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A balanced chemical equation is a representation of a chemical reaction, showing the relationship between the reactants and the products. In a balanced equation, the number of atoms of each element is the same on both sides of the equation, ensuring that the Law of Conservation of Mass is followed.

A balanced chemical equation provides the following information: 1. Reactants and Products: It shows the chemical species involved in the reaction, both as reactants (starting materials) and products (resulting materials). 2. Physical States: It indicates the physical states of reactants and products, such as solid (s), liquid (l), gas (g), and aqueous solution (aq). 3. Stoichiometry: It provides the stoichiometric coefficients, which represent the number of molecules or moles of each species involved in the reaction. These coefficients are used to understand the ratios in which different reactants combine and the ratios in which the products are formed. 4. Energy Change: If an energy change accompanies the reaction, it can be denoted as ΔH (enthalpy change) or ΔG (Gibbs free energy change) after the equation, indicating whether the reaction is exothermic (releases energy) or endothermic (absorbs energy). 5. Reaction Conditions: Some balanced chemical equations indicate reaction conditions, such as pressure, temperature, or the presence of catalysts that may be necessary for the reaction to occur.

The following balanced chemical equation for the combustion of methane ( CH_{4} ) provides various pieces of information: \( CH_{4(g)} + 2 O_{2(g)} \rightarrow CO_{2(g)} + 2 H_{2 O(l)} \; \Delta H = -890.3 kJ/mol \) In this equation, - Reactants: Methane ( CH_{4} ) and oxygen ( O_{2} ) - Products: Carbon dioxide ( CO_{2} ) and water ( H_{2 O} ) - Physical States: Gas (g) for methane, oxygen, and carbon dioxide; liquid (l) for water - Stoichiometry: One mole of methane reacts with two moles of oxygen to produce one mole of carbon dioxide and two moles of water - Energy Change: The reaction is exothermic with an enthalpy change of -890.3 kJ/mol