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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Gameofketones on December 12, 2020, 02:49:31 AM

Title: Titration of oxalic acid with KMnO4
Post by: Gameofketones on December 12, 2020, 02:49:31 AM

In the 4th question should I approach it quantitatively like 0.1 N oxalic acid means 0.05M oxalic acid. But then I don't have the molarity of KMNO4 to predict the titre value.

Title: Re: Titration of oxalic acid with KMnO4
Post by: AWK on December 12, 2020, 03:31:08 AM

Quote from: Gameofketones on December 12, 2020, 02:49:31 AM

But then I don't have the molarity of KMNO4 to predict the titre value.

You are not asked about it.

Title: Re: Titration of oxalic acid with KMnO4
Post by: Gameofketones on December 12, 2020, 03:32:57 AM

Is it asking me if I would adjust in an experiment? Or should i predict if 5ml titre value is correct or not?

Title: Re: Titration of oxalic acid with KMnO4
Post by: AWK on December 12, 2020, 03:57:11 AM

How do you understand this sentence?

Title: Re: Titration of oxalic acid with KMnO4
Post by: Gameofketones on December 12, 2020, 03:59:17 AM

We have not yet done the experiment. This was given as an assignment..since we can't have physical classes. So I'm guessing we can only answer this after we do the experiment..

Title: Re: Titration of oxalic acid with KMnO4
Post by: AWK on December 12, 2020, 04:25:20 AM

All the questions for this exercise can be answered without knowing the specific concentration of permanganate. Moreover, for assignment 4 you can calculate the approximate values ​​of the permanganate concentration yourself if somehow it helps you better understand the problem.

Title: Re: Titration of oxalic acid with KMnO4
Post by: Borek on December 12, 2020, 04:27:21 AM

http://www.titrations.info/titrant-and-sample-volume

Title: Re: Titration of oxalic acid with KMnO4
Post by: Gameofketones on December 12, 2020, 05:22:58 AM

I got the titrant value 5ml doing in this manner..is this anywhere close to being correct?

Title: Re: Titration of oxalic acid with KMnO4
Post by: AWK on December 12, 2020, 05:33:09 AM

The greater the volume of the titrant, but not greater than the volume of the burette, the smaller the titration error.

Title: Re: Titration of oxalic acid with KMnO4
Post by: Gameofketones on December 12, 2020, 08:52:02 AM

I understand that titrant value must be greater for less errors. I'm confused because in the question they've said take either 10ml or 25ml. Should I calculate the concentration of KMnO4 and work them out separately?  Since 2 moles reacts with 5moles of oxalic acid, i got 0. 0125 moles of oxalic acid reacts with 0.005 moles of KMnO4. From the no. Of moles, I standardized it to 250ml and got 0.02M is this correct?

Title: Re: Titration of oxalic acid with KMnO4
Post by: AWK on December 12, 2020, 10:18:07 AM

Usually, a smaller volume is used for pre-titration. So I understand assignment 4 is for 25mL volume. This, therefore, corresponds to a permanganate concentration of 0.1 and 0.02 M respectively.

Title: Re: Titration of oxalic acid with KMnO4
Post by: Borek on December 12, 2020, 11:06:48 AM

Quote from: Gameofketones on December 12, 2020, 08:52:02 AM

I'm confused because in the question they've said take either 10ml or 25ml.

Most likely to allow you to choose the volume which produces smaller error.