Chemical Forums

Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: dantheman00114 on April 15, 2009, 05:06:55 PM

Title: Titration Problem
Post by: dantheman00114 on April 15, 2009, 05:06:55 PM
In order to standardize a KMnO4 solution, 0.3301 g Na2C2O4 was dissolved in 30 mL water and 15 mL 3.0 M H2SO4. The KMnO4 solution was added to the Na2C2O4 solution until a pale pink color persisted. The titration took 31.1 mL of KMnO4 solution. What is the concentration of the KMnO4 solution?

I know that I'm probably going to have to start with a net ionic equation for the first addition of Na2C2O4 and H2SO4 with the sulfuric acid acting as the polyprotic acid.  Would I first have to convert to moles, and then figure out the concentration of the ions formed that will react with KMnO4 in the next reaction?? But then how do I write the equation and solve the equilibrium after the KMnO4 has been added?
Title: Re: Titration Problem
Post by: Borek on April 15, 2009, 05:36:59 PM
The only reaction you should worry about is KMnO4 + Na2C2O4.
Title: Re: Titration Problem
Post by: dantheman00114 on April 15, 2009, 06:50:00 PM
why does the H2SO4 not affect the problem? should i be dealing with the total volume of 45 mL then?
and in that regard, wouldn't the problem just simply be a M x V = M x V problem??
Title: Re: Titration Problem
Post by: Borek on April 16, 2009, 02:52:37 AM
Acid is there only to lower pH so that reaction between permanganate and oxalate proceeds fast.

This is a potentiometric (redox) titration (http://www.titrations.info/potentiometric-titration).