Question

Balance the following chemical equation:

___ PbO2 + ___ HCl → ___ PbCl2 + ___ H2O + ___ Cl2

a) 2 PbO₂ + 8 HCl → 2 PbCl₂ + 4 H₂O + 4 Cl₂
b) 1 PbO₂ + 4 HCl → 1 PbCl₂ + 2 H₂O + 2 Cl₂
c) 1 PbO₂ + 2 HCl → 1 PbCl₂ + 1 H₂O + 1 Cl₂
d) 2 PbO₂ + 4 HCl → 2 PbCl₂ + 2 H₂O + 2 Cl₂

Answer 1

To balance the chemical equation PbO2 + HCl → PbCl2 + H2O + Cl2, one must ensure that there are equal numbers of atoms for each element on both sides of the equation following the law of conservation of mass. The balanced equation is PbO2 + 4HCl → PbCl2 + 2H2O + Cl2.

Step-by-step explanation:

To balance the chemical equation given in the question — PbO2 + HCl → PbCl2 + H2O + Cl2 — we need to ensure that there are equal numbers of each type of atom on both sides of the equation. This principle is known as the conservation of mass.

First, let's count the number of atoms of each element in the reactants and products:

• Pb: 1 atom on both sides
• O: 2 atoms in PbO2; none in the other reactants
• H: Present only in HCl as reactants
• Cl: Present in HCl as reactants; in PbCl2 and Cl2 as products

To balance the equation, let's start by balancing the lead (Pb) and oxygen (O) atoms:

• Pb is already balanced with 1 atom on each side.
• Oxygen from PbO2 can be balanced with the H2O product by having 2 molecules of H2O formed.

Now let's balance chlorine (Cl) and hydrogen (H) atoms:

For every molecule of PbO2, we need 2 molecules of HCl to balance the O by producing 2 molecules of H2O. This introduces 2 Cl from HCl, which, when added to the Cl from PbCl2, makes 3 Cl on the right side. We need 2 more Cl to balance the 2 Cl atoms in the Cl2 molecule, so we need 4 total molecules of HCl on the left side to balance the equation.

Thus, the balanced equation is:

PbO2 + 4HCl → PbCl2 + 2H2O + Cl2

This corresponds to option b) 1 PbO2 + 4 HCl → 1 PbCl2 + 2 H2O + 2 Cl2.