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Rate Equation For Uncatalysed Experiment

How do you do this? I've missed so much Chemistry, and I'm asked to do this in my coursework. I have no idea what I'm doing :frown:

Thanks

Reply 1

Organ

You can't just make one up theoretically - the rate equation needs to be derived from the experimental data....

Reply 2

Failed123

Original post by Organ

You can't just make one up theoretically - the rate equation needs to be derived from the experimental data....

What data do I need? I have it... I've done graphs and stuff :confused:

Reply 3

yousif92

Original post by Failed123

How do you do this? I've missed so much Chemistry, and I'm asked to do this in my coursework. I have no idea what I'm doing :frown:

Thanks

First, what is the experiment??

Reply 4

Failed123

Original post by yousif92

First, what is the experiment??

It's the Iodine clock one, where you vary the concentrations of the Potassium iodide and the peroxodisulphate.

Reply 5

yousif92

oh right. So did you take some of the reaction mix at particular times and titrate?

Reply 6

Keckers

I expect that from the graphs you have drawn you are able to deduce what order each reaction is?

Reply 7

Failed123

Original post by yousif92

oh right. So did you take some of the reaction mix at particular times and titrate?

Yeah, I did one experiement where I varied the concentration of the Potassium Iodide and measured the time it took for the mixture to turn blue-black. I also did the same in a different experiment with the Peroxodisulphate... and then I did temperature, catalyst etc.

:frown:

Reply 8

Failed123

Original post by Keckers

I expect that from the graphs you have drawn you are able to deduce what order each reaction is?

Yeah, the first ones are first order... with the concentration.

Reply 9

Keckers

Original post by Failed123

Yeah, the first ones are first order... with the concentration.

Ok, so what equations do you know that tie the order of the reaction with the rate?

Reply 10

Failed123

Original post by Keckers

Ok, so what equations do you know that tie the order of the reaction with the rate?

I don't know, I'm only basing this on the line of my graph :confused:

I fail...

Reply 11

gingerbreadman85

rate=k[A]^x^y

where k is the rate constant (k=Ae^-Ea/RT)

If the reactant is first order, the graph of concentration vs rate will be a directly proportional line, if zero order it'll be flat, if greater than 2nd order it'll be a curve.

Reply 12

yousif92

Right pal, if you could stick up a plan of your experiment and explain step by step what was carried out, then we could help. But based upon what we know, you have a known conc of [KI]. Im assuming that you are reacting it to get some sort of substitution so you can get your I2 (blue/black). You are measuring the time for the reaction to complete. So from this, if you draw a graph of conc on the y axis and time on the x, then you can determine its order... But you are going to need to expand a little man...