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    doing an investigation using saturated potassium peroxodisulphate solution at the moment. my teacher told me before the investigation that the solution would go off.

    I prepared it on the 7th and tested it out on the 11th and it worked as required. I was away for a week and a half so I tested it again on the 25th and it worked again. so how long does it take for it to go off? also how long does it take for starch solution to go off?

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    It depends on the concentration you used, obviously if it is of ridiculously high concentration, it'd take a lot of reagents(of low concentrations) to titrate against it.
    , and a long time too, therefore.

    Hence, my suggestion is use sensible concentration, you would want a reaction that is within few minutes time, so you don't have to wait too long for reactions to happen.
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    (Original post by shengoc)
    It depends on the concentration you used, obviously if it is of ridiculously high concentration, it'd take a lot of reagents(of low concentrations) to titrate against it.
    , and a long time too, therefore.

    Hence, my suggestion is use sensible concentration, you would want a reaction that is within few minutes time, so you don't have to wait too long for reactions to happen.
    i didn't mean go off in that sense. i meant go out of date/expire/stop working normally.
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    (Original post by Dado Prso)
    i didn't mean go off in that sense. i meant go out of date/expire/stop working normally.
    ooh, i see!
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    (Original post by shengoc)
    ooh, i see!
    don't suppose you have an answer?
 
 
 
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