Abu Muhammad, on 03 June 2010 - 01:02 AM, said:
With the following reaction, why is it physically impossible for it to occur under low pressures?
F + NO2 --> NO2F
For any reaction to occur the molecules present have to collide with energies equal to or greater than the activation energy for that particular reaction. Activation energy is the minimum energy required before a reaction can take place.
So two things here, 1) Collision (orientation also matters) 2) At the right energy
The reaction you put above is in the gas phase i.e. all the reactants are gases.
Take a high pressure scenario, lots of those molecules present in the reaciton vessel, or a given space, lots of molecules to collide against the sides of the vessel which generates even more pressure, the molecules go shooting off in all directions increasing the likelihood of reaction happening.
If for example the reactants were just floating around in the air, (there was no vessel say?), then pressure would be very low ..how exactly will the two above mentioned criteria ever be fulfilled and the reaction take place under such low pressure?