titration curves (1 Viewer)

[geniass]

hey can anyone tell me how to find the end point( or is it the equivalence point) from a titration curve?????

 

[Xayma]

The end point or equivalence point (they are the same thing) is the vertical point of inflexion.

 

[jims]

Originally posted by geniass
hey can anyone tell me how to find the end point( or is it the equivalence point) from a titration curve?????

some better will answer, but one of them is when ur indicator changes colour while the other is when your solution is neutralised. if youve used the correct indicator then your equivalence point will b the same as your end point.

extra:

Originally posted by CM_Tutor
Equivalence Point: The point in a titration where the reactants are present in their stoichiometric ratio. That is, just enough titrant has been added from the burette to completely react all of the material in the conical flask, and thus neither is present in excess.

End Point: The point in a titration when the first permanent colour change of the indicator occurs.

 

[geniass]

Ok fair enough but on most titration curves there are huge points of inflexions that range upto 4 points of pH change. how do i know which one is the end point....?

 

[CM_Tutor]

Originally posted by geniass
hey can anyone tell me how to find the end point( or is it the equivalence point) from a titration curve?????

Titration curve gives the equivalence point - can't find the end point from it, as end point depends on indicator changing colour.

For the mathematically minded, the equivalence point is the volume corresponding to the vertical (or near vertical) inflexion. For the less mathematical, its the volume corresponding to the middle of the vertical bit.

Originally posted by Xayma
The end point or equivalence point (they are the same thing) ...

No, they aren't. Jims has quoted from a post of mine with the definitions. I encourage all to go and read the whole post - it addresses not only the equivalence point / end point distinction, but all the use of terms like "neutralisation" in acid / base titrations.

I realise that the distinctions may seem trivial, and that some texts seem to say equivalence point and end point are the same. Believe me when I say your examiners want you to understand the difference, and your lecturers (if you do Uni chem) will insist that you appreciate the distinction. The 1st years at my Uni spend a lot of lab time on various types of titration, and also have assessment on it, and you need to know the difference. It's better to learn it now than to have to unlearn and relearn later.

 

[Xayma]

Ok I understand now, my teachers just called them the same thing. *Remembers the difference.