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# Where is the buffer region in a titration curve?

1. Isit that nearly horizontal region before the equivalence point?
2. yeah the massive horizontal lines.

edited: mixed up my verticals and horizontals. sorry!
3. Yeah the horizontal bit where the pH doesn't change much: hence the solution is being buffered!
4. (Original post by LeChat)
Yeah the horizontal bit where the pH doesn't change much: hence the solution is being buffered!
so basically is this when not enough acid or alkali has been added to change the ph so it remains constant?
5. (Original post by Aeon Prince)
Isit that nearly horizontal region before the equivalence point?
Its the part of the graph where is very steep (vertical) line i.e steeper gradient. And i'm guessing this has to do with what indicators to use, right?
6. (Original post by Pedus)
Its the part of the graph where is very steep (vertical) line i.e steeper gradient. And i'm guessing this has to do with what indicators to use, right?
actually no, im pretty sure the vertical line is the equivalence point. I believe the buffer region is that point before vertical line and that massive change in ph. The buffer region i think is the horizonal line before the vertical line because even though acid or alkali is being added, there isnt much change in ph as its being buffered so the ph remains constant.. I think thats right maybe someone else could shed some light on this
7. (Original post by Aeon Prince)
so basically is this when not enough acid or alkali has been added to change the ph so it remains constant?
Don't you just put Le Chatelier's principle into this, and say that the position of the equlibrium changes to opose or minimize the change? Isn't that the role of a buffer solution, as its a mixture that minimise pH changes on addition of small amounts of acid or base?
8. The vertical line is the bit where the pH is changing really really fast... so not being buffered at all. The middle of the vertical is the equivalence point. The horizontal bit is the buffer region becuase the mixture is 'soaking up' all your H+ or OH- ions, so the pH isn't changing much.
9. (Original post by Aeon Prince)
actually no, im pretty sure the vertical line is the equivalence point. I believe the buffer region is that point before vertical line and that massive change in ph. The buffer region i think is the horizonal line before the vertical line because even though acid or alkali is being added, there isnt much change in ph as its being buffered so the ph remains constant.. I think thats right maybe someone else could shed some light on this
Oh, no.. I actually totally agree with you there. My bad And thanks!
10. (Original post by LeChat)
The vertical line is the bit where the pH is changing really really fast... so not being buffered at all. The middle of the vertical is the equivalence point. The horizontal bit is the buffer region becuase the mixture is 'soaking up' all your H+ or OH- ions, so the pH isn't changing much.
would the end point also be that vertical line?
11. (Original post by Aeon Prince)
would the end point also be that vertical line?
Yep: if someone can tell me how to insert pictures into a post, I can show you a drawing i just did on Paint (but I don't know how to!)
12. Really stupid questions, but has this got anything to do with "Clock Reactions"? I'm thinking this because the indicator changes colour when in alkaline solution, or am I just getting stuff in a heebajeeba?
13. (Original post by LeChat)
Yep: if someone can tell me how to insert pictures into a post, I can show you a drawing i just did on Paint (but I don't know how to!)
You upload the image, and then get the link for it, then you put it in [IMG]insert link here[/img ]

14. Aha! Got it
Edit: pH on the y axis, volume of alkali added on the x axis
(assuming you're adding alkali to acid)
Attached Images

15. (Original post by Pedus)
Really stupid questions, but has this got anything to do with "Clock Reactions"? I'm thinking this because the indicator changes colour when in alkaline solution, or am I just getting stuff in a heebajeeba?
Hmm I don't think so, because it's the indicator that's changing colour, which isn't really taking part in the reaction (except for a bit of electron transfer), not one of the reactants. I think because it changes as a result of adding more of the alkaline rather than it going on it's own?
Hm, this makes sense to me, possibly not to anyone else though I'm really not very good at explaining myself...
16. (Original post by LeChat)
Aha! Got it
Edit: pH on the y axis, volume of alkali added on the x axis
(assuming you're adding alkali to acid)
17. (Original post by LeChat)
Aha! Got it
Edit: pH on the y axis, volume of alkali added on the x axis
(assuming you're adding alkali to acid)
Hey dude you know the end point is the middle of the equivalence point, but how do you see which is the middle lawl
if it asks for the ph?
18. (Original post by Aeon Prince)
Hey dude you know the end point is the middle of the equivalence point, but how do you see which is the middle lawl
if it asks for the ph?
Draw a line roughly centrally over the vertical bit, with equal bits of curve on each side, then take the two pH values at the top and bottom of the vertical section and find the midway point.
SO, for example: your vertical line starts at pH 2 and finishes at pH 9, your midpoint would be halfway between 2 and 9 = 5.5, so then you can see what volume of alkali you would need to add to be exactly neutralising the acid.
I hope this makes sense...

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