SO3 acidic

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Alex Tchekanov Dis 2k
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Joined: Sat Aug 24, 2019 12:16 am

SO3 acidic

Postby Alex Tchekanov Dis 2k » Mon Dec 02, 2019 8:00 pm

Why is SO3 considered acidic in water? What properties make this so? I know that it creates H2SO4 in water, but how does this make it a lewis acid?

kim 2I
Posts: 105
Joined: Thu Jul 25, 2019 12:17 am

Re: SO3 acidic

Postby kim 2I » Mon Dec 02, 2019 8:11 pm

SO3 is a non-metal oxide and non-metal oxides are known to be acidic in nature. It is a Lewis acid in that it accepts electrons, but I'm also a bit confused on how exactly this works.

Megan Cao 1I
Posts: 103
Joined: Sat Sep 07, 2019 12:18 am

Re: SO3 acidic

Postby Megan Cao 1I » Mon Dec 02, 2019 8:21 pm

SO42- in water is considered a lewis acid because it is derived from H2SO4. The dissociation of H2SO4 is:
H2SO4 + H2O <--> HSO4- + H3O
which then dissociates to:
HSO4- + H2O <--> SO42- + H3O

the product of SO42- in the second reaction shows that it's a conjugate base of HSO4- and H2SO4. In terms of lewis acids, the SO42- is acidic because it will give away its Hydrogens

Posts: 66
Joined: Thu Jul 25, 2019 12:15 am

Re: SO3 acidic

Postby 205296774 » Mon Dec 02, 2019 8:27 pm

H20 with its two lone-pairs is the electron donor so, therefore, the lewis acid. SO3 does not have any lone pairs, just 3 regions of electron density, so it gains electrons from the H20 and is, therefore, the lewis base.

Hope this helps!

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