Question

State what you would observe when: Sodium is burnt in air.

Answer 1

• Sodium is one of the most reactive metals.
• When a piece of sodium reacts with oxygen; it burns vigorously with a brilliant golden yellow flame, and sodium oxide and sodium peroxide are formed.
• $$\begin{gathered} \underset{\mathrm{Sodium}}{4\mathrm{Na}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Sodium}\mathrm{oxide}}{2{\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right)} \\ \underset{\mathrm{Sodium}}{2\mathrm{Na}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Sodium}\mathrm{peroxide}}{{\mathrm{Na}}_2{\mathrm{O}}_2\left(\mathrm{s}\right)} \end{gathered}$$
• When sodium peroxide (${\mathrm{Na}}_2{\mathrm{O}}_2$) is dissolved in water, alkaline sodium hydroxide is formed which turns red litmus blue.
• $\underset{\mathrm{Sodium}\mathrm{oxide}}{{\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}$