Thermodynamics Flashcards
Define standard enthalpy of atomisation
The enthalpy change when mole of gaseous atoms is formed from the element in its standard state under standard conditions
Define first electron affinity
The standard enthalpy change when one mole of gaseous atoms is converted into one mole of gaseous ions, each with a single negative charge
Define second electron affinity
The enthalpy change when mole of electrons is added to one mole of gaseous ions, each with a single negative charge to form one mole of gaseous ions each with 2 negative charges
Define first ionisation energy
The standard enthalpy change when one mole of gaseous atoms is converted into one mole of gaseous ions each carrying a single positive charge
Is first ionisation energy an endo- or exothermic reaction?
Endothermic
Is first electron affinity an endo- or exothermic reaction?
Exothermic
Is second electron affinity an endo- or exothermic reaction?
Endothermic
Why is second electron affinity endothermic?
Involves bringing together 2 negative charges - naturally these want to repel
What should you look for in entropy changes?
Look out for the number of moles on the reactants and products side. Also look out for state changes.
What suggests an increase in entropy change?
If the total number of moles of the reactants is less than the number of moles of the products. If a state change is experienced. Entropy increases in this general order: solid -> liquid -> aqueous -> gas
What suggests a decrease in entropy change?
If the total number of moles of the reactants is more than the total number of moles of the products. If a state change is experienced. Entropy decreases in this general order: gas -> aqueous -> liquid -> solid
What is the equation for gibbs free energy?
G = H-TS
What is the enthalpy of lattice dissociation?
Enthalpy of lattice dissociation is the standard enthalpy change when one mole of an ionic crystal lattice form is separated into its constituent ions in gaseous form.
