What is the #"acidium species"# in water?

1 Answer
Nov 11, 2015

Answer:

Because #H^+# is a conception, as is #H_3O^+#. The actual species (as far as anyone knows) is a cluster of water molecules #(OH_2)_n#, with an extra #H^+#, to give #(O_nH_(2n+1))^+#.

Explanation:

Water molecules are exceptionally proton dense (and also dense in terms of molecules); the charge can pass from molecule to molecule in the cluster rather than an actual proton; in a sense this is proton tunneling. The same type of charge transfer can occur with the hydroxide ion, #OH^-#. If you have ever played rugby, consider a maul, where the forwards pass the pill from hand to hand while moving forward (and here the ball is the extra #H^+#; of course rugby is a macroscopic phenomenon).

Other ions of course cannot tunnel by charge transfer, and must physically transfer across the solution.