Question

An unbalanced chemical equation is shown:

2NaN3 → 2Na + N2

Which of the following statements explains why the equation is not balanced?

Four molecules of N2 should be produced during the decomposition.
Three molecules of N2 should be produced during the decomposition.
Four molecules of N2 should be produced during the synthesis reaction.
Three molecules of N2 should be produced during the synthesis reaction.

Answer 1

The unbalanced chemical equation given is:

\[ 2 \text{NaN}_3 \rightarrow 2 \text{Na} + \text{N}_2 \]

To check if the equation is balanced, we need to count the atoms of each element on both sides of the equation.

**On the left side (reactants):**
- Sodium (Na): 2 (from 2NaN3)
- Nitrogen (N): 6 (from 2NaN3, since each NaN3 contains 3 nitrogen atoms)

**On the right side (products):**
- Sodium (Na): 2 (from 2Na)
- Nitrogen (N): 2 (from N2, which contains 2 nitrogen atoms)

Now we see:
- For sodium: 2 Na on both sides (balanced).
- For nitrogen: 6 N on the left but only 2 N on the right (not balanced).

The missing nitrogen atoms suggest that there should be more nitrogen produced.

The correct way to reason about it is that during the decomposition of sodium azide (NaN3), each molecule of NaN3 decomposes to form 2 nitrogen atoms, therefore:

- If 2 NaN3 decomposes, it produces \( 2 \times 3 = 6 \) nitrogen atoms.

To balance the nitrogen on both sides of the equation, we would actually need 3 molecules of N2, since each N2 molecule contains 2 nitrogen atoms. This means \( 3 \times 2 = 6 \) nitrogen atoms would be produced.

Thus, the most relevant statement is:

**Three molecules of N2 should be produced during the decomposition.**