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Chemistry help - rates of reaction

HERE IS WHAT I'M DOING: I believe that as the temperature of the reacting solutions is increased, the rate of reaction also increases.


MY EXPERIMENT: rates of reaction temperature experiment between HCl acid and sodium thiosulphate. If you need more info to understand: (http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_nos_ps_8.pdf).


MY QUESTION: Describe briefly how you would carry out a preliminary investigation to find a suitable value to use for this variable. Explain how the results will help you decide on the best value for the variable.


MY SECOND QUESTION:Why might you carry out a preliminary investigation?
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Pigster
20
What is the lowest temp you can use? Too low and it'll freeze / take too long to react, so you'd try it at 10 oC and see what happens. You don't have to do it too carefully e.g. volumes don't have to be perfect, you're just trying to get a feel for it.

What is the highest temp you can use? Too high and it'll start to boil (dangerous with acids) or react too fast (and produce a lot of nasty gas quickly). Again, pick a number, e.g. 60oC and try it. If the slowest and quickest give you a nice spread of results, you can sub-divide it to investigate over that range. If one of the two is a bad choice, choose another value and try that.

You carry out prelim. expts. to find out: will your planned method even work? do you have the l33t skillz to carry it out? Is it safe? How long will one reaction take (and hence can you get a full set of results in the time you have)? What is the smallest and largest independent variable values you should use?

You could also start to consider whether you can get repeatable results.

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