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 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.

We need to compare two scenarios: 1. A reaction that can be run at 350 K for 12 hours without a catalyst. 2. A reaction that can be run at 300 K for 1 hour with a reusable catalyst. When comparing these two scenarios, we can consider the total energy consumption and the environmental benefits of using a catalyst. Running a reaction at a lower temperature (300 K) is more energy-efficient than running it at a higher temperature (350 K). Additionally, a catalyst can speed up the reaction, reducing the reaction time from 12 hours to 1 hour. Since the catalyst is reusable, its use won't generate waste, making it a greener choice for the environment. Conclusion: The reaction run at 300 K for 1 hour with a reusable catalyst is greener.

We need to compare two sources for obtaining a reagent: 1. Corn husks 2. Petroleum Corn husks are a renewable and sustainable source because they are a by-product of corn production. Their extraction does not cause significant environmental damage, as they would otherwise be left unused. Moreover, using corn husks can promote a closed-loop cycle and minimize waste generation. In comparison, petroleum is a non-renewable and finite resource, extracted through environmentally harmful processes such as oil drilling and fracking. Conclusion: A reagent obtained from corn husks is greener than one obtained from petroleum.

We need to compare two scenarios: 1. A process that produces no by-products 2. A process in which the by-products are recycled for another process A process that doesn't produce any by-products can reduce environmental impact by eliminating waste generation, making it a greener option. However, a process that produces by-products that can be fully recycled for other processes can also provide environmental benefits, by minimizing waste generation and resource consumption. In this case, both options can be considered green chemical processes, depending on other factors involved, such as energy consumption and resource sustainability. If other factors are equal, both processes can be deemed green, with the recycling process providing added benefits of utilizing waste. Conclusion: Both options are green. A process with no by-products is simpler and may have less room for error, but a process that recycles by-products can be more resource-efficient.