The balanced chemical equation for the reaction of nitrous acid (HNO2) with oxygen (O2) to form nitric acid (HNO3) is 3 HNO2 + O2 → 3 HNO3, with equal numbers of nitrogen and oxygen atoms on both sides.
To balance the chemical equation HNO2 + O2 → HNO3, we need to ensure that the number of atoms of each element is the same on both sides of the equation.
Starting with the nitrogen atoms, we can see that there is one nitrogen atom on both sides.
However, we need to ensure the oxygen atoms are balanced as well.
The reactants have two oxygen atoms in O2 and only one in HNO2, while the product HNO3 has three oxygen atoms.
When we balance the oxygen atoms, we notice that by having three HNO2 molecules reacting with one O2 molecule, we form three HNO3 molecules:
3 HNO2 + O2 → 3 HNO3
The numbers of N and O atoms on either side of the equation are now equal, so the equation is balanced.