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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: CIE alevel on July 18, 2009, 11:45:28 AM

Title: Back titration question
Post by: CIE alevel on July 18, 2009, 11:45:28 AM

Hi i'm new here....i'm doing the CIE A level chemistry syllabus. I hope some1 here has heard about it!

Here is a question on back titration. I don't really understand what is so "back" about it.

Please explain this doubt and help me the question below, i.e how it should be understood and the systematic method to the solution.
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi29.tinypic.com%2F2q2pstc.jpg&hash=ab0ad8217b5de8b1680159fa93cc57518e6dbcee)


Eagerly waiting for a reply  ;D..
 

Title: Re: Back titration question
Post by: Borek on July 18, 2009, 05:28:38 PM

http://www.titrations.info/back-titration

Title: Re: Back titration question
Post by: CIE alevel on July 19, 2009, 01:09:32 AM

Ok well the link u have provided didn't help much... :-\

Please could someone else give their input??  ???

Title: Re: Back titration question
Post by: Borek on July 19, 2009, 03:56:12 AM

Second paragraph of the linked text explains what back titration is - compare it with your situation.

Title: Re: Back titration question
Post by: marquis on July 19, 2009, 10:23:15 AM

This is an example only.  There are many varieties, but this should give you the basic idea.

Lets say you want to know how much acid is in a sample.  One way to do this is to directly titrate the acid.  Sometimes, there are interferences that stop that.

With a back titration, you add the sample to a known amount of base.  The acid in  the sample reacts with the base.  You then titrate the left over base in the sample with an acid  (this is where the  "back" titration comes from).  From this information, you can calculate the amount of acid in the initial sample.