Reactions of Period 3, Na - Cl
 

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1. Reaction of the elements with oxygen.

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Sodium: Burns with a yellow flame.

4Na(s)  +  O2(g)   "  2Na2O(s)

Magnesium: Burns with a brilliant white flame.

2Mg (s)  +  O2 (g)   "  2MgO (s)

Aluminium: The aluminium needs to be finely divided.

4Al(s)  +  3O2(g)   "  2Al2O3 (s)

Silicon:                                             Si(s)  +  O2(g)   "  SiO2 (s)

Phosphorus: Burns vigorously with a brilliant pinkish-white flame. White P inflames spontaneously in air; red P needs heating.

4P(s)  +  5O2(g)   "  P4O10 (s)

Sulphur: Burns with a brilliant blue flame.

S(s)  +  O2(g)   "  SO2(g)

Chlorine does not react directly with oxygen.
 

Inorganic reactions contents

Reactions with oxygen
Reactions with chlorine
Reactions with water

2. Reaction of the elements with chlorine.

 

Dry chlorine is passed over the heated elements.

Sodium:                                              2Na(s)  +  Cl2(g)  "  2NaCl(s)

Magnesium:                                          Mg(s)  +  Cl2(g)  "   MgCl2(s)

Aluminium:                                        2Al(s)  +  3Cl2(g)  "   2AlCl3(s)

Silicon:                                                Si(s)  +  2Cl2(g)  "   SiCl4(l)

Phosphorus:                                       2P(s)  +  3Cl2(g)   "   2PCl3(l)

Dry chlorine is passed over heated phosphorus; heating PCl3 with excess chlorine gives PCl5, a pale yellow solid:                                                    PCl3(l)  +  Cl2(g)  "   PCl5(s)

Sulphur:                                                2S(l)  +  Cl2(g)  "   S2Cl2(l)

  

3. Reaction of the elements with water.

 

Sodium: The reaction is vigorous and the sodium melts and floats on the water.

2Na(s)  +  2H2O(l)  "   2NaOH(aq)  +  H2(g)

Magnesium: Magnesium reacts slowly with cold water to give magnesium hydroxide, but very exothermically with steam to give the oxide.

                                                  Mg(s)  +  H2O(g)  "   MgO(s)  +  H2(g)

Aluminium: Steam is passed over the finely-divided heated metal.

                                                 2Al(s)  +  3H2O(g)  "   Al2O3(s)  +  3H2(g)

Silicon, phosphorus and sulphur do not react with water.

Chlorine: The reaction is an equilibrium.

                                                 Cl2(aq)  +  H2O(l)HOCl (aq)  +  HCl(aq)

 

© JRG Beavon 2007