CaCO3 có PTK =100g/mol
=> %Ca=\(\frac{40}{100}.100=40\%\)
%C=12:100.100=12%
%O=3.16:100.100=48%
H2SO4 có PTK =98
=> %H=2.1:98.100=2%
%S=32:98.100=32,7%
=> %O=100-2-32,7=65,3%
Fe2O3 có PTK =160
=> %Fe=56.2:160.100=70%
=> %O=100-70=30%
Mg(OH)2 có PTK: 58g/mol
=> %Mg=24:56.100=42,9%
%H=1.2:56.100=3,6%
=> %O=100-42,9-3,6=56,5%