Confusing line in TBR about nonmetal hydroxides

[yellowjellybean]

Nonmetal oxides act as Lewis acids while their hydrated counterparts (nonmetal hydroxides, commonly known as oxyacids) act as Brønsted-Lowry acids. Both so3 and h2so4 react with hydroxide to form hso4-,so they are equivalent in terms of strength. The difference is that so3 is hydrated to become h2so4...

Can someone please explain to me what they are talking about in the bolded. I'm confused as to how it relates to the rest of the discussion. Thank you!

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[inasensegone]

Nonmetal oxides act as Lewis acids while their hydrated counterparts (nonmetal hydroxides, commonly known as oxyacids) act as Brønsted-Lowry acids. Both so3 and h2so4 react with hydroxide to form hso4-,so they are equivalent in terms of strength. The difference is that so3 is hydrated to become h2so4...

Can someone please explain to me what they are talking about in the bolded. I'm confused as to how it relates to the rest of the discussion. Thank you!

Perhaps you're confused because you didn't write out the equations?

SO3 + OH- ----> HSO4-
H2SO4 + OH- ----> HSO4- + H2O

So for every molecule of SO3 you remove one molecule of OH- (in effect you lower the pH). For every molecule of H2SO4 you also remove one molecule of OH- (in actuality it donates a proton which can combine with a hydroxide ion to form water as shown). In other words, both molecules remove one molecule of OH- each so they are equal in strength. SO3 is a nonmetal Oxide (Sulfur is a nonmetal) so it forms a lewis acid (an electron acceptor because it accepts the hydroxide). Sulfuric acid is the hydrated counterpart, the nonmetal hydroxide/oxyacid: AKA a bronsted-lowry acid (because it is a proton donor).

Notice how sulfuric acid's molecular formula (H2SO4) differs from sulfur trioxide (SO3) by a single water molecule (H2O). In other words, it is the hydrated counterpart.

If this is TBR GChem Chapter 4 Passage 12 you are referring to, it also shows the following reaction:

SO3 + H2O <--> H2SO4

I hope this makes sense... let me know if it doesn't.

 

[yellowjellybean]

Perhaps you're confused because you didn't write out the equations?

SO3 + OH- ----> HSO4-
H2SO4 + OH- ----> HSO4- + H2O

So for every molecule of SO3 you remove one molecule of OH- (in effect you lower the pH). For every molecule of H2SO4 you also remove one molecule of OH- (in actuality it donates a proton which can combine with a hydroxide ion to form water as shown). In other words, both molecules remove one molecule of OH- each so they are equal in strength. SO3 is a nonmetal Oxide (Sulfur is a nonmetal) so it forms a lewis acid (an electron acceptor because it accepts the hydroxide). Sulfuric acid is the hydrated counterpart, the nonmetal hydroxide/oxyacid: AKA a bronsted-lowry acid (because it is a proton donor).

Notice how sulfuric acid's molecular formula (H2SO4) differs from sulfur trioxide (SO3) by a single water molecule (H2O). In other words, it is the hydrated counterpart.

If this is TBR GChem Chapter 4 Passage 12 you are referring to, it also shows the following reaction:

SO3 + H2O <--> H2SO4

I hope this makes sense... let me know if it doesn't.

Thank you so much for the reply. The part that confuses me are how are they equal in strength? I thought that had to do with equilibrium constants.

 

[Blueprint MCAT Tutor]

I thought that had to D.O. with equilibrium constants.

lol

Who's the genius at SDN who decided to auto-correct every instance of the first person present-tense singular form of the verb "does" into to abbreviation D.O.

Suddenly that old classic song line looks pretty silly:

Do do that voodoo that you do so well!

 

[inasensegone]

Thank you so much for the reply. The part that confuses me are how are they equal in strength? I thought that had to do with equilibrium constants.

Ahhh I see what you are saying... Well I doubt we have to know this because SO3 isn't a super common compound that we have to deal with, but SO3 is supposedly super reactive with water to form H2SO4. SO3 is basically the dehydrated form of H2SO4 and as soon as you put it in water, it releases a ton of heat and creates H2SO4, which is pretty much infinitely soluble (miscible) in water.

From Wikipedia regarding Sulfur Trioxide (SO3):
SO3 is the anhydride of H2SO4. Thus, the following reaction occurs:

SO3 (g) + H2O (l) → H2SO4 (aq) (−88 kJ mol−1)
The reaction occurs both rapidly and exothermically, too violently to be used in large-scale manufacturing

So I guess the answer is, yes, even their equilibrium constants would be equivalent.

 

[yellowjellybean]

Ahhh me see what you are saying... Well me doubt we have to know this because SO3 isn't a super common compound that we have to deal with, but SO3 is supposedly super reactive with water to form H2SO4. SO3 is basically the dehydrated form of H2SO4 and as soon as you put it in water, it releases a ton of heat and creates H2SO4, which is pretty much infinitely soluble (miscible) in water.

From Wikipedia regarding Sulfur Trioxide (SO3):
SO3 is the anhydride of H2SO4. Thus, the following reaction occurs:

SO3 (g) + H2O (l) → H2SO4 (aq) (−88 kJ mol−1)
The reaction occurs both rapidly and exothermically, too violently to be used in large-scale manufacturing

So me guess the answer is, yes, even their equilibrium constants would be equivalent.

Hahaha I was cutting and pasting my reply, didn't mean to have such bad grammar. Anyway, thanks for putting the whole thing to rest for me!

 

[inasensegone]

Hahaha me was cutting and pasting my reply, didn't mean to have such bad grammar. Anyway, thanks for putting the whole thing to rest for me!

Lol! It really bothered me too at first! You're welcome 🙂

 

[Blueprint MCAT Tutor]

lol

Who's the genius at SDN who decided to auto-correct every instance of the first person present-tense singular form of the verb "does" into to abbreviation D.O.

Suddenly that old classic song line looks pretty silly:

Do do that voodoo that you do so well!

Okay so apparently I'm the idiot and it was an April Fools "joke". I'll leave my earlier post up to show what a crankypants mr. no-humor I really am.