Questions: The gram-formula mass of (NH4)2CO3 is (A) 96.0 g / mol (B) 78.0 g / mol (C) 64 g / mol (D) 46 g / mol

Solution Steps

The chemical formula for ammonium carbonate is \((\mathrm{NH}_4)_2\mathrm{CO}_3\). This compound consists of:

• 2 ammonium ions \((\mathrm{NH}_4)^+\)
• 1 carbonate ion \((\mathrm{CO}_3)^{2-}\)

1. Ammonium Ion \((\mathrm{NH}_4)^+\):

   • Nitrogen (N): 1 atom × 14.01 g/mol = 14.01 g/mol
   • Hydrogen (H): 4 atoms × 1.008 g/mol = 4.032 g/mol
   • Total for one \((\mathrm{NH}_4)^+\): 14.01 + 4.032 = 18.042 g/mol

2. Carbonate Ion \((\mathrm{CO}_3)^{2-}\):

   • Carbon (C): 1 atom × 12.01 g/mol = 12.01 g/mol
   • Oxygen (O): 3 atoms × 16.00 g/mol = 48.00 g/mol
   • Total for \((\mathrm{CO}_3)^{2-}\): 12.01 + 48.00 = 60.01 g/mol

• Total mass of 2 ammonium ions: \(2 \times 18.042 = 36.084\) g/mol
• Total mass of 1 carbonate ion: \(60.01\) g/mol
• Total gram-formula mass of \((\mathrm{NH}_4)_2\mathrm{CO}_3\): \[ 36.084 + 60.01 = 96.094 \, \text{g/mol} \]

Final Answer