Steps on how to write an ionic equation
- Write down the normal balanced equation
NaOH + HCl → NaCl + H2O
- Write down the equation substituting the ionic compounds into their respective ions. covalent compounds which are partially ionised are written as the two ions formed while non-ionisable covalent molecules are written down as compounds.
Na+ OH– + H+ Cl– → Na+Cl– + H2O
- Omit the spectator ions. These are the ions that remain unchanged on both sides of the equation.
Na+OH– + H+ Cl– → Na+Cl– + H2O
- Write down the ionic equation. It must be noted that the charges on both sides should be equal. If no charge is present on the LHS then no charge should be present on the RHS
OH–(aq) + H+(aq) → H2O(l)
Acid base reaction
H2SO4 + CuO → CuSO4 + H2O
2H+SO42– + Cu2+ O2- → Cu2+SO42- + H2O
2H+(aq) + O2-(aq) → H2O(l)
3HNO3 + Al(OH)3 → Al(NO3)3 + 3H2O
3H+3NO3 + Al3+ 3OH– → Al3+3NO3– + 3H2O
H+(aq) + OH–(aq) → H2O(l)
Acid metal reaction
Zn + 2HCl → ZnCl2 + H2
Zn + H+Cl– → Zn2+Cl– + H2
Zn(s) + 2H+(aq)à→ Zn2+(aq) + H2(g)
Mg + H2SO4 → MgSO4 + H2
Mg + H+SO42- → Mg2+SO42- + H2
Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)
Acid Carbonate/Hydrogen Carbonate reaction
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
Ca2+ CO32- + H+Cl– → Ca2+Cl– + CO2 + H2O
2H+(aq)+ CO32-(aq)→ CO2(g) + H2O(l)
2NaHCO3 + H2SO4 → Na2SO4 + CO2 + H2O
Na+ HCO3– + 2H+SO42– → Na+SO42- + CO2 + H2O
2H+(aq) + HCO3– (aq)→ CO2(g) + H2O(l)
Metal Displacement
Mg + CuSO4 → MgSO4 + Cu
Mg + Cu2+ SO42- → Mg2+SO42- + Cu
Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)
Al + Zn(NO3)2 → Al(NO3)3 + Zn
Al + Zn2+NO3– → Al3+NO3– + Zn
2Al(s) + 3Zn2+(aq) → 2Al3+(aq) + 3Zn(s)
Non metal displacement
2KI + Cl2 → 2KCl + I2
K+ I– + Cl2 → K+ Cl– + I2
2I–(aq) + Cl2(g) → 2Cl–(aq) + I2(g)
NaBr + F2 → NaF + Br2
Na+ Br– + F2 → Na+ F– + Br2
2Br–(aq) + F2(g) → 2F–(aq) + Br2(g)
Ionic Precipitation
Pb(NO3)2 + NaI → PbI2 + NaNO3
Pb2+NO3– + Na+ I– → Pb2+I– + Na+NO3–
Pb2+(aq) + I–(aq) → PbI2(s)
CaCl2 + Na2CO3 → CaCO3 + 2NaCl
Ca2+Cl– + Na+ CO32- →Ca2+CO32- + Na+Cl–
Ca2+(aq) + CO32-(aq) → CaCO3(s)