Are all hydroxides basic? What makes a base basic, and an acid acidic?

1 Answer
anor277
Feb 4, 2018

Both #H_2SO_4# and #HNO_3# contain hydroxides....i.e. #""^(-)O-stackrel+N=O(OH)#, and #(HO)_2S(=O)_2#

Explanation:

Both #H_2SO_4# and #HNO_3# contain hydroxides....and yet these are STRONG acids....

And an acid is typically the hydroxide of a non-metal, whereas a base is typically the hydroxide of a metal.

Non-metals, from the right hand side of the Periodic Table as we face it, TEND to polarize the electron density towards themselves, thereby weakening the #O-H# bond of their HYDROXIDES. On the other hand, metals, tend to have their electron density REMOVED by the oxygen centre....

Here we got #B(OH)_3#...and the oxygen TENDS to polarize the electron density of the #O-H# bond TOWARDS itself...

#(stackrel(delta+)H-stackrel(delta-)O-)_3B#

....and this the #H-O# is WEAKENED somewhat....#pK_a=9.24#

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