# Chemistry

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I had to perform an experiment for rate of reaction.

The point of the experiment was to show how changes in reactant concentration, temperature, and catalyst presence can affect the rate of a reaction. The reaction that we studied was
H2O2 + 2I^- + 2H^+ -> I2 + 2H2O

We had to set up 6 flasks each with and certain amount of KI, starch, DI water, buffer, acid, Na2S2O3, and H2O2 all in mL. Then we had to measure the time it took for a reaction to happen which was indictated when the solution began to turn blue. For Na2S2O3 each flask had 2.50mL in it which is a total of 15.

I have to calculate the concentration of Na2S2O3 in the reaction solutions based on the volume used in each reaction flask and the total volume calculated.

I hope I explained this better this time.

Chemistry - L.Bianchessi, Sunday, February 26, 2012 at 12:41am
I did this same experiment a couple weeks ago. We are measuring the amount of time it takes for the thiosulfate to run out.
So to calculate the concentration of the thiosulfate ion. You can multiply the milliliters of thiosulfate in whatever trail you are calculating it for by the concentration of the thiosulfate divided by the total volume in milliliters of all the KI, dionizedwater, buffer etc. Which mine was 150ml but yours is probably different. That should give you your concentration. You could use the same process to find concentration of hydrogen peroxide and the others if needed in your data calc.
Does that help any?

Yes I think that helps me. Im not very good at this stuff so let me make sure I understand this.

The concentration of the thiosulfate used was 0.10M and for each flask we used 2.50mL. So I have to multiply these two (2.50mL)(0.10M) and then divide by the total amount combined for all the other solutions used, is that correct?

• Chemistry - ,

It says that the final volume for every reaction solution is 75mL so is that what I divide by?