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man0005
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Homework Statement
Just need someone to confirm whether I am right for this
(The prac is using back titration to find the amount of Nitrogen in Fertiliser)
How would the following affect your experiment:
Burette, pipette and volumetric flask are rinsed with the wrong solution i.e water
Burette - HCl will be diluted, thus it will appear that more will be needed to achieve equivalence point. This will mean that you will get a smaller amount for the NaOH reacting initially and subsequently the amount of NH4+. This will mean that you will have an overestimation of the amount of Nitrogen.
Pipette - NaOH will be diluted, thus it will appear that less HCl will be needed to achieve equivalence point. This will mean that you will get a larger amount for the NaOH reacting initially and subsequently the amount of NH4+. This will mean that you will have an underestimation of the amount of Nitrogen.
Volumetric Flask - No effect as the mass of the fertilizer as been weighed already, so the concentration will be same when you measure out 250mL. The water is used to dissolve the fertilizer sample anyway.
Conical Flask - No effect. Fixed number of moles in NaOH therefore even when diluted it will not affect end titration, since titration only involves moles. Fertiliser standard solution has already been diluted by water so will not be affected either.