[Mitch]

If a reaction requires 240kJ/mol how can one determine what temperature to set an over or a hot-plate or any themo-component to ensure that the neccessary amout of energy gets pumped into the system?

[mike]

Do we need to know more than just the activation energy?

[Mitch]

Actually that wasn't even the H_activation, that was only the bond dissociation energy for the following reaction.

Cl2 --> Cl + Cl  H=240kJ/mol   

The heat of activation would be more appropriate, still is there any back of the envelope method for determining what temperature to set an oven at to ensure the reaction takes place?

[mike]

I thought this was determined experimentaly but I am not sure Increasing the temperature will increase the rate (as I am sure you know) But I am not sure that determining the temperature of the oven will translate directly into enthalpy. Maybe you could estimate knowing the specific heat and mass of sample? I would think that you would also have to account for decomposition temperatures, equipment limitations, required reaction time etc etc

Sorry I haven't been much help.

[Mitch]

It makes more sense just talking to someone about it.

Yeah, increasing the temperature will increase the rate.

It's very tempting to go down the following path of logic: If you had a mol of Chlorine and you had an oven that was working at 1500Watts or 1500 J/sec, and you could remove the Cl radical selectively from the system, I would suppose in 160seconds would be all that is necessary to completely convert Chlorine gas into chlorine radicals assuming that this process was 100% efficient and the radicals don't reform to give Cl2.

I'm usually very clever in distinguishing between kinetics and equilibrium effects. But, I find myself having a harder and harder time with these fundamental principles as my qualifying exam approaches nearer and nearer.

[Borek]

I find myself having a harder and harder time with these fundamental principles as my qualifying exam approaches nearer and nearer.

It is called panic

[Mitch]

Thanks Borek.