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Sodium Acetate and HCl reaction forming a buffer?
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So I know in theory that when adding a strong acid to a weak base, a buffer will be created but I can't seem to wrap my head around it.
A buffer has to have both a conjugate base and the acid to become a buffer. In this case, sodium acetate is the base and the HCl displaces the Na+ to form NaCl (I think? or is it a different displacement reaction?) and CH3COOH which is the acetic acid.
But since those compounds are on either side of the equation (to say), how does the buffer work?? Does it count because they are reversible, or is it that not all of the base is broken apart so there's still some remaining therefore both the conjugate base and acid are present on one side?
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
A buffer has to have both a conjugate base and the acid to become a buffer. In this case, sodium acetate is the base and the HCl displaces the Na+ to form NaCl (I think? or is it a different displacement reaction?) and CH3COOH which is the acetic acid.
But since those compounds are on either side of the equation (to say), how does the buffer work?? Does it count because they are reversible, or is it that not all of the base is broken apart so there's still some remaining therefore both the conjugate base and acid are present on one side?
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
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(Original post by SleepyBeans)
So I know in theory that when adding a strong acid to a weak base, a buffer will be created but I can't seem to wrap my head around it.
A buffer has to have both a conjugate base and the acid to become a buffer. In this case, sodium acetate is the base and the HCl displaces the Na+ to form NaCl (I think? or is it a different displacement reaction?) and CH3COOH which is the acetic acid.
But since those compounds are on either side of the equation (to say), how does the buffer work?? Does it count because they are reversible, or is it that not all of the base is broken apart so there's still some remaining therefore both the conjugate base and acid are present on one side?
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
So I know in theory that when adding a strong acid to a weak base, a buffer will be created but I can't seem to wrap my head around it.
A buffer has to have both a conjugate base and the acid to become a buffer. In this case, sodium acetate is the base and the HCl displaces the Na+ to form NaCl (I think? or is it a different displacement reaction?) and CH3COOH which is the acetic acid.
But since those compounds are on either side of the equation (to say), how does the buffer work?? Does it count because they are reversible, or is it that not all of the base is broken apart so there's still some remaining therefore both the conjugate base and acid are present on one side?
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
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(Original post by SleepyBeans)
So I know in theory that when adding a strong acid to a weak base, a buffer will be created but I can't seem to wrap my head around it.
A buffer has to have both a conjugate base and the acid to become a buffer. In this case, sodium acetate is the base and the HCl displaces the Na+ to form NaCl (I think? or is it a different displacement reaction?) and CH3COOH which is the acetic acid.
But since those compounds are on either side of the equation (to say), how does the buffer work?? Does it count because they are reversible, or is it that not all of the base is broken apart so there's still some remaining therefore both the conjugate base and acid are present on one side?
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
So I know in theory that when adding a strong acid to a weak base, a buffer will be created but I can't seem to wrap my head around it.
A buffer has to have both a conjugate base and the acid to become a buffer. In this case, sodium acetate is the base and the HCl displaces the Na+ to form NaCl (I think? or is it a different displacement reaction?) and CH3COOH which is the acetic acid.
But since those compounds are on either side of the equation (to say), how does the buffer work?? Does it count because they are reversible, or is it that not all of the base is broken apart so there's still some remaining therefore both the conjugate base and acid are present on one side?
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
You have correctly identified that a buffer needs either a conjugate base and an acid-- or -- a conjugate acid and a base.
When you add a strong acid (ex. HCl) to a weak base (ex. NH4OH), the folowing reaction happens:
HCl + NH4OH ----> NH4Cl+ H2O
Now remember, a buffer in this case will be due to NH4Cl (the conjugate acid) and NH4OH (the weak base). However, the salt NH4Cl does not exist as NH4Cl but rather NH4+ and Cl-.
So this equilibrium gets set up
NH4OH + H+ -----> NH4+ + H20
The NH4OH is the weak base you have taken initially. The NH4+ formed is from the NH4Cl formation as I have outlined above.
The way this works is adding H+ ions shifts equilibrium to right, and removing H+ ions (or adding OH- ions) shifts equilibrium to left.
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#4
(Original post by SleepyBeans)
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
And how do the pH values change as you add increased amounts of HCl,, what does this mean???
Imagine in your conical flask you have the weak base. Then you add little drops of the acid (HCl). So adding a strong acid to a weak base initially leads to a larger drop in pH.
However, as you add more HCl drops, what is happening is a buffer is being set up (as I have explained above). A buffer's purpose is to mantain constant pH levels provided that you add small amounts of acid/base.
So initially, adding HCl leads to a larger drop in pH. But then when you add more HCl, a buffer sets up and then you have a lesser change in pH (if you have read about exponential graphs, it is somewhat the opposite of that).
Finally, if it is in your syllabus (certainly was in my A Levels), it can be worth to look at a graph of how pH changes (sometimes called titration curves). Chemguide is an absolute treasure, so I'll link them now: https://www.chemguide.co.uk/physical.../phcurves.html
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