NH3 + O2 → NO + H2O. Which of the following is the balanced form of the above unbalanced equation?

• A. NH3 + O2 → NO + H2O
• B. 4 NH3 + 5 O2 → 4 NO + 6 H2O
• C. 2 NH3 + 2 O2 → 2 NO + 2 H2O
• D. 2 NH3 + 3 O2 → 2 NO + 3 H2O

Answer: (B)

Verified step by step guidance

1. Write down the unbalanced chemical equation: \(\mathrm{NH_3 + O_2 \rightarrow NO + H_2O}\).
2. Balance the nitrogen (N) atoms first. Since there is 1 N atom in NH₃ and 1 N atom in NO, balance by placing a coefficient of 4 in front of NH₃ and NO to have 4 N atoms on both sides: \$4\ \mathrm{NH_3 + O_2 \rightarrow 4\ NO + H_2O}$.
3. Next, balance the hydrogen (H) atoms. There are 4 NH₃ molecules, each with 3 H atoms, totaling 12 H atoms on the left. To balance hydrogen on the right, place a coefficient of 6 in front of H₂O (since each H₂O has 2 H atoms, \$6 \times 2 = 12\( H atoms): \)4\ \mathrm{NH_3 + O_2 \rightarrow 4\ NO + 6\ H_2O}$.
4. Finally, balance the oxygen (O) atoms. On the right side, there are 4 NO molecules (4 O atoms) and 6 H₂O molecules (6 O atoms), totaling 10 O atoms. To get 10 O atoms from O₂ molecules on the left, place a coefficient of 5 in front of O₂ (since each O₂ has 2 O atoms, \$5 \times 2 = 10\(): \)4\ \mathrm{NH_3 + 5\ O_2 \rightarrow 4\ NO + 6\ H_2O}$.
5. Verify that all atoms are balanced: N (4), H (12), and O (10) are equal on both sides, confirming the balanced equation.