Will a solution of #H_2SO_4//SO_4^(2-)# be a buffer? Why or why not?

1 Answer
Truong-Son N.
Jan 26, 2018

No. In fact, the sulfuric acid would greatly protonate #"SO"_4^(2-)#, probably completely, and then you would just get one bisulfate species for the most part. That is not a buffer.

A buffer is best made between some weak electrolyte and its conjugate.

Thus,

  • If you were to use #"SO"_4^(2-)#, then it must be paired with #"HSO"_4^(-)#.
  • If you use #"NH"_3#, you must pair it with #"NH"_4^(+)#.
  • If you use #"CH"_3"COOH"#, you must pair it with #"CH"_3"COO"^(-)#.

#"H"_2"SO"_4# is a strong acid... so it cannot be paired with anything to make any decent buffer.

CHALLENGE: What should the maximum #([SO_4^(2-)])/([HSO_4^(-)])# ratio be in order to make the best buffer?

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