Other reactions

• Magnesium oxide is basic so it reacts with acids producing a salt and water.

  • $MgO+$$2HCl\rightarrow MgCl_2+$$H_2O$
  • $MgO+$$2HNO_3\rightarrow Mg\left(NO_3\right)+$$H_2O$

  The oxide ion accepts protons from the acid to form water:

  $O^{2-}+$$2H^+$$\rightarrow H_2O$
• Sodium oxide is basic so it also reacts with acids producing a salt and water.

  • $Na_2O+$$2HCl\rightarrow2NaCl+$$H_2O$
  • $Na_2O+$$H_2SO_4\rightarrow Na_2SO_4+$$H_2O$

  Sodium oxide dissolves in water and the oxide ion acts as a base and accepts $H^+$ions from the water or acid:

  • With water:$O^{2-}+$$H_2O\rightarrow2OH^-$
  • With acid: $O^{2-}+$$2H^+$$\rightarrow H_2O$
• Aluminium oxide is amphoteric as it reacts with both acids and bases: General equations

  • With acid: $Al_2O_3+$$6H^+$$\rightarrow2Al^{3+}+$$3H_2O$
  • With base: $Al_2O_3+$$2OH^-+$$3H_2O\rightarrow2Al\left(OH\right)_4^-$

  When aluminium oxide reacts with a base, the aluminate ion ($Al\left(OH\right)_4^-$) is formed: Overall equations

  • With HCl: $Al_2O_3+$$6HCl\rightarrow2AlCl_3+$$3H_2O$
  • With NaOH: $Al_2O_3+$$2NaOH+$$3H_2O+$$2NaAl\left(OH\right)_4$
• Silicon dioxide is an acidic oxide that will react with bases to form silicates. It will reacts with hot concentrated sodium hydroxide to form sodium silicate and water.

  $SiO_2+$$2NaOH\rightarrow Na_2SiO_3+$$H_2O$, $Na_2SiO_3$ is sodium silicate.

  Ionic equation: $SiO_2+$$2OH^-\rightarrow SO_3^{2-}+$$H_2O$
• Phosphoric(V) oxide is an acidic oxide so will react with bases forming phosphate salts.

  General equation: $12OH^-+$$P_4O_{10}\rightarrow4PO_4^{3-}+$$6H_2O$

  Overall equation: $12NaOH+$$P_4O_{10}\rightarrow4Na_3PO_4+$$6H_2O$

  (=To create the overall equation add the metal ion to both sides of the general equation.)
• Phosphoric(V) oxide reacts with basic oxides such as sodium oxide and magnesium oxide.

  • $6Na_2O+$$P_4O_{10}\rightarrow4Na_3PO_4$
  • $6MgO+$$P_4O_{10}\rightarrow2Mg_3\left(PO_4\right)_2$
• Phosphoric(V) acid reacts with basic oxides such as sodium oxide and magnesium oxide.

  • $3Na_2O+$$2H_3PO_4\rightarrow2Na_3PO_4+$$6H_2O$
  • $3MgO+$$2H_3PO_4\rightarrow Mg_3\left(PO_4\right)_2+$$3H_2O$
• Sulfur dioxide and sulfur trioxide are acidic oxides and so will react with bases.

  General equations:

  • $SO_2+$$2OH^-\rightarrow SO_3^{2-}+$$H_2O$
  • $SO_3+$$2OH^-\rightarrow SO_4^{2-}+$$H_2O$

  Overall equations: (Adding the metal ion to both sides of the general equation)

  • $SO_2+$$2NaOH\rightarrow Na_2SO_3+$$H_2O$
  • $SO_3+$$2KOH\rightarrow K_2SO_4+$$H_2O$