The number of electrons required to balance the following equation are :
`NO_(3)^(-)+4H^(+)rarr2H_(2)O+NO`

Options

A. 2 on right side
B. 3 on left side
C. 3 on right
D. 5 on left side

Answer

To determine the number of electrons required to balance the given redox reaction:

**Step 1: Write down the unbalanced equation.**
The unbalanced equation is:
\[ \text{NO}_3^{-} + 4\text{H}^{+} \rightarrow 2\text{H}_2\text{O} + \text{NO} \]

**Step 2: Count the number of atoms of each element on both sides.**
- Left side:
- Nitrogen (N): 1 (from NO3^-)
- Oxygen (O): 3 (from NO3^-) + 0 (from H^+) = 3
- Hydrogen (H): 4 (from H^+)

- Right side:
- Nitrogen (N): 1 (from NO)
- Oxygen (O): 2 (from 2H2O) + 0 (from NO) = 2
- Hydrogen (H): 4 (from 2H2O)

**Step 3: Balance the elements.**
- Nitrogen is balanced (1 on each side).
- Hydrogen is balanced (4 on each side).
- Oxygen is not balanced (3 on the left, 2 on the right).

**Step 4: Balance the oxygen atoms.**
To balance the oxygen atoms, we need to add electrons to the left side. The left side has 3 oxygen atoms, and the right side has 2. We can add 1 electron to the left side to account for the difference.

**Step 5: Calculate the charges on both sides.**
- Left side charge:
- NO3^- has a charge of -1.
- 4H^+ contributes a charge of +4.
- Total charge on the left = -1 + 4 = +3.

- Right side charge:
- NO is neutral (0 charge).
- 2H2O is also neutral (0 charge).
- Total charge on the right = 0.

**Step 6: Balance the charges by adding electrons.**
To balance the charge, we need to make the left side charge equal to the right side charge. The left side has a charge of +3, and the right side has a charge of 0. To balance this, we need to add 3 electrons to the left side.

**Final balanced equation:**
\[ \text{NO}_3^{-} + 4\text{H}^{+} + 3\text{e}^{-} \rightarrow 2\text{H}_2\text{O} + \text{NO} \]

**Step 7: Conclusion.**
The number of electrons required to balance the equation is 3.

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