Chemical Forums

Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: Imrahil on January 26, 2005, 10:43:49 PM

Title: Lattice Enthalpy (anyone know how?)
Post by: Imrahil on January 26, 2005, 10:43:49 PM

I dont know how to calculate lattice enthalpies. One question which I cant do is this one. If you know how to do it, can you please explain it when you give the answer, thanks.

Calculate the lattice enthalpy of calcium bromide. Here is some information to help you complete this calculation:
    enthalpy of formation of CaBr2:                     – 683 kJ/mole
    bond enthalpy of Br2(g):                                   112 kJ/mole

    electron-gain enthalpy for Br(g):                    – 325 kJ/mol

 

Answer = 2089 kJ/mol

Title: Re:Lattice Enthalpy (anyone know how?)
Post by: Mitch on January 26, 2005, 10:55:56 PM

Quote

....explain it when you give the answer

We don't give answers, we help you solve problems. Why don't you tell us how you think you should begin, and we'll help from there.

Title: Re:Lattice Enthalpy (anyone know how?)
Post by: maxyoung on February 02, 2005, 09:03:41 AM

To calculate the lattice energy of CaBr2, you can use a Born-Haber cycle, but you need three more data besides those given in the question--the atomization energy of calcium, the first ionization energy of calcium and the second ionization energy of calcium. I suppose it has been missed somewhere.