The correct order of increasing acidic nature is?

  1. #"H"_3"O"^+ < "NH"_4^+ < "HF" < "OH"^(-) < "H"_2"O"#

  2. #"NH"_4^+ < "HF" < "H"_3"O"^+ < "H"_2"O" < "OH"^-#

  3. #"OH"^(-) < "H"_2"O" < "NH"_4^+ < "HF" < "H"_3"O"^+#

  4. #"H"_3"O"^+ < "HF" < "H"_2"O" < "NH"_4^+ < "OH"^-#

1 Answer
Oliver S.
Apr 8, 2018

3.

Explanation:

Acidic nature is determined by a low #pH#.
#pH# is given by:
#pH=-log [H_3O^+]#
where #[H_3O^+]# is the concentration of oxonium ions- so the most acidic species in this bunch must be the oxonium ion-#H_3O^+#

Conversely, an alkaline character is given by a high #pH#, which implies a high concentration of #OH^-# ions- so this must be what has the last acidic character of the listed ions and molecules.

Hence the only appropriate one seems to be option 3.

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