Energetics Flashcards
Key definitions of enthalpy
Define enthalpy
Heat/energy exchange with surroundings under constant pressure.
Define standard enthalpy change of formation
Enthalpy that occurs when one mole of compounds is formed from its element under standard conditions with everything in its standard state.
Define standard enthalpy change of combustion
Enthalpy change which occurs when one mole of compound is burned completely with oxygen under standard condition and everything in its standard state.
Define standard enthalpy change of neutralisation
Enthalpy change of when solution of acid reacts with solution of alkali under standard conditions to form one mole of water.
Define enthalpy change of reaction
Enthalpy change which occurs when equation quantitates of material react under standard conditions and with everything under a standard state.
What is dynamic equilibrium?
When forward and backward reaction occur at same rate so concentrations of all reactants and products is constant.
Only be reached in a closed system
What did Le Chatelier suggest?
If reaction at equilibrium subjected to a change in concentration, pressure or temperature, the position of equilibrium will move to counteract change.
Methanol synthesis
Maximise yield
50-100 atmosphere
250C compromise
Low temp + high pressure
Ethanol synthesis
Catalyst of phosphoric acid
300C
60-70 atm
High yield favoured by lower temp
How to work out partial pressure?
PP = mole fraction x total pressure
