Which of the following equations is correctly balanced for the reaction of hydrogen and oxygen to form water?

• A. 2 H_2 + 2 O_2 ightarrow 2 H_2O
• B. 2 H_2 + O_2 ightarrow 2 H_2O
• C. H_2 + O_2 ightarrow H_2O
• D. H_2 + rac{1}{2} O_2 ightarrow H_2O

Answer: (B)

Verified step by step guidance

1. Identify the reactants and products in the chemical equation: hydrogen gas (H_2) and oxygen gas (O_2) react to form water (H_2O).
2. Write the unbalanced chemical equation: \(\mathrm{H_2 + O_2 \rightarrow H_2O}\).
3. Count the number of atoms of each element on both sides of the equation. For example, on the reactant side, there are 2 hydrogen atoms per H_2 molecule and 2 oxygen atoms per O_2 molecule; on the product side, each H_2O molecule contains 2 hydrogen atoms and 1 oxygen atom.
4. Balance the equation by adjusting coefficients to ensure the number of atoms of each element is the same on both sides. Start by balancing hydrogen atoms, then oxygen atoms. For instance, placing a coefficient of 2 before H_2O gives 4 hydrogen atoms on the product side, so adjust the hydrogen reactant accordingly.
5. Verify the final balanced equation by recounting atoms of each element on both sides to confirm they are equal, ensuring the law of conservation of mass is satisfied.