Study resource
Energetics key terms
Use these key terms for Energetics in AQA Chemistry 7405. The page is built from approved learning objectives for this topic and links back to the wider unit, topic hub, and related revision assets.
At a glance
key terms
Resource type
Topic
Energetics
Key terms
enthalpy change
The heat energy change associated with a chemical reaction at constant pressure. In Enthalpy change, enthalpy change is used to explain define enthalpy change under constant pressure with A-Level Chemistry precision.
constant pressure
A condition where the pressure remains unchanged during a chemical reaction, allowing for accurate enthalpy change measurements.
exothermic reaction
A reaction that releases energy to the surroundings, resulting in a decrease in enthalpy.
endothermic reaction
A reaction that absorbs energy from the surroundings, resulting in an increase in enthalpy.
reaction profile diagram
A graphical representation showing the energy changes during a chemical reaction, illustrating the enthalpy change and activation energy.
activation energy
The minimum energy required for a reaction to occur, represented as the peak of the energy barrier in a reaction profile diagram.
standard enthalpy change of formation
The enthalpy change when one mole of a compound is formed from its elements in their standard states.
standard enthalpy change of combustion
The enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions.
heat energy transferred
The amount of thermal energy exchanged during a process, calculated using the formula q = mcΔT.
specific heat capacity
The amount of heat required to raise the temperature of 1 kg of a substance by 1 °C, represented by the symbol c in the formula q = mcΔT.
molar enthalpy change
The amount of energy transferred as heat per mole of substance during a reaction at constant pressure.
calorimetry
The science of measuring the heat of chemical reactions or physical changes. In Calorimetry and enthalpy measurements, calorimetry is used to explain convert calorimetry data into molar enthalpy changes with A-Level Chemistry precision.
enthalpy change
The heat change associated with a chemical reaction at constant pressure. In Calorimetry and enthalpy measurements, enthalpy change is used to explain use appropriate units and significant figures in enthalpy calculations with A-Level Chemistry precision.
significant figures
The digits in a number that carry meaningful information about its precision. In Calorimetry and enthalpy measurements, significant figures is used to explain use appropriate units and significant figures in enthalpy calculations with A-Level Chemistry precision.
calorimetry
The science of measuring the heat of chemical reactions or physical changes. In Calorimetry and enthalpy measurements, calorimetry is used to explain explain practical limitations and heat loss in calorimetry with A-Level Chemistry precision.
heat loss
The energy that is lost to the surroundings during a calorimetry experiment, affecting the accuracy of measurements.
enthalpy change
The heat change associated with a chemical reaction at constant pressure. In Calorimetry and enthalpy measurements, enthalpy change is used to explain required practical: measure an enthalpy change with A-Level Chemistry precision.
calorimetry
The measurement of heat changes during chemical reactions or physical changes. In Calorimetry and enthalpy measurements, calorimetry is used to explain required practical: measure an enthalpy change with A-Level Chemistry precision.
Hess's law
The total enthalpy change for a reaction is the sum of the enthalpy changes for the individual steps, regardless of the pathway taken.
enthalpy change
The heat change associated with a chemical reaction at constant pressure, typically measured in kilojoules per mole (kJ/mol).
Hess's law
The total enthalpy change for a reaction is the sum of the enthalpy changes for each step of the reaction, regardless of the pathway taken.
enthalpy change
The heat change associated with a chemical reaction at constant pressure, typically measured in kilojoules per mole (kJ/mol).
enthalpy change
The heat change associated with a chemical reaction at constant pressure. In Applications of Hess's law, enthalpy change is used to explain calculate enthalpy changes from enthalpies of combustion with A-Level Chemistry precision.
Hess's law
The principle stating that the total enthalpy change for a reaction is the same, regardless of the number of steps taken.
enthalpy change
The heat change associated with a chemical reaction at constant pressure. In Applications of Hess's law, enthalpy change is used to explain calculate enthalpy changes from enthalpies of formation with A-Level Chemistry precision.
enthalpy of formation
The enthalpy change when one mole of a compound is formed from its elements in their standard states.
enthalpy cycle
A diagram that represents the enthalpy changes of a reaction, showing the relationship between reactants, products, and intermediate states.
Hess's law
A principle stating that the total enthalpy change for a reaction is the same, regardless of the number of steps taken, allowing for the calculation of enthalpy changes from known values.
mean bond enthalpy
The average energy required to break one mole of a specific type of bond in a gaseous molecule.
enthalpy change
The heat change associated with a chemical reaction at constant pressure, measured in kilojoules per mole (kJ/mol).
mean bond enthalpy
The average energy required to break one mole of a specific type of bond in a gaseous molecule.
enthalpy change
The heat change associated with a chemical reaction at constant pressure, typically measured in kJ/mol.
bonds broken
The bonds that are cleaved during a chemical reaction, requiring energy input to break.
bonds formed
The bonds that are created during a chemical reaction, releasing energy when formed. In Bond enthalpies, bonds formed is used to explain distinguish bonds broken from bonds formed in bond enthalpy calculations with A-Level Chemistry precision.
mean bond enthalpy
The average energy required to break one mole of a specific type of bond in a gaseous molecule.
Hess's law
A principle stating that the total enthalpy change during a chemical reaction is the same, regardless of the number of steps taken.
Related topics