Which of the following is the correctly balanced chemical equation for the reaction: 2CH4(g) → C2H6(g) + H2(g)?

• A. CH4(g) → C2H6(g) + 2H2(g)
• B. 2CH4(g) → C2H6(g) + H2(g)
• C. CH4(g) → C2H6(g) + H2(g)
• D. 2CH4(g) → C2H6(g) + 2H2(g)

Answer: (D)

Verified step by step guidance

1. Identify the reactants and products in the given chemical equation: reactants are methane (CH4) and products are ethane (C2H6) and hydrogen gas (H2).
2. Count the number of atoms of each element on both sides of the equation to check if they are balanced. For example, count carbon (C) and hydrogen (H) atoms separately.
3. For the reactants side, multiply the number of molecules by the number of atoms per molecule. For instance, if you have 2 CH4 molecules, total carbon atoms = 2 × 1 = 2, and total hydrogen atoms = 2 × 4 = 8.
4. For the products side, do the same: count atoms in C2H6 and H2 molecules. For example, in C2H6, carbon atoms = 2, hydrogen atoms = 6; in H2, hydrogen atoms = 2 × number of H2 molecules.
5. Adjust the coefficients (the numbers in front of molecules) to ensure the total number of each type of atom is the same on both sides. The balanced equation will have equal numbers of carbon and hydrogen atoms on reactants and products sides.