15 Born Haber Flashcards
What is Lattice Enthalphy?
relates to the formation of gaseous ions from one mole of a solid crystal breaking into gaseous ions
What is atomization enthalphy?
one mole of gaseous atoms is formed from the element in its standard state.
Example Equation for lattice enthalpy
∆Hlat⊖(NaCl) = ∆Hatom⊖(Na) + ∆Hi ⊖(Na) + ½E(Cl––Cl) + ∆He⊖(Cl) – ∆Hf⊖(NaCl
How would the Born Haber cycle differ when working with a group 2 metal and chloride?
the bond breaking energy for Cl2 would not need to be halved as the ionic compound would have 2 Cl
What does the ionic model assume in theoretical lattice enthalpies?
the only interaction is due to electrostatic forces between the ions
What does the energy needed to separate an ion depend on in theoretical lattice enthalpy ionic model?
charge & ionic radii
In an ionic model, what does an increase in ionic radius of one of the ions do ?
decreases the attraction between the ions
In an ionic model, what does an increase in ionic charge do?
increases the ionic attraction between the ions
General expression of Lattice enthalpy (memorize)
∆Hlat⊖ = [knm/ R1 + R2]
nm= charges
R= atomic radius
k= constant (ignore)
what is the enthalpy change of solution?
when one mole of solute is dissolved in a solvent to infinite dilution under standard conditions
What is hydration enthaly?
when one mole of constituent gaseous ions is dissolved to form an infinitely dilute solution
Why does hydration enthalpy decrease down a group?
as the ionic radius increases the electrostatic force between the ion and the water molecule decreases
Why does the hydration enthalpy increases across a period?
charge increase and radius gets smaller
Formula for hydration enthalpy (memo)
∆Hhyd⊖ ≈ (-Bn/ R)
B= constant
n=charge
R= radius
Formula for enthalpy change of solution
∆H⊖sol (NaCl) = ∆H⊖lattice(NaCl) + ∆H⊖hyd(Na+) + ∆H⊖hyd(Cl−
