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Topic: Acidified Fe2+solution is titrated with permanganate solution  (Read 1672 times)

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Offline Namossa

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Acidified Fe2+solution is titrated with permanganate solution
« on: August 29, 2018, 02:26:42 PM »
Hi I have a question concerning this?

An acidified Fe2+ solution was titrated with permanganate solution. When titrated went 20 cm^3 0.02020 mol/dm^3 MnO4 solution. Determine the amount Iron expressed in gram in the first solution?

Here are my calculations
5Fe2+ (aq) + MnO4- (aq) + 8H+ --> 5Fe3+ (aq)+ Mn2+ + 4H2O

Fe Molar mass 55,935 g/mol

n=c * (V/1000)

0.02020 * (20/1000) 4*10^-4

Ratio MnO4: Fe2+
1:5

4* 10^-4 * 5 =2,02 *10^-3

2,02 *10^-3* 55,935= 0.1129887 g

The correct answer is 0.01127g

What I am doing wrong
please help
Thank you!


Offline chenbeier

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Re: Acidified Fe2+solution is titrated with permanganate solution
« Reply #1 on: August 29, 2018, 02:45:20 PM »
Quote
Determine the amount Iron expressed in gram in the first solution?

What does it mean. Your calculation for the 20 cm³ is correct, but was this sample taken from something ?

Offline Namossa

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Re: Acidified Fe2+solution is titrated with permanganate solution
« Reply #2 on: August 29, 2018, 03:33:50 PM »
It was not written in the question.

Any more comments?

Thanks!

Offline chenbeier

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Re: Acidified Fe2+solution is titrated with permanganate solution
« Reply #3 on: August 29, 2018, 03:48:29 PM »
Then it can be  only 2 cm³ solution or it was 0,00202 mol/l concentration.

Offline Namossa

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Re: Acidified Fe2+solution is titrated with permanganate solution
« Reply #4 on: August 29, 2018, 04:06:41 PM »
I solved it thx!

Offline chenbeier

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Re: Acidified Fe2+solution is titrated with permanganate solution
« Reply #5 on: August 29, 2018, 04:11:14 PM »
What was the reason now?

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