There are a few rules you must know before you start writing skeleton equations!
- A Covalent compound contains 2 or more nonmetals, uses prefixes like mono, di, etc, and does not need to switch the charges.
- An Ionic compund contains a metal and nonmetal or acid, the charges must be switched.
- Single elements are written by themselves unless they are part of the 7 diatomic molecules (H2, O2, F2, Br2, I2, N2, Cl2), then you must add a 2 subscript.
Let's start with dinitrogen tetraoxide → nitrogen + oxygen (covalent compound):
You would write it as N2O4 → N2 + O2, then you may balance it if you want. Balanced, it would be N2O4 → N2 + 2 O2.
Here is an ionic compound:
Potassium bromide + Aluminum Sulfate → Potassium Nitrate + Aluminum Bromide
KBr + Al(NO3)3 → KNO3 + AlBr3, and then we balance it: 9 KBr + 3 Al(NO3)3 → 9 KNO3 + 3 AlBr3
Here are a few others:
Fe3O2 + C2 → CO + Fe
Balanced:
2 Fe3O2 + 2 C2 → 2 CO + 6 Fe
Ca + AlCl3 → CaCl2 + Al
Balanced:
3 Ca + 2 AlCl3 → 3 CaCl2 + 2 Al
You would write it as N2O4 → N2 + O2, then you may balance it if you want. Balanced, it would be N2O4 → N2 + 2 O2.
Here is an ionic compound:
Potassium bromide + Aluminum Sulfate → Potassium Nitrate + Aluminum Bromide
KBr + Al(NO3)3 → KNO3 + AlBr3, and then we balance it: 9 KBr + 3 Al(NO3)3 → 9 KNO3 + 3 AlBr3
Here are a few others:
- Potassium Iodide + Lead (II) nitrate → Potassium Nitrate + Lead (II) Iodide
- Iron (III) Oxide + Carbon → Carbon Monoxide + Iron
Fe3O2 + C2 → CO + Fe
Balanced:
2 Fe3O2 + 2 C2 → 2 CO + 6 Fe
- Calcium + Aluminum Chloride → Calcium Chloride + Aluminum
Ca + AlCl3 → CaCl2 + Al
Balanced:
3 Ca + 2 AlCl3 → 3 CaCl2 + 2 Al