Write an equation for the formation of each compound from its elements in their standard states, and find ΔH°_rxn for each in Appendix IIB. d. CH₃OH(l)

Verified step by step guidance

1. Identify the elements that make up CH_3OH(l): carbon (C), hydrogen (H), and oxygen (O).
2. Determine the standard states of these elements: C is graphite, H is H_2(g), and O is O_2(g).
3. Write the balanced chemical equation for the formation of CH_3OH(l) from its elements in their standard states: C(graphite) + 2H_2(g) + 1/2O_2(g) -> CH_3OH(l).
4. Look up the standard enthalpy of formation (ΔH_f°) for CH_3OH(l) in Appendix IIB.
5. Use the ΔH_f° value from the appendix to find ΔH °_rxn for the formation reaction.

Key Concepts

Standard State

The standard state of a substance is its most stable form at 1 bar of pressure and a specified temperature, usually 25°C. For elements, this means their natural state, such as O2(g) for oxygen and C(s) for carbon. Understanding standard states is crucial for writing formation equations, as it ensures that the reactants are in their correct physical states.

Formation Reaction

A formation reaction is a chemical reaction in which one mole of a compound is formed from its constituent elements in their standard states. The equation for such a reaction typically includes the elements on the reactant side and the compound on the product side. For example, the formation of methanol (CH3OH) from carbon, hydrogen, and oxygen would involve writing the balanced equation that reflects this process.

Enthalpy Change (ΔH°rxn)

The enthalpy change (ΔH°rxn) for a reaction at standard conditions represents the heat absorbed or released during the reaction. It is a key thermodynamic quantity that can be found in tables or calculated using Hess's law. For the formation of CH3OH(l), ΔH°rxn indicates whether the reaction is exothermic or endothermic, providing insight into the stability of the compound relative to its elements.