Simple Acid/Base Question regarding OH- and H+

[Zaids37]

I was just going through a question's answer which stated that since a compound accepted an OH group, it has accepted electrons and thus acts as a Lewis Acid.

By this principle is it ok to presume that if a compound DONATES an OH group then it has given up electrons and thus acts as a lewis base? Or are there other confounds that can come into play? In addition how would Adding/Removing an H+ effect if it is a lewis acid or base (Gains H+ means lewis base, looses H+ means lewis acid?...)

Sorry if these are simple/dumb questions but gen chem (especially these basic principles) have always seemed foreign to me.

Thanks!

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[kraskadva]

Basic definitions first:

Arrhenius Acid: Donates H+ to break a bond (must be in aq solution)
Bronsted-Lowry Acid: Donates H+ to break a bond (any solution)
Lewis Acid: Accepts lone pair of electrons to form a bond (any solution)

Arrhenius Base: Donates OH- to break a bond(must be in aq solution)
Bronsted-Lowry Base: Accepts H+ to form a bond (any solution)
Lewis Base: Donates lone pair of electrons to form a bond (any solution)

vvvin red

I was just going through a question's answer which stated that since a compound accepted an OH group, it has accepted electrons and thus acts as a Lewis Acid.

By this principle is it ok to presume that if a compound DONATES an OH group then it has given up electrons and thus acts as a lewis base? No, by definition that's an A base. Or are there other confounds that can come into play? In addition how would Adding/Removing an H+ effect if it is a lewis acid or base (Gains H+ means lewis base Can be Lewis base, but that is the definition of B-L base. , looses H+ means lewis acid? No, that's an A or B-L acid...)

Sorry if these are simple/dumb questions but gen chem (especially these basic principles) have always seemed foreign to me.

Thanks!

You just have to keep your definitions straight and only evaluate one at a time.
Arrhenius is all about breaking bonds in water (so H+ or OH- are kicked off).
Bronsted-Lowry is all about transfer of H+ between 2 molecules.
Lewis is all about transfer of electrons to form bonds.

Something can qualify as more than one of these, but there's no set rule about crossover, you just have to evaluate each compound.

 

[Zaids37]

Thanks so much! You're right my problem was trying to connect them all together in terms of hydrogen gaining/loss and electron gaining/loss. Thanks again for answering my past few questions!

 

[kraskadva]

You're welcome