Enthalpy And Entropy Flashcards
(21 cards)
What is the enthalpy change of atomisation, ΔatHθ?
The enthalpy change when one mole of gaseous atoms forms from an element in its standard state.
What is the enthalpy change of lattice formation, ΔlattHθ?
The enthalpy change when one mole of an ionic compound forms from its constituent gaseous ions.
What is bond dissociation enthalpy?
The enthalpy needed to break one mole of a bond to give separated atoms, with everything in the gaseous state.
What is the enthalpy change of formation, ΔfHθ?
The enthalpy change when one mole of a compound forms from its constituent elements in their standard state.
What is the first ionisation energy?
The enthalpy change when one mole of gaseous positive ions forms from one mole of gaseous atoms.
What is the enthalpy change of hydration, ΔhydHθ?
The enthalpy change when one mole of gaseous ions dissolves in enough water to give an infinitely dilute solution.
What is the enthalpy change of solution, ΔsolHθ?
The enthalpy change when one mole of an ionic substance dissolves completely in water to form a solution.
What is the first electron affinity?
The enthalpy change when one mole of gaseous negative ions forms from one mole of gaseous atoms.
What is the Born-Haber cycle?
An energy cycle that combines the enthalpy changes involved in the formation of ionic compounds from their elements.
What does a more negative enthalpy change of formation indicate?
The more stable the compound is.
What is entropy represented by?
The symbol S, with the unit J K–1 mol–1.
How is the order of entropy for states of matter ranked?
S(gas) > S(liquid) > S(solid).
What is Gibbs free energy change, ΔG?
The balance between enthalpy, entropy, and temperature that determines the spontaneity of a reaction.
What is the formula for Gibbs free energy change?
ΔG = ΔH - TΔS.
What does a positive ΔG indicate?
The reaction is not spontaneous.
What happens to ΔG when a reaction becomes feasible?
ΔG changes from positive to negative.
What is the relationship between ΔsolHθ, ΔlattHθ, and ΔhydHθ?
ΔsolHθ = ΔlattHθ + ΔhydHθ.
Fill in the blank: If the enthalpy change of solution, ΔsolHθ, is ______, an ionic compound will be soluble.
negative
What factors affect the enthalpy change of solution?
- Enthalpy change of lattice breaking (endothermic)
- Enthalpy change of hydration (exothermic)
True or False: The second electron affinity is exothermic.
False
What is the significance of temperature in Gibbs free energy?
It can cause a reaction with a positive ΔG to occur if changed.
