alleryStart learning →Why is the carbonate ion described as a diprotic base?
AIt carries two oxygen atoms in its formula
BIt donates two protons in separate steps here
CIt can accept up to two protons in solution
DIt forms in two steps from carbonic acid here
Answer & Solution
Correct answer: C. It can accept up to two protons in solution
1. A base is classified by how many protons it can accept.
2. Carbonate takes one proton from water to become bicarbonate plus hydroxide.
3. Bicarbonate can take a second proton to become carbonic acid plus more hydroxide.
4. Two protons accepted in all makes carbonate a diprotic base.
5. This is why solutions of alkali metal carbonates are markedly alkaline.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.5 Polyprotic Acids_
Keep practising Acid-Base Equilibria
Browse all Acid-Base Equilibria questions for GCE A-Level (Singapore), or explore more Chemistry topics.
Related questions
Sort species into donor and acceptorTap the stronger acid each timeMatch each acid to its conjugate baseLine up three acids or three basesOver what pH range does methyl orange complete its colour change?What colour is phenolphthalein in a solution of pH below 8.3?Half the base needed for equivalence has been added to a weak acid. What is the pH of the What is the pH of 0.100 M acetic acid before any base is added, given Ka = 1.8 x 10^-5?