Balancing Chemical Equations Practice #2 by Adventures in Science - Free Printable

Problem Description:

The task is to balance the chemical equation provided in the image. The equation given is:

$$
\text{Mg} + \text{H}_2\text{O} \rightarrow \text{Mg(OH)}_2
$$

We need to ensure that the number of atoms of each element is the same on both sides of the equation.

---

Step-by-Step Solution:

#### 1. Identify the elements and their counts on both sides:
- Reactants (Left Side):
- Mg: 1 atom
- H: 2 atoms (from $\text{H}_2$)
- O: 1 atom (from $\text{H}_2\text{O}$)

- Products (Right Side):
- Mg: 1 atom
- H: 2 atoms (from $\text{Mg(OH)}_2$)
- O: 2 atoms (from $\text{Mg(OH)}_2$)

#### 2. Compare the counts:
- Mg: Balanced (1 atom on both sides).
- H: Balanced (2 atoms on both sides).
- O: Not balanced. There is 1 oxygen atom on the left side but 2 oxygen atoms on the right side.

#### 3. Balance the oxygen atoms:
- To balance the oxygen atoms, we need to increase the number of $\text{H}_2\text{O}$ molecules on the left side. Since there are 2 oxygen atoms on the right side and only 1 on the left side, we multiply $\text{H}_2\text{O}$ by 2.
- Updated equation:
$$
\text{Mg} + 2\text{H}_2\text{O} \rightarrow \text{Mg(OH)}_2
$$

#### 4. Recheck the counts:
- Reactants (Left Side):
- Mg: 1 atom
- H: 4 atoms (from $2 \times \text{H}_2$)
- O: 2 atoms (from $2 \times \text{H}_2\text{O}$)

- Products (Right Side):
- Mg: 1 atom
- H: 2 atoms (from $\text{Mg(OH)}_2$)
- O: 2 atoms (from $\text{Mg(OH)}_2$)

#### 5. Balance the hydrogen atoms:
- Currently, there are 4 hydrogen atoms on the left side and 2 hydrogen atoms on the right side. To balance the hydrogen atoms, we need to adjust the product side. However, the formula $\text{Mg(OH)}_2$ is fixed because it represents magnesium hydroxide, which has 2 hydrogens per molecule. Therefore, we need to adjust the coefficient of $\text{Mg(OH)}_2$ to 2.
- Updated equation:
$$
\text{Mg} + 2\text{H}_2\text{O} \rightarrow 2\text{Mg(OH)}_2
$$

#### 6. Final check:
- Reactants (Left Side):
- Mg: 1 atom
- H: 4 atoms (from $2 \times \text{H}_2$)
- O: 2 atoms (from $2 \times \text{H}_2\text{O}$)

- Products (Right Side):
- Mg: 2 atoms (from $2 \times \text{Mg(OH)}_2$)
- H: 4 atoms (from $2 \times \text{Mg(OH)}_2$)
- O: 4 atoms (from $2 \times \text{Mg(OH)}_2$)

- The equation is now balanced with respect to all elements.

---

Final Answer:

The balanced chemical equation is:

$$
\boxed{\text{Mg} + 2\text{H}_2\text{O} \rightarrow 2\text{Mg(OH)}_2}
$$