1/ Al + O2 → Al2O3 2/ K + O2 → K2O 3/ Al(OH)3 t0 → Al2O3 + H2O 4/ Al2O3 + HCl → AlCl3 + H20 5/ Al + HCl → AlCl3 + H2↑ 6/ Fe0 + HCl → FeCl2 + H20 7/ Fe203 + H2S04 → Fe2(S04)3 + H20 8/ Na0H + H2S04 → Na2S04 + H20 9/ Ca(0H)2 + FeCl3 → CaCl2 + Fe(0H)3 ↓ 10/ BaCl2 + H2S04 → BaS04↓ + HCl 11/ Fe(0H)3 t0→ Fe203 + H20 12/ Fe(0H)3 + HCl → FeCl3 + H20 13/ CaCl2 + AgN03 → Ca(N03)2 + AgCl ↓ 14/ P + 02 t0→ P205 15/ N205 + H20 → HN03 16/ Zn + HCl → ZnCl2 + H2↑ 17/ Al + CuCl2 → AlCl3 + Cu 18/ C02 + Ca(0H)2 → CaC03↓ + H20 19/ S02 + Ba(0H)2 → BaS03↓ + H20 20/ KMn04 t0 → K2Mn04 + Mn02 + 02↑