Methanol (CH₃OH) is made industrially in two steps from CO and H₂. It is so cheap to make that it is being considered for use as a precursor to hydrocarbon fuels, such as methane (CH₄):
Step 1. CO(g) + 2 H₂(g) S CH₃OH(l) ΔS° = - 332 J/K
Step 2. CH₃OH₁l₂ → CH₄(g) + 1/2 O₂(g) ΔS° = 162 J/K
(m) If you were designing a production facility, would you plan on carrying out the reactions in separate steps or together? Explain.

Verified step by step guidance

1. <Step 1: Understand the reactions involved.> The problem involves two reactions: the formation of methanol from carbon monoxide and hydrogen, and the conversion of methanol to methane and oxygen. Each reaction has an associated change in entropy (ΔS°).
2. <Step 2: Analyze the entropy changes.> For Step 1, the reaction has a negative entropy change (ΔS° = -332 J/K), indicating a decrease in disorder. For Step 2, the reaction has a positive entropy change (ΔS° = 162 J/K), indicating an increase in disorder.
3. <Step 3: Consider the implications of entropy changes.> A negative ΔS° suggests that the reaction may be more favorable at lower temperatures, while a positive ΔS° suggests favorability at higher temperatures. This could affect the conditions under which each step is carried out.
4. <Step 4: Evaluate the practicality of combining the steps.> Combining the steps would require conditions that favor both reactions simultaneously, which may be challenging due to their differing entropy changes. Separate steps allow for optimization of conditions for each reaction.
5. <Step 5: Make a recommendation based on analysis.> Given the differing entropy changes and potential temperature requirements, it may be more practical to carry out the reactions in separate steps to optimize conditions for each reaction individually. This approach allows for better control over the production process.>

Key Concepts

Thermodynamics and Entropy

Thermodynamics is the study of energy transformations, and entropy (ΔS) is a measure of disorder in a system. In the context of chemical reactions, a negative ΔS indicates that the reaction leads to a decrease in disorder, while a positive ΔS suggests an increase. Understanding the entropy changes in the given reactions is crucial for predicting the feasibility and spontaneity of the processes involved in methanol and methane production.

Reaction Mechanism

A reaction mechanism outlines the step-by-step sequence of elementary reactions that lead to the overall chemical transformation. In this case, the production of methanol from CO and H2 occurs in two distinct steps. Analyzing whether to carry out these reactions separately or together requires understanding how the intermediate products behave and how they influence the overall efficiency and yield of the desired products.

Industrial Process Design

Industrial process design involves optimizing chemical reactions for large-scale production, considering factors like cost, efficiency, and safety. When deciding whether to conduct reactions in separate steps or in a continuous process, one must evaluate the energy requirements, potential for side reactions, and the economic implications of each approach. This decision impacts the overall productivity and sustainability of the methanol-to-methane conversion process.