iron content in fertiliser prac questoins

[Greatness]

How could the results obtained be affected if the fertiliser contained other chemicals that can be oxidised by permaganate ions?

Thanks

[bar0029]

less volume of potassium permanganate would be required
because for every mL (or such) it is being reduced by the Fe2+ alongside the other substance
therefore, the colour change will occur sooner then if it were just the FE2+
resulting in an underestimate of the volume of KMNO4


I THINK..

[Greatness]

less volume of potassium permanganate would be required
because for every mL (or such) it is being reduced by the Fe2+ alongside the other substance
therefore, the colour change will occur sooner then if it were just the FE2+
resulting in an underestimate of the volume of KMNO4


I THINK..

Hmm this what i thought as well, can anyone else confirm?

[huaxiadragon]

less volume of potassium permanganate would be required
because for every mL (or such) it is being reduced by the Fe2+ alongside the other substance
therefore, the colour change will occur sooner then if it were just the FE2+
resulting in an underestimate of the volume of KMNO4


I THINK..

Hmm this what i thought as well, can anyone else confirm?

Yes the colour change WILL occur sooner if there's ONLY Fe2+

However, if there's ONLY Fe2+, then the permanganate consumed will be less than the case where we have "other substances".

The result I presume is the mass or mol of Iron in the fertiliser. If there is other substances, they will reduce permanganate and the permanganate titre will be HIGHER than having ONLY Iron as the reductant. Therefore an overestimation of Iron mass will result.

I agree with bar0029, but the way SHE explained is a bit confusing to me, so I'll just clarify

[bar0029]

BAR0029 IS A GIRL hahahahaa

[huaxiadragon]

BAR0029 IS A GIRL hahahahaa

Of course I knew that, check out my post. It totally said SHE

xD

[Greatness]

Do we refer to the point at which a spontaneous change of colour occurs as a end point or equivalence point in a redox reaction?

[Water]

My teacher said, we'd use the end point, because the equivalence point is near to the end point.

Unless there's a method to find equivalence point, cause as far as I'm concerned, isn't the definition of it when they just become stoic ratios to one another.

[Greatness]

This is the situation:
We got 0.35% of iron, however, the expected result was 0.30%.
Would adding too much potassium permanganate be a factor in the increased %?
Any other reasons?

[Water]

-Adding more permanganate because of other substances that can be oxidized would be a factor.

- Other factors could include systematic errors, like burette, pipette, conical flask.

-This happened in our school, the standard concentration of permanganate is not correct, hence requires more titre.

- During the actual titration, you go over the amount slightly (random error?), hence the slightly increase in irons.

[Greatness]

Cool thanks heaps!