Oxides and Hydroxides
Metal oxides are usually bases.
metal oxide + water ? hydroxide base
Nonmetal oxides are usually acids.
nonmetal oxide + water ? oxoacid
Neutralization reactions:
H2SO4 + Ca(OH)2 ? CaSO4 + 2H2O
SO3 + Ca(OH)2 ? CaSO4 + H2O
H2SO4 + CaO ? CaSO4 + H2O
SO3 + CaO ? CaSO4