[missbrokensmile]

I'm really confused about the data processing I have to do for an experiment. I'm hoping someone can *delete me*

What I'm ultimately trying to do is find the rate: rate=concentration/time

My experiment is the iodine clock reaction (hydrogen peroxide variation) and I'm investigating the relationship between temperature and reaction rate.

But to find the reaction rate, I need to find concentration and I'm confused about how to go about finding this concentration.

The equation of the reaction is:
2I- (aq) + H2O2 (l) + 2H+ (aq) --> I2 (g) + 2H2O (l)
I2 (g) + 2S2O3-2 (aq) --> S4O62- (aq) + 2I- (aq)
[is there a third reaction with the colour change? would that be signficant in what I'm trying to calculate?]

The chemicals I used are:
Distilled water
3% Hydrogen peroxide (H2O2)
Potassium iodide (KI)
Sodium thiosulfate (NaS2O3)
Soluble starch (freshly prepared)
Sulfuric acid (2.5M)

My question is, which one am I supposed to use to figure out the concentration? The products/rectants? The actual chemicals used or equation of reaction? Do I add all the chemicals/ions used and use a single concentration? And how exactly should I calculate the concentration?

I'd appreciate any sort of *delete me*

[Borek]

Is it all? Or perhaps you did some measurements during the experiment?

[missbrokensmile]

Well, I mixed up a "solution A" (made up from Distilled water, Potassium iodide (KI), Sodium thiosulfate (NaS2O3), Soluble starch, Sulfuric acid (2.5M)) and a "solution B" (made from hydrogen peroxide and distilled water). And I basically used them as stock solutions (not sure if that is the right word) for each repeat/temperature change.

Basically, I poured a small amount of solution A and B together in a conical flask and timed the time taken for the colour to occur.

In the experiment, I recorded the time taken for the dark blue colour to appear. So the only measurements I have are time (plus temperature and I could *possibly* calculate moles or whatever)

Independent: Temperature
Dependent: Time taken for the colour to occur

[Borek]

I poured a small amount of solution A and B together in a conical flask

Random volume, or have you measured the volume taken?

[missbrokensmile]

I measured it

[missbrokensmile]

Sorry, I mixed up solution A. The potassium iodide is supposed to be in solution B

[Borek]

So, if you have measured volume, can you calculate number of moles of substances that were present in the measured volume?

[missbrokensmile]

I can calculate the moles. But, how do I calculate concentration? As in, which part of the equation/chemicals do I use?

[Borek]

You know moles then.

Can you calculate volume of the mixture?

[missbrokensmile]

I can.

[Borek]

So you know number of moles, you know the volume, can you calculate concentration?

[missbrokensmile]

I know that to calculate concentration, it's: c=n/v, but I don't what parts of the chemicals to calculate concentration from. Do I calculate a single chemical, ie. sodium thiosultfate, or do I calculate all the products/reactants, and I also don't understand how the experimental concentration is supposed to fit into the half equation of the equations of the clock reaction

[Borek]

Each substance separately.

I also don't understand how the experimental concentration is supposed to fit into the half equation of the equations of the clock reaction

No idea what you mean, please elaborate.