Secondary IV • 3yr.
Hi!
I'm not sure if I understand how a titration can help us to know the concentration of a solution ... Can someone explain it to me please?
Thank you very much in advance!
Explanation from Alloprof
This Explanation was submitted by a member of the Alloprof team.
Hi!
Thank you for your question 😊
In an acid-base titration, the goal is to obtain a solution whose pH is neutral thanks to acidic and basic reagents. The products will therefore be water and salt.
As the desired pH is neutral, we can then use an acid-base indicator which changes color when the pH is 7.
The aim of this experiment is to know the concentration of one of the solutions present in the reagents. We can use the principle of acid-base neutralization, measuring the number of moles of reactants when the pH is neutral, that is, when the acids and bases have combined.
Take the example of a reaction between NaOH and HCl. If we have a solution of unknown concentration of HCl and a solution of known concentration of NaOH, we can do a titration to find out the unknown variable.
By adding a colorimetric indicator to HCl, NaOH can be added into the solution by titration to the end point, where the pH will be neutral.
It will then be possible to determine the volume of NaOH necessary to neutralize this HCl solution. As the NaOH concentration is known, the number of moles can be calculated.
So the number of moles of HCl can be determined and then the concentration of HCl can be calculated, as the volume is known.
Hope that answers your question! Do not hesitate to rewrite us!