Question

What type of base would CaCO3

be in the following example:

CaCO3+H2SO4⟶CaSO4+CO2+H2O?

My understanding is that calcium carbonate cannot be a Brønsted–Lowry base because it does not gain a proton. Can someone please help me out?

Answer 1

Calcium carbonate acts as a Brønsted-Lowry base in the reaction with H2SO4 by accepting protons. The reaction does not involve hydroxide ions, demonstrating that Brønsted-Lowry bases need not contain them to neutralize acids. Calcium oxide and P2O5 are examples of base and acid anhydrides, respectively, forming Ca(OH)2 and H3PO4 when reacting with water.

Step-by-step explanation:

In the reaction CaCO3 + H2SO4 → CaSO4 + CO2 + H2O, calcium carbonate acts as a Brønsted-Lowry base even though it does not contain hydroxide ions. This is because Brønsted-Lowry bases are proton acceptors, and what happens in this reaction is that the carbonate ion (CO32-) from CaCO3 accepts protons from H2SO4, thus acting as a base. Meanwhile, H2SO4 is the Brønsted-Lowry acid since it donates protons.

When considering other examples like NH3 and CaO, they don't contain hydroxide ions but can still act as bases in the acid-base reaction. In this context, CaO serves as a strong base anhydride, which means it can form a base (Ca(OH)2) when reacted with water. Similarly, in a reaction where P2O5 is the acid anhydride, it forms the acid H3PO4 when reacting with water.