Topic A2 - Energetics Flashcards
(17 cards)
What are the standard conditions for measuring enthalpy?
100kPa pressure, 298K
What is the nature of energy change when bonds are broken?
Endothermic as energy is absorbed
What is the nature of energy change when bonds are made?
Exothermic as energy is released
How is enthalpy change calculated?
Enthalpy change = bonds broken - bonds made
What is activation energy?
Minimum energy required for a reaction to take place between two colliding reactant particles
Define the enthalpy change of reaction.
Enthalpy change associated with a stated reaction, quantities of substances in standard states react completely under standard conditions
What is the enthalpy change of formation?
Enthalpy change when one mole of substance is produced from its elements in their standard states under standard conditions
What is the enthalpy change of combustion?
Enthalpy change when one mole of substance is burned completely in oxygen under standard conditions
What is the enthalpy change of neutralization?
Enthalpy change when solutions of acid and alkali react together under standard conditions to produce one mole of water
What does calorimetry measure?
Measures temperature change over time to find enthalpy change
What is the equation used to calculate heat transfer?
Q = mcΔT
What does ‘c’ represent in the equation Q = mcΔT?
Specific heat capacity (energy required to raise 1g of substance by 1K without a change of state)
How is ΔH calculated in terms of heat transfer?
ΔH = - (Q) / moles
What is a source of error in calorimetry?
Heat loss via conduction or convection
How can heat loss in calorimetry be reduced?
By putting a lid on calorimeter or insulating outsides (e.g. polystyrene)
What is another source of error in calorimetry?
Inaccuracies in measuring temperature
What does bond enthalpy refer to?
Energy required to break one mole of the stated bond in a gaseous state, under standard conditions
