Which of the following statements about chemical reactions...

Which of the following statements about chemical reactions is false? a. When balancing a chemical equation, all subscripts must be conserved. b. When one coefficient is doubled, the rest of the coefficients in the balanced equation must also be doubled. c. The subscripts in a balanced equation tell us the number of atoms in a molecule. d. The phases in a chemical reaction tell us the nature of the reactants and products.

Which of the following statements about chemical reactions is false?
a. When balancing a chemical equation, all subscripts must be conserved.
b. When one coefficient is doubled, the rest of the coefficients in the balanced equation must also be doubled.
c. The subscripts in a balanced equation tell us the number of atoms in a molecule.
d. The phases in a chemical reaction tell us the nature of the reactants and products.

Key Concepts

Chemical Equation Balancing

Balancing chemical equations involves adjusting the coefficients—the multipliers placed in front of chemical formulas—to ensure that the number of atoms of each element is the same on both sides of the reaction. It is a fundamental technique in stoichiometry that does not involve changing the subscripts within the chemical formulas, which represent the fixed composition of the compounds.

Subscripts versus Coefficients

Subscripts in chemical formulas indicate the number of atoms of each element in a molecule and define its chemical identity. In contrast, coefficients represent the relative number of molecules or formula units involved in the reaction. While coefficients can be changed or scaled to balance the equation, the subscripts must remain constant because altering them would change the compound’s composition.

Scaling of Equations

Scaling a chemical equation involves multiplying all coefficients by the same factor to convert to an equivalent equation with larger numbers. The entire equation must be scaled uniformly; arbitrarily doubling one coefficient without adjusting the other coefficients would disturb the balance of atoms across the reaction, and thus, the stoichiometric relationships must be maintained on a whole-equation basis.

Phases of Matter in Chemical Reactions

The phase labels (such as solid, liquid, gas, and aqueous) indicate the physical states of the reactants and products in a chemical reaction. These labels provide important context about the reaction conditions and properties of the substances involved, though they do not influence the stoichiometric balancing of the chemical equation.

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