Lab Report Rate of reaction for the Briggs Rausher reaction

[sanfonts]

Hello! I think you might be familiar with the Briggs-Rauscher reaction, where you mix 3 solutions and then they do oscillate between colorless-yellow-dark blue for a couple of minutes.

I thought this kind of reaction would be quite useful for measuring the effects of temperature over the duration of the oscillations, because we were supposed to investigate a factor that might had an effect over kinetics.

Right after you mix the solutions, they turn into a yellow color, then blue, clear, yellow, blue...

So I decided to measure the time it takes for the solution to undergo the cycle blue-clear-yellow, and I restarted the chronometer the moment the solution turned into blue again.

So, let's say that for 20°C, I got the next data for the duration of one cycle: 13.09, 12.68, 12.15, 11.77, 11.5 and so on, averaging 12.24 seconds.

My teacher said it was ok to calculate the rate of reaction only with the "general" reaction that acounts for one oscillation, that is to be said:

IO3- + 2 H2O2 + CH2(CO2H)2 + H+ --> ICH(CO2H)2 + 2 O2 + 3 H2O

If I know that the nominal concentrations of the reactants where:

0.050M for CH2(CO2H)2

0.067M IO3-

0.038M H2SO4

1.3M H2O2

0.0067M MN2+

Can I just assume that the overall rate of reaction was 1/(12.24) = 0.08170?

I wasn't told until a few days ago we were supposed to calculate rates of reaction (I thought comparing just the seconds would be more than enough), and I truly don't know how to calculate them. Could you please help me?

Thank you in advance,

[Drake Glau]

Rates are the change in concentration per unit time.

With all those concentrations you can have there you can find out how much of the stuff (i dont feel like writing it out) you make in that one reaction (one color change? I actually don't know this reaction but it sounds so cool). So if you can find out how much of the stuff you are making (find limiting reactant, find how much mass of the limiting reactant was used, mole to mole ratio, voila) and then figure the concentration which is number of moles/volume (dm^3) and then you will have your concentration of product formed and also the amount of time it took. [P]/t=Rate

And you have:

0.038M H2SO4

0.0067M MN2+

In there as well? It might just be me not knowing the reaction but those aren't in the equation you posted

Edited December 17, 2010 by Drake

[sanfonts]

Hello! Thank you for your idea, I didn't have even the slightest idea about where to start. It looks like H2SO4 and MN2+ act as catalysts that allow the reaction to happen, so I guess they shouldn't be that important for the reaction itself...

This is the Briggs Rauscher reaction:

, it has some nice explanations.

Rates are the change in concentration per unit time.

With all those concentrations you can have there you can find out how much of the stuff (i dont feel like writing it out) you make in that one reaction (one color change? I actually don't know this reaction but it sounds so cool). So if you can find out how much of the stuff you are making (find limiting reactant, find how much mass of the limiting reactant was used, mole to mole ratio, voila) and then figure the concentration which is number of moles/volume (dm^3) and then you will have your concentration of product formed and also the amount of time it took. [P]/t=Rate

And you have:

0.038M H2SO4

0.0067M MN2+

In there as well? It might just be me not knowing the reaction but those aren't in the equation you posted

[Drake Glau]

IO3- + 2 H2O2 + CH2(CO2H)2 + H+ --> ICH(CO2H)2 + 2 O2 + 3 H2O

If I know that the nominal concentrations of the reactants where:

0.050M for CH2(CO2H)2

0.067M IO3-

1.3M H2O2

Hmm I failed my earlier post...you have the concentration already so the whole finding concentration thing was me randomly switching your numbers to moles for no reason...

It's a 1:1 mole ratio of CH2(CO2H)2 to ICH(CO2H)2 so in one cycle of colors or one color change (I don't know whether the full cycle is a full reaction or if just one color change is o.O) you should make 0.050M and then rate is just [P]/t which would be 0.050/time and that should give you your rate.

Edited December 17, 2010 by Drake

[catlover101]

idk how to do this either, and im doing the briggs rauscher reaction for my IA too. someone help me