Lattice Energy of aluminium oxide, Born harber cycle

Hi i have a problem and i would be grateful if some one helped me out here... thanks

Calculate the lattice energy of Al2 03. Show a full born harber cycle on how you worked out the lattice energy.

Al2 03 = alminium oxide by the way ... thanks .. i need this before tommorow though lol.. so please reply asap

Reply 1

shengoc

12

Soppe

Hi i have a problem and i would be grateful if some one helped me out here... thanks

Calculate the lattice energy of Al2 03. Show a full born harber cycle on how you worked out the lattice energy.

Al2 03 = alminium oxide by the way ... thanks .. i need this before tommorow though lol.. so please reply asap

Do you know what a born haber cycle is first of all? If you don't, i suggest some reading, and then you try simple example, then attempt this question, then if you are still stuck, come plead for help. If you don't try, how would you know how? If you have born haber cycle, how come you can't draw one and then people can point out where you have gone wrong? You simply haven't tried.

Reply 2

shadow12345

OP

3

Erm yeh .. i have read the book and tried several examples .. but failed some of the times
i can do one when its a Na + CL .. but i cant do al2 03 ..

Reply 3

charco

Study Forum Helper

18

Soppe

Erm yeh .. i have read the book and tried several examples .. but failed some of the times
i can do one when its a Na + CL .. but i cant do al2 03 ..

so follow the same steps you used for NaCl with the following variations in mind...

1. You need two atoms of Al to turn into gaseous atoms
2. Al forms a 3+ ion so you need three ionisation energies for each atom

3. you must atomise enough oxygen to get 3 oxygen atoms
4. you must use two electron affinities on every oxygen atom to get three oxide ions

Reply 4

shengoc

12

Soppe

Erm yeh .. i have read the book and tried several examples .. but failed some of the times
i can do one when its a Na + CL .. but i cant do al2 03 ..

http://www.chem.purdue.edu/chemsafety/Equip/Al2O3LatticeEnergy.htm

see if this help.

Reply 5

shadow12345

OP

3

Well i asked a little help, and ive got to the finishing point . but i just want to make sure that the answer that i found is right ... Is the lattice energy of Alminium oxide around 15 000 kj per mole?

Reply 6

charco

Study Forum Helper

18

Soppe

Well i asked a little help, and ive got to the finishing point . but i just want to make sure that the answer that i found is right ... Is the lattice energy of Alminium oxide around 15 000 kj per mole?

google it (but check your spelling first)

Reply 7

abli1518

i dont know if i am late.
The lattice energy that u hv calculated is approx right(-15291.40 K Joules /mol to be exact ) but with a negative sign (Lattice energy and First electron affinity is always exothermic i-e negative)

Reply 8

charco

Study Forum Helper

18

Original post by abli1518

i dont know if i am late.
The lattice energy that u hv calculated is approx right(-15291.40 K Joules /mol to be exact ) but with a negative sign (Lattice energy and First electron affinity is always exothermic i-e negative)