Question

Consider the chemical equation below:

4Fe + 3O_{2} + x*H_{2}*O 4Fe(OH) 3

How many water molecules (shown as "x") are needed to balance the equation? (1 point)

12

3

6

2

Answer 1

To balance the given chemical equation:

4Fe + 3O₂ + xH₂O → 4Fe(OH)₃

First, let's break down the products. The compound 4Fe(OH)₃ consists of 4 iron (Fe) atoms and 12 hydroxide (OH) groups (since each Fe(OH)₃ contributes 3 OH groups and there are 4 Fe(OH)₃).

The hydroxide (OH) group is composed of one oxygen atom and one hydrogen atom. Therefore, we have:
- **Oxygen in OH**: 12 (from 4Fe(OH)₃)
- **Hydrogen from OH**: 12 (from 4Fe(OH)₃)

Now, let's account for the oxygen and hydrogen on the reactants side:
- We have 3 O₂ molecules, which provide 3 × 2 = 6 oxygen atoms.
- We need to account for the number of water (H₂O) molecules. Each molecule of H₂O contributes 1 oxygen atom and 2 hydrogen atoms.

Let’s write the equation for balancing oxygen and hydrogen. Since we have 12 hydroxide groups, we need:
- **12 oxygen atoms total** (6 from O₂ and the rest from H₂O).

Let’s set up the conservation of atoms for oxygen:
For the oxygen:
- From O₂: 6 atoms
- From H₂O: x atoms
Total oxygen needed = 12 atoms
So, we get:
6 + x = 12
x = 12 - 6
x = 6

Now for hydrogen, each H₂O contributes 2 hydrogen atoms:
Total hydrogen from H₂O = 2x
From the product side, we need 12 hydrogen (since there are 12 hydroxide groups).
So:
2x = 12
x = 6

Thus, 6 water molecules are required to balance the equation.

The answer is 6.