[mahiru]

I am investigating how different transition metal catalysts (with different charges) affect the rate of reaction between Sodium thiosulfate and Iron(III) Nitrate. My catalysts were Ag(I)NO3, Cu(II)SO4, and Fe(III)Cl3. I observed the reaction from above and recorded the time it took for the cross at the bottom of the reaction became visible.

first of all, since I am not changing concentration, how do I find rate of reaction?

Also, I am having a hard time understanding what is happening.
CuSO4 was fastest (average of about 10.83 sec for the cross to appear)despite it being +2., and the other two (+1 and +3) were about the same to each other (around 56seconds). I don't understand the pattern, and what is affecting this.
can someone explain why CuSO4 was a better catalyst and why the other two didn't show much difference to each other? I have no clue what is going on and how exactly the catalysts impacted the reation...

Please help me. Thank you in advance.

[Borek]

first of all, since I am not changing concentration, how do I find rate of reaction?

You can't. All you can do is to qualitatively state "this is faster, this is slower". For some applications this is perfectly enough though.

Also, I am having a hard time understanding what is happening.
CuSO4 was fastest (average of about 10.83 sec for the cross to appear)despite it being +2., and the other two (+1 and +3) were about the same to each other (around 56seconds). I don't understand the pattern, and what is affecting this.
can someone explain why CuSO4 was a better catalyst and why the other two didn't show much difference to each other? I have no clue what is going on and how exactly the catalysts impacted the reation...

You can't base the conclusion on a single run using just three metals. Way too many different factors.

Plus, using Fe(III) compound as a catalyst in the presence of the reacting Fe(III) compound sounds like a nonsense idea - you alrerady have an excess of the cation in the solution, no way to say if addition of a bit more produces catalytic effect.

[mahiru]

Thank you for the reply.

I found the rate.
No catalyst: 105.59 s , rate 0.00947 s-1

AgNO3 57.94 s, 0.0173 s-1

CuSO4 10.83 s, 0.0923 s-1

FeCl3 55.35s, 0.0181s-1

I used one drop of catalyst(0.01M) for each trial of 10ml Sodium Thiosulfate (0.1M) + 10ml Iron3Nitrate reaction(0.1M).

Using Fe(III) catalyst definitely was not a good idea and the problem is, I cannot do anymore experiments and can only write my paper based on what I have now at this point... 

I'm wondering if there is any factor between the three catalysts that I could compare and why they might result in the values I got.
I don't really mind the data I got and whether it worked or not anymore, but I want to understand what and why everything is happening...

[Corribus]

Protip: It's hard to interpret data without knowing exactly what you did. The rate is a measure of what, exactly?

Beyond that, I would regard the data for the reaction with iron to be fairly meaningless, since (as Borek noted) iron is also one of your reactants. The slightly faster rate may just be because there's more of it.

Based just on your numbers, it would appear that Cu > Ag > control. Ideally your counterion would be the same to ensure that isn't changing things, but I guess too late now.  Your value with Ag is pretty close to your control. Maybe it's significant but you haven't provided any statistical analysis so hard to know. So really what I've got is that maybe Ag is catalyzing your reaction a little, and Cu probably is.

These are just numbers, though. Hard to make any mechanistic conclusions from a few measured rates alone, much less without any information about what you did, what your balanced reaction is, and etc. Catalytic mechanisms are generally complicated and require lots of experiments to fully figure out, and it usually isn't obvious just by inspection why one metal is a good catalyst and another isn't - and it usually doesn't come down to "this is +2 and this is +1". You may consider searching the literature to better understand how copper catalyzes this reaction; then maybe you can say something about why Ag is less effective. This is generally the best approach to completing a laboratory write-up, just like science in the real world.