I came across this equation : $$\ce{ZnCO3 + H2SO4 → ZnSO4 + CO2 + H2O}$$ I wanted to know if $\ce{H2SO4}$ behaves like an acid in this reaction?

How do we generally determine if a compound acts as an acid?


1 Answer 1


In general, this depends on the definition of acid that you are using.

For this specific case, the Broensted definition would suffice. A Broensted acid is a reagent that donates a proton ($\ce{H^+}$) to its reaction partner.

The protons of the sulfuric acid are transfered (donated) to the carbonate anion, which gives carbonic acid. Carbonic acid decomposes into water and carbon dioxide, as you will experience when drinking sparkling water.

The key thing now is the affinity to donate said proton, which leads to the concept of acid strength and can be expressed in terms of $K_\mathrm{a}$ values.

If the anions were reversed and $\ce{ZnSO_4}$ would react with $\ce{H_2CO_3}$, one would find no reaction occuring.

This is a very easy explanation of the things going on, and I'd suggest you read a bit into

  • Acid definitions: Broensted and Lewis acids
  • Acid strength: Equilibrium of dissociation reactions
  • Conjugated Acid / Base pairs
  • $\begingroup$ Hey! Welcome to Chem SE you may want to start using the mhchem package for editing chemistry expressions over here. It saves a lot of time, I edited your post as an example. Get more details here. $\endgroup$ Jul 8, 2018 at 19:42

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