Question

Name the metal that combines slowly with cold water but at higher temperature the reaction is fast. Write balanced chemical equations to represent the two reactions.

Answer 1

1. Magnesium

It is an alkaline earth metal. It is represented by the atomic symbol $\mathrm{Mg}$.
Magnesium is a metal that combines slowly with cold water.

2. Reaction of Magnesium with water

The chemical equation that represents the reaction with cold water is given below.

$$\begin{gathered} \mathrm{Mg}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\stackrel{\mathrm{Heat}}{\to }\mathrm{Mg}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Magnesium}\mathrm{cold}\mathrm{water}\mathrm{Magnesium}\mathrm{oxide}\mathrm{Hydrogen} \end{gathered}$$

The heat in the reaction equation is used to represent the increase in the reactivity of Magnesium with water. Magnesium reacts faster with water at high temperatures.

The chemical equation that represents the reaction with steam is given below.

$$\begin{gathered} \mathrm{Mg}\left(\mathrm{s}\right)+\mathrm{hot}.{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)\to \mathrm{MgO}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Magneisum}\mathrm{water}\mathrm{Magnesium}\mathrm{oxide}\mathrm{Hydrogen}\mathrm{gas} \end{gathered}$$