In the following three instances, which choice is greener in a chemical process? Explain. (a) A reaction that can be run at \(350 \mathrm{~K}\) for $12 \mathrm{~h}\( without a catalyst or one that can be run at \)300 \mathrm{~K}$ for \(1 \mathrm{~h}\) with a reusable catalyst. (b) A reagent for the reaction that can be obtained from corn husks or one that is obtained from petroleum. (c) A process that produces no by-products or one in which the by-products are recycled for another process.

: The greener process in this case will be the one that requires less energy input and has less environmental impact. Comparing the two reactions: 1. Without a catalyst, the reaction takes place at 350 K for 12 h. 2. With a catalyst, the reaction can occur at 300 K in just 1 h. The usage of a reusable catalyst makes this process more sustainable because it reduces the overall energy consumption and time for the reaction. Thus, the reaction with a reusable catalyst at 300 K for 1 h is greener.

: In this case, we need to consider the sustainability of the reagents and their environmental impact from the source. Comparing the two sources: 1. Corn husks are renewable resources and are repurposing what would otherwise be considered an agricultural waste. 2. Petroleum is a non-renewable resource, and its extraction and use are associated with higher greenhouse gas emissions and environmental pollution. Therefore, the reagent derived from corn husks has a lower environmental impact and is a more sustainable choice.

: The greener process will be determined by how the production process affects the environment. Let's compare the two options: 1. A process which produces no by-products means that there is no waste generated or any materials that need to be disposed of or recycled. This can lessen the environmental impact. 2. A process with recyclable by-products can be sustainable if the recycling process's energy consumption and environmental impact are minimal and the recycled by-products are repurposed effectively. Comparing both options, while both are potentially "green," the first option which does not produce any by-products may have a lower environmental impact due to the absence of any waste production. However, this also depends on the environmental cost of each of the processes in their entirety. Without more information on the specific chemical processes, both options indicate an environmentally friendly approach, with the by-products free process being potentially greener.