Thermodynamics

• What is enthalpy of formation?


  The enthalpy change when one mole of a substance is formed from its elements with all substances in their standard states, under standard conditions.
• Is enthalpy of formation exothermic or endothermic?


  Exothermic for most substances
• What is the symbol for enthalpy of formation?

  
• What is the equation for the enthalpy of formation for Na^2O(s)


  2Na (s) + 0.5O2 (g) ---> Na2O (s)
• What is the enthalpy of combustion?


  The enthalpy change when one mole of a substance burns completely in oxygen with all substances in their standard states under standard conditions.
• Is the enthalpy of combustion exothermic or endothermic?


  Exothermic
• What is the symbol for enthalpy of combustion?

  
• What is the equation for the enthalpy of combustion for hydrogen?


  H2 (g) + 0.5O2 (g) ---> H20 (l)
• What is ionisation energy?


  Enthalpy change required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous ions with a +1 charge.
• What is the ionisation energy symbol?


  IE instead of I

  
• Is ionisation energy exothermic or endothermic?


  Endothermic
• Write the 1st and 2nd ionisation energy for magnesium.


  Mg (g) ---> Mg^+ (g) + e^-

  Mg^+ (g) ---> Mg^2+ (g) + e ^-
• What is electron affinity?


  The enthalpy change when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a -1 charge.
• Is electron affinity endothermic or exothermic?


  The first electron affinity is exothermic.

  The second electron affinity is endothermic because it is difficult to add a negatively charged electron to a negatively charged ion as like charges repel.
• What is the electron affinity symbol?

  
• Write the 1st and 2nd electron affinity equation for oxygen.


  O (g) + e^- ---> O^- (g)

  O^- (g) + e^- ---> O^2- (g)
• What is the enthalpy of atomisation?


  The enthalpy change when one mole of a gaseous atom is formed from the element in its standard state.
• What is the symbol for the enthalpy of atomisation?

  
• Is enthalpy of atomisation exothermic or endothermic?


  Endothermic
• Write the enthalpy of atomisation equation for iodine.


  0.5I^2 (s) ---> I (g)
• What is the enthalpy of hydration?


  The enthalpy change when one mole of gaseous ions is dissolved in water to form one mole of aqueous ions under standard conditions
• What is the symbol for enthalpy of hydration?

  
• Is enthalpy of hydration exothermic or endothermic?


  Exothermic
• Write the enthalpy of hydration equation for magnesium ions.


  Mg^2+ (g) + aq ---> Mg^2+ (aq)
• What is the enthalpy of solution?


  Enthalpy change when one mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are well separated and do not interact with each other
• What is the symbol for enthalpy of solution?

  
• Is enthalpy of solution endothermic or exothermic?


  Varies
• Write the enthalpy of solution equation for magnesium chloride.


  MgCl^2 (s) + aq ---> Mg^2+ (aq) + 2Cl^- (aq)
• What is the lattice enthalpy of formation?


  Enthalpy change when one mole of a solid ionic compound is formed from its constituent ions in the gas phase.
• What is the symbol for the lattice enthalpy of formation?


  Instead of LE it is LEF

  
• Is the lattice enthalpy of formation endothermic or exothermic?


  Exothermic
• Write the equation for the enthalpy of formation for magnesium chloride.


  Mg^2+ (g) + 2Cl^- (g) ---> MgCl^2 (s)
• How do the lattice enthalpy of formation relate to the lattice enthalpy of dissociation?


  They're the opposite of each other. Lattice enthalpy of formation equation backwards is the lattice enthalpy of dissociation equation.
• What is the lattice enthalpy of dissociation?


  Enthalpy change when one mole of a solid ionic compound is broken up into its constituent ions in the gas phase
• What is the symbol for the lattice enthalpy of dissociation?


  Instead of LAT it is LED

  
• Is the lattice enthalpy of dissociation exothermic or endothermic?


  Endothermic
• Write the lattice enthalpy of dissociation equation for magnesium chloride.


  MgCl^2 (s) ---> Mg^2+ (g) + 2Cl^- (g)
• What is bond enthalpy?


  The enthalpy change when one mole of covalent bonds is broken into two gaseous atoms
• What is bond enthalpy also known as?


  Bond dissociation enthalpy
• Is bond enthalpy exothermic or endothermic?


  Endothermic