http://lessons.chemistnate.com/uploads/5/0/2/9/5029141/__4177903.png?223

 

I'm having trouble understanding how the 4th line is derived from the 3rd line, would anyone mind explaining to me?

 

I understand how the RHS (right hand side) is merely being simplified, but why exactly does it become -1 over T₁ and T₂? To make -delta H_vap positive, would be the simple answer I suppose, but why does it work?

 

In other words could you point out the rules in maths for this kind of rearranging?

 

Thanks!

 

 

In line four if you multiply deltaH /R into both terms in the bracket, you recover line 3 and remove the bracket.

 

All they have done is the equivalent of {-3/2a - 3/2b} take out the common terms 3/2 leaves 3/2{-1/a - 1/b}

 

can you see it now it is simple algebra.

 

Sorry I can't do the latex at the moment.

Very well explained, yes I can see that now, cheers mate.