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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Namossa on August 29, 2018, 02:26:42 PM

Title: Acidified Fe2+solution is titrated with permanganate solution
Post by: Namossa 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!

Title: Re: Acidified Fe2+solution is titrated with permanganate solution
Post by: chenbeier 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 ?

Title: Re: Acidified Fe2+solution is titrated with permanganate solution
Post by: Namossa on August 29, 2018, 03:33:50 PM

It was not written in the question.

Any more comments?

Thanks!

Title: Re: Acidified Fe2+solution is titrated with permanganate solution
Post by: chenbeier on August 29, 2018, 03:48:29 PM

Then it can be  only 2 cm³ solution or it was 0,00202 mol/l concentration.

Title: Re: Acidified Fe2+solution is titrated with permanganate solution
Post by: Namossa on August 29, 2018, 04:06:41 PM

I solved it thx!

Title: Re: Acidified Fe2+solution is titrated with permanganate solution
Post by: chenbeier on August 29, 2018, 04:11:14 PM

What was the reason now?