Question

1. choose the best answer. when the following equation is balanced, what is the coefficient for o₂? fe + o₂ → __ fe₂o₃ options: 1, 2, 3, 4

Explanation:

Step1: Balance Fe atoms

On the right, $\ce{Fe2O3}$ has 2 Fe atoms. So put 2 in front of Fe? Wait, no, let's start with O. The product $\ce{Fe2O3}$ has 3 O atoms, but $\ce{O2}$ is diatomic. So find the least common multiple of 2 (from $\ce{O2}$) and 3 (from $\ce{Fe2O3}$ O atoms), which is 6. So for O: in $\ce{Fe2O3}$, to get 6 O, we need 2 $\ce{Fe2O3}$ (since 23=6 O). Then Fe: 2 $\ce{Fe2O3}$ has 4 Fe, so put 4 in front of Fe. Now O: 2 $\ce{Fe2O3}$ has 6 O, so $\ce{O2}$ needs to provide 6 O, so 3 $\ce{O2}$ (32=6). Let's check: 4 Fe + 3 $\ce{O2}$ → 2 $\ce{Fe2O3}$. Fe: 4 on left, 4 (22) on right. O: 6 (32) on left, 6 (2*3) on right. Balanced. So coefficient for $\ce{O2}$ is 3.

Step2: Verify the balanced equation

The balanced equation is $4\ce{Fe} + 3\ce{O2}
ightarrow 2\ce{Fe2O3}$. Checking each element: Fe: 4 on left, 4 (2×2) on right. O: 6 (3×2) on left, 6 (2×3) on right. All balanced. So the coefficient for $\ce{O2}$ is 3.

Answer:

3