KMnO4 & (NH4)2C2H4 Redox Titration

[v***@gmail.com]

I am performing a redox titratrion between KMnO4 (Potassium
Permanganate) and (NH4)2C2H4 (Ammonium Oxalate) that has been acidified
with sulfuric acid. The Ammonium Oxalate is .00400M, and per 1L about
10mL on sulfuric acid was added to the Ammonium Oxalate solution. When
performing the titration, I have observed a phenomenon I have never
seen before. I started by putting 5mL of Potassium Permanganate in a
beaker, and adding 1mL of Ammonium Oxalate. I then proceeded to swirl
the solution, and it took nearly 5 minutes for the pink color of the
Patassium Permanganate to dissapear. However, as I get closer to the
end point (about 15mL of KMnO4 added in this case), it takes
progressevley less time to swirl the color out of the solution. Does
anyone know why this would be?

[Farooq W]

Post by v***@gmail.com
I am performing a redox titratrion between KMnO4 (Potassium
Permanganate) and (NH4)2C2H4 (Ammonium Oxalate) that has been

acidified

Post by v***@gmail.com
with sulfuric acid. The Ammonium Oxalate is .00400M, and per 1L about
10mL on sulfuric acid was added to the Ammonium Oxalate solution. When
performing the titration, I have observed a phenomenon I have never
seen before. I started by putting 5mL of Potassium Permanganate in a
beaker, and adding 1mL of Ammonium Oxalate. I then proceeded to swirl
the solution, and it took nearly 5 minutes for the pink color of the
Patassium Permanganate to dissapear. However, as I get closer to the
end point (about 15mL of KMnO4 added in this case), it takes
progressevley less time to swirl the color out of the solution. Does
anyone know why this would be?

Excellent observation! Did you slightly heat the solution just before
the titration? The reaction of ammonium oxalate (NH4)2C2O4 (or any
oxalate for that matter) with KMnO4 is quite complex. Initially when
you add KMnO4, the pink color persists for few seconds as if the end
point has been reached immediately, then disappears. This is because
the Mn(II) ions generated by the reduction of permanganate act as a
catalyst, thus speeding up the oxidation of oxalate by KMnO4. There are
no Mn(II) ions in the flask as you begin the titration, the reaction
proceeds slowly but as the concentration of manganese ions increases
you observe immediate disappearance of purple color till a fiant pink
color persists showing that all oxalate has been consumed.

[Unknown]

,;I am performing a redox titratrion between KMnO4 (Potassium
,;Permanganate) and (NH4)2C2H4 (Ammonium Oxalate) that has been acidified
,;with sulfuric acid. The Ammonium Oxalate is .00400M, and per 1L about
,;10mL on sulfuric acid was added to the Ammonium Oxalate solution. When
,;performing the titration, I have observed a phenomenon I have never
,;seen before. I started by putting 5mL of Potassium Permanganate in a
,;beaker, and adding 1mL of Ammonium Oxalate. I then proceeded to swirl
,;the solution, and it took nearly 5 minutes for the pink color of the
,;Patassium Permanganate to dissapear. However, as I get closer to the
,;end point (about 15mL of KMnO4 added in this case), it takes
,;progressevley less time to swirl the color out of the solution. Does
,;anyone know why this would be?

Add some manganous sulfate before you start the titration. You should
be able to figure out what is happening. If not repost.