Question

balance the following reaction. what is the stoichiometric coefficient for fe₂o₃?
__ fes₂ + o₂ → fe₂o₃ + __ so₂
options: 1, 11, 2, 8

Explanation:

Step1: Identify atoms to balance

The reaction is \( \text{FeS}_2 + \text{O}_2
ightarrow \text{Fe}_2\text{O}_3 + \text{SO}_2 \). We need to balance Fe, S, and O atoms.

Step2: Balance Fe atoms

Let the coefficient of \( \text{FeS}_2 \) be \( x \) and \( \text{Fe}_2\text{O}_3 \) be \( y \). For Fe: \( x = 2y \). Let's start with \( x = 2 \), then \( y = 1 \) (but check S and O). Wait, better to use trial. Let's set \( \text{FeS}_2 \) as 2. Then Fe in \( \text{Fe}_2\text{O}_3 \) would be 2, so \( \text{Fe}_2\text{O}_3 \) coefficient is 1? No, wait, \( \text{FeS}_2 \) has 1 Fe, so to get 2 Fe in \( \text{Fe}_2\text{O}_3 \), \( \text{FeS}_2 \) coefficient is 2. So \( 2\text{FeS}_2 + \text{O}_2
ightarrow 1\text{Fe}_2\text{O}_3 + \text{SO}_2 \). Now S: 22 = 4 S, so \( \text{SO}_2 \) coefficient is 4. Now O: on right, \( \text{Fe}_2\text{O}_3 \) has 3 O, \( \text{SO}_2 \) has 42 = 8 O, total O right: 3 + 8 = 11. On left, \( \text{O}_2 \) has 2 O per molecule. So coefficient of \( \text{O}_2 \) is \( \frac{11}{2} \), but we need integers. Multiply all coefficients by 2: \( 4\text{FeS}_2 + 11\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3 + 8\text{SO}_2 \). Now check: Fe: 41 = 4, 22 = 4. S: 42 = 8, 81 = 8. O: 112 = 22; 23 + 8*2 = 6 + 16 = 22. Balanced! So coefficient of \( \text{Fe}_2\text{O}_3 \) is 2? Wait no, wait the multiplied equation: \( 4\text{FeS}_2 + 11\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3 + 8\text{SO}_2 \). Wait, original trial: when we set \( \text{FeS}_2 = 2 \), \( \text{Fe}_2\text{O}_3 = 1 \), S = 4, \( \text{SO}_2 = 4 \), O on right: 3 + 8 = 11, so \( \text{O}_2 = 11/2 \). Multiply by 2: \( 4\text{FeS}_2 + 11\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3 + 8\text{SO}_2 \). Wait, but the options have 2 as an option. Wait, maybe I made a mistake. Wait the question's options: 1, 11, 2, 8. Wait the balanced equation is \( 4\text{FeS}_2 + 11\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3 + 8\text{SO}_2 \). So coefficient of \( \text{Fe}_2\text{O}_3 \) is 2.

Answer:

2 (the option with 2, i.e., the option labeled "2")