Question

Balance the equation: S + HNO₃→ H₂SO₄ + NO₂ + H₂O

Answer 1

Balanced equation: S + 6HNO₃→ H₂SO₄ + 6NO₂ + 2H₂O 

Step 1: Write the unbalanced equation

S + HNO₃→ H₂SO₄ + NO₂ + H₂O

Step 2: Compare the number of atoms of reactants with the number of atoms of products.

	Reactants (left side)	Products (right side)
Element	Number of atoms	Number of atoms
S	1	1
H	1	4
O	3	7
N	1	1

Step 3: Now, first let us consider nitrogen atom. If we multiply 6 in the reactant (HNO₃) and product (in NO₂), we will get the equal number of atoms.

No. of atoms of nitrogen	Reactant (in HNO3)	Product (in NO2)
Initially	1	1
To balance	1 x 6 = 6	1 x 6 = 6

Step 4: Write the resulting equation:

S + 6HNO₃→ H₂SO₄ + 6NO₂ + H₂O

Step 5: Now check whether the equation is balanced or not by comparing the atoms

	Reactants (left side)	Products (right side)
Element	Number of atoms	Number of atoms
S	1	1
H	6	4
O	18	17
N	6	6

We find that the equation is not balanced yet. As the number of hydrogen and oxygen atoms are unequal on the two sides. 

First balance the oxygen atom.

Step 6: If we multiply 2 in the product (in H₂O) and 6, we will get the equal number of oxygen atoms on both sides.

No. of atoms of nitrogen	Reactant (in HNO3)	Product (in H2SO4 + + 6NO2 + H2O)
Initially	18	17
To balance	18	4 + 12 + 2 x 1 = 18

Step 7: Write the resulting equation:

S + 6HNO₃→ H₂SO₄ + 6NO₂ + 2H₂O

Step 8: Now check whether the equation is balanced or not by comparing the atoms.

	Reactants (left side)	Products (right side)
Element	Number of atoms	Number of atoms
S	1	1
H	6	6
O	18	18
N	6	6

Step 9: Write the resulting equation:

S + 6HNO₃→ H₂SO₄ + 6NO₂ + 2H₂O

We find that the equation is balanced now.

Step 10: Write down the final balanced equation:

S + 6HNO₃→ H₂SO₄ + 6NO₂ + 2H₂O