Formula of ammonium carbonate: (NH4)2CO3 Molar mass of ammonium carbonate = 96.11 g/mol Finding moles of ammonium carbonate: (6.975 g)/(96.11 g/mol) = 0.07257 moles Since there are 2 moles of ammonium ions in every mole of ammonium carbonate, there are 0.1451 moles of ammonium ions in the sample. (Note: rules for significant figures were followed in these calculations)