[submar1ney]

Referring to common aqueous ions, i have to write empirical formulae for:

Nitric acid = H⁺NO₃^-

Calcium Carbonate = Ca²⁺CO_3^2-

Carbon dioxide = CO₂

Are these correct and am i on the right lines?

Cheers

[Arkcon]

No, you have given the ionic formulas, which come in handy but do not fit the definition of empirical formula.  Your assignment is funny 'tho, empirical formula are meant to show elemental ratios (i.e. the empirical formula of hydrogen peroxide, H₂O₂, is HO.  For the compounds you list, molecular formula and empirical formula are the same.

[Alpha-Omega]

I am not sure what your assignment is; however, you cannot go more empirical tahn what you have:

Nitric acid = H+NO3-:  HNO3 is the empirical formula for HNO3


Calcium Carbonate = Ca2+CO32-  :  CaCO3 is the empirical formula for CaCO3


Carbon dioxide = CO2 :  CO2 is the empirical formula for CO2

These formulae cannot be reduced further..

See this link:

http://www.chem.tamu.edu/class/majors/tutorialnotefiles/empirical.htm