2 equivalents to 1 is considered "roughly a 1:1 ratio??"

[johnwandering]

That is what the Berkley review says for buffer creation

There is supposed to be 1:1 mole ratio for a weak acid with its conjugate base
But answers to practice tests apparently allow a 2:1 equivalent as "roughly a 1:1"


Is this right??
and why??

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[loveoforganic]

pH = pKa + log(A-/HA)

log(1/1) = 0

log(2/1) = 0.3

This is a pretty negligible difference in pH.

 

[MLT2MT2DO]

That is what the Berkley review says for buffer creation

There is supposed to be 1:1 mole ratio for a weak acid with its conjugate base
But answers to practice tests apparently allow a 2:1 equivalent as "roughly a 1:1"


Is this right??
and why??

I believe the "hard fast rule" is anything within the 10:1 or 1:10 ratio is considered a buffer.

 

[johnwandering]

So, if a question asks "what is a way to make a buffer"


9 parts weak acid, 1 part weak conjugate base


Would be a correct answer???

 

[Plasticup]

edit: deleted

 

[johnwandering]

Thank you!!!


=)