Sulfuric acid is a polyprotic acid. Write balanced chemical equations for the sequence of reactions that sulfuric acid can undergo when it's dissolved in water.

H2SO4 + H2O> H3O + HSO4−

HSO4 + H2O> H3O + SO4−

Sulfuric acid is a very strong acid when it is dissolve in water or in aqueous solutions it ionizes completely forming hydronium ions (H3O+) and hydrogen sulfate ions (HSO4−).

If the it is placed in dilute solutions the hydrogen sulfate ions again dissociate forming more hydronium ions and sulfate ions (SO4−) so we can conclude that sulfuric acid reacts with water forming hydronium ions (H3O+) and hydrogen sulfate ions (HSO4−).

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H₂SO₄ (aq) + H₂O (l)  → HSO₄⁻ (aq) + H₃O⁺ (aq)

HSO₄⁻ (aq) + H₂O (l) ⇄  SO₄⁻²(aq) + H₃O⁺ (aq)           Ka

Explanation:

The sulfuric acid is a dyprotic acid.

It is a considered a strong acid but only the first deprotonation is strong.

Second deprotonation is totally weak

That's why we have equilibrium when it release the second proton.

Since a deprotonation is treated for a weak acid, the acid is considered not to completely dissociate, that's why the equilibrium