We need to balance an unbalanced skeletal chemical equation justify.

Answer

To balance the unbalanced skeletal chemical equation for the reaction between zinc and hydrochloric acid, we will follow these steps:

### Step-by-Step Solution:

1. **Write the Unbalanced Equation**:
The first step is to write the skeletal equation using the chemical formulas of the reactants and products. For the reaction between zinc (Zn) and hydrochloric acid (HCl), the products are zinc chloride (ZnCl₂) and hydrogen gas (H₂).
\[ \text{Zn} + \text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

2. **Count the Number of Atoms for Each Element**:
Next, we need to count the number of atoms of each element on both sides of the equation.
- **Left Side**:
- Zn: 1
- H: 1
- Cl: 1
- **Right Side**:
- Zn: 1
- H: 2
- Cl: 2

3. **Identify the Imbalance**:
From the counts, we can see that:
- Zinc (Zn) is balanced (1 on each side).
- Hydrogen (H) is unbalanced (1 on the left, 2 on the right).
- Chlorine (Cl) is unbalanced (1 on the left, 2 on the right).

4. **Balance the Equation**:
To balance the equation, we need to ensure that the number of atoms for each element is the same on both sides. We can balance the hydrogen and chlorine by placing a coefficient of 2 in front of HCl on the left side:
\[ \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

5. **Recount the Atoms**:
Now, we recount the atoms to ensure they are balanced:
- **Left Side**:
- Zn: 1
- H: 2 (from 2 HCl)
- Cl: 2 (from 2 HCl)
- **Right Side**:
- Zn: 1
- H: 2 (from H₂)
- Cl: 2 (from ZnCl₂)

6. **Final Balanced Equation**:
The balanced equation is:
\[ \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

7. **Justification for Balancing**:
We balance the equation to satisfy the law of conservation of mass, which states that mass can neither be created nor destroyed in a chemical reaction. This means that the total mass of the reactants must equal the total mass of the products.