If 26.23 mL of potassium permanganate solution is required to titrate 1.041 g of ferrous ammonium sulfate hexahydrate, #FeSO_4(NH_4)_2SO_4 * 6H_2O#, chow do you calculate the molarity of the #KMnO_4# solution.?

1 Answer
Feb 21, 2017

Answer:

You can do it like this:

Explanation:

We have 1.041 g of ferrous ammonium sulfate hexahydrate.

The #sf(M_r=392.14)#

#:.##sf(n_(Fe^(2+))=m/M_(r)=1.041/392.14=0.002654color(white)(x)"mol")#

Set up the equation from the two 1/2 equations:

#sf(MnO_4^(-)+8H^++5erarrMn^(2+)+4H_2O" "color(red)((1)))#

#sf(Fe^(2+)rarrFe^(3+)+e" "color(red)((2)))#

To get the electrons to balance we need to X #sf(color(red)((2)))# by 5 then add to #sf(color(red)((1))rArr)#

#sf(MnO_4^(-)+8H^++cancel(5e)+5Fe^(2+)rarrMn^(2+)+4H_2O+5Fe^(3+)+cancel(5e))#

This tells that 5 moles of #sf(Fe^(2+))# react with 1 mole of #sf(MnO_4^-)#

#:.##sf(n_(MnO_4^(-))=0.002654/5=5.3093xx10^(-4))#

#sf(c=n/v)#

#:.##sf([MnO_4^(-)]=(5.3093xx10^(-4))/(26.23/1000)=0.02024color(white)(x)"mol/l")#