Acid-Base Reactions: Is it Always a One-to-One Relationship?

[Knightycloud]

Lets say a certain chemical reacts with an acid. Does that make that chemical a base always and vice versa?

Like in S + NaOH → Na₂S + Na₂S₂O₃, Sulfur reacting with a base would it make S an acid?

Or do we call it a base or an acid, reacting with the opposite if it's producing water as a byproduct?

 

[Borek]

What classifies as an acid-base reaction depends on the definition of acid and base (and there are many, three most often used are Arrhenius definition, Bronsted-Lowry def. and Lewis def.).

Reaction you listed is too complex to be classified as a simple acid-base reaction, no matter which definition you use.

 

[Knightycloud]

So it is just a redox reaction, no acid base reaction? :)

 

[Borek]

You can put it this way. It is hardly a single step reaction, so it is quite possible some of the stages qualify as acid-base reactions.

 

[Knightycloud]

But Sulfur is not an acid in this reaction, right?

 

[Borek]

No, it is not.

 

[Knightycloud]

That's all I want to know. Thank you!