CuO+H2=Cu+H2O\mathrm{CuO}+\mathrm{H}_{2}=\mathrm{Cu}+\mathrm{H}_{2} \mathrm{O}CuO+H2=Cu+H2O
H2 S+Cl2=S+2HCl\mathrm{H}_{2} \mathrm{~S}+\mathrm{Cl}_{2}=\mathrm{S}+2 \mathrm{HCl}H2 S+Cl2=S+2HCl
Cl2+H2=2HCl\mathrm{Cl}_{2}+\mathrm{H}_{2}=2 \mathrm{HCl}Cl2+H2=2HCl
HgCl2+Hg=Hg2Cl2\mathrm{HgCl}_{2}+\mathrm{Hg}=\mathrm{Hg}_{2} \mathrm{Cl}_{2}HgCl2+Hg=Hg2Cl2
