Which set of coefficients correctly balances the chemical equation: Mg + O_2 → MgO?

• A. Mg_2 + O_2 → 2 MgO
• B. 2 Mg + O_2 → 2 MgO
• C. Mg + O_2 → MgO_2
• D. Mg + 2 O_2 → MgO

Answer: (B)

Verified step by step guidance

1. Write down the unbalanced chemical equation: \(\mathrm{Mg} + \mathrm{O}_2 \rightarrow \mathrm{MgO}\).
2. Count the number of atoms of each element on both sides of the equation. On the left, there is 1 Mg atom and 2 O atoms; on the right, there is 1 Mg atom and 1 O atom.
3. Balance the oxygen atoms first. Since oxygen appears as \(\mathrm{O}_2\) on the left and as a single O in \(\mathrm{MgO}\) on the right, place a coefficient of 2 in front of \(\mathrm{MgO}\) to have 2 oxygen atoms on the right: \(\mathrm{Mg} + \mathrm{O}_2 \rightarrow 2 \mathrm{MgO}\).
4. Now balance the magnesium atoms. There are 2 Mg atoms on the right (due to the coefficient 2), so place a coefficient of 2 in front of Mg on the left: \$2 \mathrm{Mg} + \mathrm{O}_2 \rightarrow 2 \mathrm{MgO}$.
5. Verify that the equation is balanced by counting atoms again: 2 Mg atoms and 2 O atoms on both sides, confirming the balanced equation.