Question

Complete the reaction below and balance it.

$\mathrm{PbO}+\mathrm{HCl}\to$

Answer 1

Answer:

The reaction between lead oxide($\mathrm{PbO}$) and hydrochloric acid($\mathrm{HCl}$) leads to the formation of lead chloride(${\mathrm{PbCl}}_2$) and water(${\mathrm{H}}_2\mathrm{O}$).

Chemical equation :

$\mathrm{PbO}\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{PbCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)$

General steps used for balancing a chemical equation:

Step 1

Let us first write the word equation for this reaction.

Lead oxide + Hydrochloric acid $\to$Lead chloride + Water

Step 2

Write the chemical equation for the reaction between lead oxide and hydrochloric acid.

$\mathrm{PbO}\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{PbCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)$

Step 3

Count the number of times an element is occurring on both LHS and RHS in this equation.

Components	Reactant	Product
Hydrogen	1	2
Oxygen	1	1
Chlorine	1	2
Lead	1	1

This is an unbalanced equation.

Step 4

• To balance a chemical equation, choose a reactant or a product that has the maximum number of atoms in it.
• In that compound, select an element which has the maximum number of atoms.

In this equation we shall select $\mathrm{HCl}$ i.e. hydrochloric acid and the element Chlorine in it.

To balance the Chlorine atoms, let us multiply hydrochloric acid ($\mathrm{HCl}$) molecule by 2 on the left-hand side. The equation can now be expressed as

Components	Reactants	Product
Hydrogen	1*2	2
Chlorine	1*2	2

Step 5

Now there are 2 Chlorine atom, 2 Hydrogen atom, 1 lead atom and 1 Oxygen atom on both the sides of the equation.Hence the equation is balanced.

The balanced chemical equation is given by:

$\mathrm{PbO}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{PbCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$