Question

Why must chemical equations be balanced?
Responses

Each compound in the equation must be arranged exactly the same.
Each compound in the equation must be arranged exactly the same.

Every atom must be counted and accounted for.
Every atom must be counted and accounted for.

The compounds in the reactants must match the compounds in the products.
The compounds in the reactants must match the compounds in the products.

Atoms disappear during chemical reactions.
Atoms disappear during chemical reactions.

Answer 1

Correct answer: Every atom must be counted and accounted for.

Why: Chemical reactions obey the law of conservation of mass — atoms are neither created nor destroyed, they are simply rearranged. Balancing an equation makes the number of each type of atom the same on both sides so stoichiometric (mole) relationships are correct. You balance by changing coefficients (not subscripts).

Why the others are wrong:
- "Each compound ... arranged exactly the same." — Not required; reactants can form different products.
- "The compounds in the reactants must match the compounds in the products." — False; compounds typically change during reactions.
- "Atoms disappear during chemical reactions." — False; atoms are conserved.