graphite to diamond - exothermic, endothermic or neither?

[the guy]

is the formation of diamond from graphite (under extreme heat and pressure) exothermic, endothermic or neither?

 

also, while we're at it, is there a way of telling whether a reaction will be exothermic or endothermic?

 

hang on, i think this is in the wrong place, how do you move it?

[Mr Skeptic]

Look up the enthalpy of formation, and compare.

[Horza2002]

Exo essentially means leaving

 

Endo essentially means receiving

 

Thermic refers to heat

 

So, exothermic means heat leaves the reaction (and will therefore fell hot) while endothermic heat enters the reaction (and will therefore feel cold).

 

As Mr Skeptic has said, the enthalpy will tell you whether a reaction is exo or endo.

 

In general, reactions that are neither exo or endothermic tend to be isomerisations.

[mississippichem]

Just total up the [ce] \Delta H^o [/ce] values for each step of the reaction, breaking lattices, breaking bonds, forming bonds, phase changes... then see if your total value is positive of negative. Remember to account for stoichiometry if your heat values are expressed as molar quantities.

 

If you look up Born-Haber cycles, you'll even learn that every route from A to B, no matter which route you use takes the same amount of heat when all is said and done.