2Zn + O2 =2ZnO
2Ca + O2= 2 CaO
Mg + 2HCl =Mg C l2 + H2
2KNO3 =2KNO2 + O2
2Fe +3 Cl2 =2 FeCl3
Mg Cl2 + 2NaOH= Mg( OH ) 2 +2 NaCl
H2SO4 +2NaOH=Na2 SO4 +2H2O
MgCO3 = Mg O + CO2
Zn S +2 HCl = ZnCl2 +H2S
NH3 + HCl = NH4 Cl
2Al +3 S = A l 2 S3
2Ag NO3 + CaCl2 =2Ag Cl + Ca( NO3 )2