H2O (aq)) SO2 (g) this would show that step 1 is the rate determining step cuz its the slowest step due to the sodium thiosulphate being decomposed and it also shows that: SO32-(aq) HSO3-(aq) H (aq) would be cancelled out so they are reaction intermediates, but does that mean that the concentration of H wouldn't have any affect on the reaction, because i have it as first order I try to explain the order of reaction more like a relay race.
Oh and remember - frequency of collisions isn't the only factor to affect the rate of reaction, temperature is important.
Molecules can collide as many times as they want, but if they don't have the correct activation energy to react they're not going to.
Increasing the concentration of sodium thiosulphate will increase the rate of reaction because you’re going to have more particles at the correct activation energy: e.g.
lets say you have 1000 thio molecules and 5% are at the correct activation energy, 50 are going to have the right activation energy to decompose.
Therefore the slowest runner (the slowest step in the reaction mechanism) will limit (hence the term "rate limiting step") the speed that the whole relay team can run.
No matter how fast the other runners are, they have to wait for the slow one and so it limits the overall speed and thus determines it, since most intermediate steps happen nearly instantaneously.
The slow step above involving the thio only is what's holding up the reaction. If you keep increasing the speed in the fast lane, cars are going to move so you don't get traffic build-up.
It’s at this point where the reaction becomes zero order with respect to HCl; you can keep increasing the concentration of HCl but since it's not involved in the r.d.s. But if it's the slow lane that's causing most of the traffic, there comes a point where the increasing the speed in the fast lane won't make a difference to the traffic because there is no traffic there. The second part of my investigation is looking at the catalytic effect on the reaction I found that Iron (II) ammonium sulphate acted as a catalyst, increasing the rate of the reaction However iron (II) sulphate had no effect on the reaction It seams to me that the ammonia is having an effect, but cant explain how/why. It is a homogeneous catalyst as the catalyst is in the same physical state as the reactants.
The reaction is going to be affected by how fast this decomposition takes place.
Increasing the amount of HCl won't affect this step because HCl isn't involved in it.