Which of the following equations is balanced?
(a) The development reaction in silver-halide photography: 2 AgBr + 2 NaOH + C₆H₆O₂ → 2 Ag + H₂O + 2 NaBr + C₆H₄O₂
(b) The preparation of household bleach: 2 NaOH + Cl2 → NaOCl + NaCl + H₂O

Key Concepts

Balancing Chemical Equations

Balancing chemical equations involves ensuring that the number of atoms for each element is the same on both sides of the equation. This reflects the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. Each coefficient in the equation represents the number of molecules or moles of a substance, and adjusting these coefficients helps achieve balance.

Stoichiometry

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction. It allows chemists to predict the amounts of substances consumed and produced in a reaction based on balanced equations. Understanding stoichiometry is essential for calculating yields, determining limiting reactants, and performing conversions between moles, mass, and volume.

Types of Reactions

Chemical reactions can be classified into various types, such as synthesis, decomposition, single replacement, and double replacement. Each type has distinct characteristics and patterns that can help in predicting the products of a reaction. Recognizing the type of reaction can also aid in balancing equations, as certain reactions follow specific rules regarding the conservation of atoms and charge.