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February 21, 2026, 07:52:55 pm
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Author Topic: Titration question...  (Read 1063 times)  Share 

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nerd

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Titration question...
« on: March 13, 2009, 07:18:58 pm »
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This question is referring to the Prac on page 51 of the Heinemann Student workbook. Sorry if you dont have it...

Explain the effect on the calculated concentration of nitrogen if the water was found to have a pH of 6. Would it cause the conc of nitrogen to be higher, lower or no effect?
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pHysiX

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Re: Titration question...
« Reply #1 on: March 15, 2009, 11:21:24 am »
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haha...i did that prac. for your question..well i'm no chem genius but here's my guess:

pH6 is slightly acidic yea? so that would mean that the NaOH added will not only with the NH4+, but will also neutralise the water. Hence, there will be less excess NaOH and in your final calculations, this would suggest a "higher amount" of NH4+ when it's actually the water that's also reacted with the NaOH.

So the concentration of N would be higher than expected. Please correct me if I'm wrong. =]
« Last Edit: March 15, 2009, 11:24:15 am by pHysiX »
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nerd

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Re: Titration question...
« Reply #2 on: March 15, 2009, 01:04:30 pm »
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Awesome...that sounds right. Also, why is it necesssary to do a back titration in this experiment?
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TrueTears

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Re: Titration question...
« Reply #3 on: March 15, 2009, 01:16:15 pm »
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This is because the ions is too weak an acid to give a sharp end point in direct titrations. Therefore a back titration is needed to give a more accurate result.
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