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    It says,
    If more than 5 cm3 of DCPIP are completely decolourised, dilute the fruit juice and repeat the test.

    Why's that?
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    I assume because if you are trying to estimate the concentration of vitamin C and compare it to other juices, after a specific concentration it will completely discolourise DCPIP. Meaning that you can't distinguish between concentration of different juices. For example if 5mol/ml vitamin C discolourises DCPIP, so will 7, 10 or 1000mol/ml. It is simply to be able to tell between these that you have to dilute. I would say that if you are comparing and you only have 1 juice completely discolourising DCPIP then there would be no need to, unless you are measuring specific concentration using spectrophotometry or something.
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    (Original post by alkyone)
    I assume because if you are trying to estimate the concentration of vitamin C and compare it to other juices, after a specific concentration it will completely discolourise DCPIP. Meaning that you can't distinguish between concentration of different juices. For example if 5mol/ml vitamin C discolourises DCPIP, so will 7, 10 or 1000mol/ml. It is simply to be able to tell between these that you have to dilute. I would say that if you are comparing and you only have 1 juice completely discolourising DCPIP then there would be no need to, unless you are measuring specific concentration using spectrophotometry or something.
    I see! Thaanks!!
 
 
 
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