Question

Name two metals which diaplace hydrogen from strong caustic alkalises.write the chemical equations in support of your answer

Answer 1

A common characteristic of most Alkali Metals is their ability to displace H2(g) from water. This is represented by their large, negative electrode potentials. In this event, the Group 1 metal is oxidized to its metal ion and water is reduced to form hydrogen gas and hydroxide ions. The general reaction of an alkali metal (M) with H2O (l) is given in the following equation:

2M(s)+2H2O(l)⟶2M+(aq)+2OH−(aq)+H2(g)2M(s)+2H2O(l)⟶2M(aq)++2OH(aq)−+H2(g)
From this reaction it is apparent that OH- is produced, creating a basic or alkaline environment. Group 1 elements are called alkali metals because of their ability to displace H2(g) from water and create a basic solution.

Alkali metals are also known to react violently and explosively with water. This is because enough heat is given off during the exothermic reaction to ignite the H2(g). One of the more reactive metals, cesium (Cs), is shown reacting with water in the figure below.