Experiment(Determining the reaction order)

[Lord Dark]

Homework Statement

Hi guys, Girls

Today we've done an experiment to determine the order of reaction of :

KMnO4 & Oxalic acid ,, I've got the following results :

EXP | KMnO4 | Oxalic Acid | Rate

Exp1: 3.3e-3 M 0.39 M 4.48e-3
Exp2: 3.3e-3 M 0.78 M 4.57e-3
Exp3: 6.6e-3 M 0.39 M 2.99e-3

I think there is something wrong with the rates because when I want to get the order of reaction of Oxalic acid I get (0.5)^m=1 ,, so m =0 and I don't think it's right because I think it has to react too,, can anyone tell me what's their order of reaction to know what did I do wrong please ,,

Thanks in advance

 

[epenguin]

We would need a bit more info about what your kind of experiment and obsrvations were. Preferably with figs. You quote units (M) for concentrations but not for rates. If those are Ms^-1 then the reaction is over in something like a second. Did you observe a rate over a period during which the reactant concentrations didn't change very much, which would be the simplest for interpretation?

On the face of it, when you doubled the OAA you scarcely changed the reaction rate - that would be zero order. When you doubled the KMnO₄ the reaction actually slowed. One could probably come up with a mechanistic conjecture, but it seems sufficiently unexpected people would want to look at the experiment and observations before trying!

 

[Lord Dark]

actually , the experiment was to measure the period that permanganate become yellow with different volumes of distilled water, potassium permanganate and oxalate acid.
and we got the time then get their invert so we get the rate ,, it's simple but the problem is getting the period right ~.~