Which of the following is a feature of a thermochemical equation?

• A. It does not require the equation to be balanced.
• B. It only shows the reactants, not the products.
• C. It omits the physical states of reactants and products.
• D. It includes the enthalpy change (ΔH) for the reaction.

Answer: (D)

Verified step by step guidance

1. Understand that a thermochemical equation is a balanced chemical equation that includes the heat absorbed or released during the reaction, represented by the enthalpy change (\$\Delta H\$).
2. Recognize that balancing the chemical equation is essential because the enthalpy change depends on the stoichiometry of the reaction.
3. Note that thermochemical equations always show both reactants and products, as the reaction must be complete to relate the enthalpy change to the process.
4. Remember that physical states of reactants and products (such as (s), (l), (g), or (aq)) are included because enthalpy changes depend on these states.
5. Conclude that the defining feature of a thermochemical equation is the inclusion of the enthalpy change (\$\Delta H\$), which quantifies the heat change associated with the reaction.