in their standard states, under standard conditions.
(a)
Definition of the standard enthalpy change of combustion
The enthalpy change that occurs when one mole of compound is completely reacted with excess oxygen under standard conditions with all reactants and products in their standard states.
(a)
Definition of the standard enthalpy change of neutralisation
The enthalpy change which occurs when an acid and alkali react under standard conditions to produce 1 mole of water.
(d)
Equation used to work out the energy transferred in a reaction
q = mc𝚫T
q = energy released/absorbed (J)
m = mass (g)
c = specific heat capacity (J g-1 °C-1) 𝚫T = temperature change (°C)
