Q14.37 P - Chemistry: Molecular Nature Of Matter And Change

Question

Complete and balance the following equations:

(a) An active metal reacting with acid:

$\mathbf{Al}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{+}\mathbf{HCl}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{\to }$ 

(b) A saltlike (alkali metal) hydride reacting with water:

$\mathbf{LiH}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{+}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{\to }$ 

Step-by-Step Solution

Answer

The following balanced equations of the given reactions with the product are shown below:

a) $$\begin{gathered} 2Al\left(s\right)+6HCl\left(aq\right)\to 2AlC{l}_3\left(aq\right) + 3H_2\left(g\right) \\ Aluminum Hydrogen Aluminum Hydrogen \\ chloride chloride \end{gathered}$$

b) $$\begin{gathered} LiH\left(s\right)+H_{2}O\left(l\right)\to LiOH\left(aq\right)+H_2\left(g\right) \\ Lithium Water Lithium Hydrogen \\ hydride Hydroxide \end{gathered}$$

Step 1: Reaction of metal with acid (a)

Most metals react with acid to liberate hydrogen gas and form salts.

a) Like in reaction (a), Aluminum (Al) as a metal on reacting with hydrogen chloride (HCl) to form AlCl₃ as salt and liberates hydrogen gas, as shown in the reaction given below:

$$\begin{gathered} 2Al\left(s\right)+6HCl\left(aq\right)\to 2AlC{l}_3\left(aq\right) + 3H_2\left(g\right) \\ Aluminum Hydrogen Aluminum Hydrogen \\ chloride chloride \end{gathered}$$

Step 2: Reaction of metal hydride with water

Metal hydrides react with water to form metal hydroxide and liberate hydrogen gas.

b) In the given reaction (b), an ionic hydride such as lithium hydride (LiH) reacts with water to form lithium hydroxide (LiOH). It liberates hydrogen gas due to the formation of lithium hydroxide (LiOH), and our aqueous solution turns into a basic solution. The reaction of saltlike (alkali metal) hydride with water is shown below:

$$\begin{gathered} LiH\left(s\right)+H_{2}O\left(l\right)\to LiOH\left(aq\right)+H_2\left(g\right) \\ Lithium Water Lithium Hydrogen \\ hydride Hydroxide \end{gathered}$$