Question

State the visible changes and give equations for reactions, when :

A piece of Na is added to cold water⇡

Answer 1

Visible change :

• The change which is visible to an observer during a chemical reaction is called visible change. For example, change in colour, change in temperature, formation of precipitate, formation of bubbles ,etc.

Conclusion :

• When sodium is added to water , sodium melts to form a ball that moves around on the surface. It fizzes rapidly and the hydrogen may burn with an orange flame before the sodium disappears
• $$\begin{gathered} 2\mathrm{Na}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{NaOH}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Sodium}\mathrm{Water}\mathrm{Sodium}\mathrm{Hydrogen} \\ \mathrm{hydroxide}\mathrm{gas} \end{gathered}$$