Question

What is the molar mass of the carbonate ion \( CO_3^{2-} \)?

• A. 15
• B. 20
• C. 25
• D. 60

Hint:

To find the molar mass of a polyatomic ion, simply add the atomic masses of the constituent elements, considering their respective counts in the ion.

Answer 1

The Correct Option is D

The carbonate ion \( CO_3^{2-} \) consists of one carbon (C) atom and three oxygen (O) atoms. The atomic mass of carbon is 12 g/mol, and the atomic mass of oxygen is 16 g/mol. Therefore, the molar mass of the carbonate ion is: \[ \text{Molar mass of } CO_3^{2-} = 12 + (3 \times 16) = 12 + 48 = 60 \text{ g/mol} \] Thus, the molar mass of the carbonate ion is 30 g/mol.