Reactions of Group 2 Elements with Water
• Mg + H2O ! MgO + H2 (with steam)
• Mg + 2H2O ! Mg(OH)2 + H2 (with warm water)
• Ca + 2H2O ! Ca(OH)2 + H2
• Sr + 2H2O ! Sr(OH)2 + H2
• Ba + 2H2O ! Ba(OH)2 + H2
Uses of Group 2 Elements
• TiCl4 (g) + 2Mg (l) ! Ti (s) + 2MgCl2 (l) (Extraction of titanium with magnesium)
• Mg(OH)2 + 2HCl ! MgCl2 + 2H2O (Magnesium hydroxide in medicine)
• Ca(OH)2 + CO2 ! CaCO3 + H2O (Limewater testing for CO2)
• CaO (s) + 2H2O (l) + SO2 (g) ! CaSO3 (s) + 2H2O (l) (Removing SO2 with CaO)
• CaCO3 (s) + 2H2O (l) + SO2 (g) ! CaSO3 (s) + 2H2O (l) + CO2 (g) (Removing SO2 with CaCO3)
Reactions of Group 7 Elements with Sulfuric Acid
• NaCl (s) + H2SO4 (l) ! NaHSO4 (s) + HCl (g) (white misty HCl fumes)
• NaBr(s) + H2SO4 (l) ! NaHSO4 (s) + HBr (g) (white misty HBr fumes)
• 2HBr (aq) + H2SO4 (l) ! Br2 (aq) + SO2 (g) + 2H2O (l) (choking, colourless SO2 / orange Br2 liquid)
• NaI(s) + H2SO4 (l) ! NaHSO4 (s) + HI (g) (white misty HI fumes)
• 2HI (aq) + H2SO4 (l) ! I2 (aq) + SO2 (g) + 2H2O (l) (choking, colourless SO2, purple I2 vapour)
• 6HI (g) + SO2 (g) ! H2S (g) 3I2 (g) 2H2O (l) (bad smells of H2S)
• 4HI (g) + SO2 (g) ! S (s) 3I2 (g) 2H2O (l) (yellow S solid
Reactions of Chlorine
• Cl2 (g) + H2O (l) ⇌ HClO (aq) + HCl (aq)
• (in sunlight) 2Cl2 (g) + 2H2O (l) ! 4HCl(aq) + O2 (g)
• Cl2 (g) + 2NaOH(aq) ! NaClO(aq) + NaCl(aq) + H2O (cold, dilute, aqueous NaOH)
Reactions of Period 3 Elements with Oxygen
• 4 Na + O2 ! 2 Na2O (yellow flame, white solid, vigorous)
• 2 Mg + O2 ! 2 MgO (white flame, white solid, vigorous)
• 4 Al + 3 O2 ! 2 Al2O3 (white flame, white solid, slow)
• Si + O2 ! SiO2 (white flame, white solid, slow)
• P4 + 5 O2 ! P4O10 (white flame, white solid, spontaneously combusts)
• S + O2 ! SO2 (pale blue flame, colourless gas, burns steadily)
• 2 S + 3 O2 ! 2 SO3 (pale blue flame, colourless gas, burns steadily)
Reactions of Period 3 Oxides with Water
• Na2O + H2O ! 2 NaOH (NaOH strong base)
• MgO + H2O ! Mg(OH)2 (Mg(OH)2 sparingly soluble)
• P4O10 + 6 H2O ! 4 H3PO4 (H3PO4 weak acid with many H+ ions)
• SO2 + H2O ! H2SO3 (H2SO3 weak acid)
• SO3 + H2O ! H2SO4 (H2SO4 strong acid)