Period 3 Oxides

• Equation for the reaction between sodium and water:

  2Na(s) + 2H2O(l) -> 2NaOH(aq) +H2(g)
• Why shouldn't the reaction between sodium and water be done in a small reaction vessel?

  The temperature will increase significantly and reactants can shoot out of the tube.
• Equation for phosphorus(V) oxide with water:

  P4O10 + 6H2O -> 4H3PO4
• Explain, in terms of crystal structure and bonding, why silicon(IV) oxide has a higher melting point than phosphorus(V) oxide.


  SiO2 is macromolecular and the strong covalent bonds require a lot of energy to overcome. P4O10 is simple molecular so vdW forces can be broken much easier.
• Equation and observations when sodium is heated in oxygen:


  Eq: 4Na + O2 -> 2Na2O

  Yellow/orange flame and white solid observed
• A sample of the highest oxide of phosphorus was prepared in a laboratory. Describe a method for determining the melting point of the sample. State how the result obtained could be used to evaluate its purity

  • Sample in melting point apparatus
  • Heat gradually
  • Broad range of melting points = impurities