Question

From amongst the metals Sodium, Calcium, Aluminum, Copper, and Magnesium, name the metal

a. Which reacts with water only on boiling.

b. Another which does not even react with steam.

Answer 1

(a)

• Under different temperatures and conditions metals react with water in different ways. Some of the metal reacts with cold water, hot water, or steam, and some of the metals do not react with water.

Sodium$\left(\mathrm{Na}\right)$: The reaction condition of Sodium metal involves the use of cold water.

• Sodium is an alkali metal and it reacts with cold water to form its hydroxides.
• Sodium is extremely reactive in nature and is soft metal.
• The chemical reaction occurs as follows:
  $2\mathrm{Na}\left(\mathrm{s}\right)+\underset{\left(\mathrm{Cold}\mathrm{water}\right)}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Sodium}\mathrm{hydroxide})}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Calcium$\left(\mathrm{Ca}\right)$: The reaction condition of Calcium metal involves the use of cold water.

• Calcium is an alkali earth metal and it vigorously reacts with cold water to produce Calcium hydroxide and Hydrogen gas.
• The chemical reaction occurs as follows:
  $\mathrm{Ca}\left(\mathrm{s}\right)+\underset{\left(\mathrm{Cold}\mathrm{water}\right)}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Calcium}\mathrm{hydroxide})}{\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)}+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Aluminum$\left(\mathrm{Al}\right)$: The reaction condition of Aluminium metal involves the use of Boiling water.

• Decomposition reaction occurs when Aluminium reacts with boiling water to produce Aluminium hydroxide and Hydrogen gas.
• The reaction with boiling water proceeds slowly while reacting with Aluminium.
• The chemical reaction occurs as follows:
  $2\mathrm{Al}\left(\mathrm{s}\right)+\underset{\left(\mathrm{Boiling}\mathrm{water}\right)}{6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Aluminium}\mathrm{hydroxide})}{2\mathrm{Al}{\left(\mathrm{OH}\right)}_3\left(\mathrm{aq}\right)}+3{\mathrm{H}}_2\left(\mathrm{g}\right)$

Copper$\left(\mathrm{Cu}\right)$: Copper is a less reactive metal and does not give any reaction.

• When Copper is reacted with steam strongly it does not give any reaction, so it is placed at the end of the reactivity order of metals with water.
• Magnesium$\left(\mathrm{Mg}\right)$: The reaction condition of Magnesium metal involves the use of Boiling water.
• Magnesium reacts with boiling water, not with cold water.
• It reacts with water to form Magnesium oxide and Hydrogen gas.
• The chemical reaction occurs as follows:
  $\mathrm{Mg}\left(\mathrm{s}\right)+\underset{\left(\mathrm{Boiling}\mathrm{water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Magnesium}\mathrm{oxide})}{\mathrm{MgO}\left(\mathrm{s}\right)}+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Therefore, Magnesium and Aluminium reacts with water only on boiling.

(b)

Some of the metals are highly reactive while some are less. The metal which is less reactive toward water is Copper.

Copper does not react even with steam or at red heat.

The chemical reaction does not take place in the case of Copper.

$\mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \mathrm{No}\mathrm{reaction}$