Balance the following reaction by H & T method: Zn + HCl = ZnCl2 + H2

Explanation

To balance the reaction \( \text{Zn} + \text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \) using the H & T (Hit and Trial) method, follow these steps:

### Step 1: Write down the unbalanced equation
The initial unbalanced equation is:
\[ \text{Zn} + \text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

### Step 2: List the number of atoms of each element
Count the number of atoms for each element on both sides of the equation.

- **Left Side (Reactants):**
- Zn: 1
- H: 1
- Cl: 1

- **Right Side (Products):**
- Zn: 1
- H: 2
- Cl: 2

### Step 3: Identify which elements are unbalanced
From the counts:
- Zinc (Zn) is balanced (1 on both sides).
- Hydrogen (H) is unbalanced (1 on the left, 2 on the right).
- Chlorine (Cl) is unbalanced (1 on the left, 2 on the right).

### Step 4: Balance the hydrogen and chlorine
To balance the hydrogen, we can adjust the coefficient of HCl on the left side. Since there are 2 hydrogen atoms on the right side, we need to have 2 HCl on the left side.

So, we change the equation to:
\[ \text{Zn} + 2 \text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

### Step 5: Recount the atoms
Now, let's recount the atoms:

- **Left Side (Reactants):**
- Zn: 1
- H: 2 (from 2 HCl)
- Cl: 2 (from 2 HCl)

- **Right Side (Products):**
- Zn: 1
- H: 2
- Cl: 2

### Step 6: Confirm that all elements are balanced
Now, all elements are balanced:
- Zn: 1 on both sides
- H: 2 on both sides
- Cl: 2 on both sides

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

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