Two competing industrial pathways for the synthesis of ethanol (C2H5OH\text{C}_2\text{H}_5\text{OH}C2H5OH) are outlined below:
Pathway 1 (Direct Catalytic Hydration):
C2H4(g)+H2O(g)⇌C2H5OH(g) \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{O(g)} \rightleftharpoons \text{C}_2\text{H}_5\text{OH(g)} C2H4(g)+H2O(g)⇌C2H5OH(g)Pathway 2 (Anaerobic Fermentation):
C6H12O6(aq)→2C2H5OH(aq)+2CO2(g) \text{C}_6\text{H}_{12}\text{O}_6\text{(aq)} \to 2\text{C}_2\text{H}_5\text{OH(aq)} + 2\text{CO}_2\text{(g)} C6H12O6(aq)→2C2H5OH(aq)+2CO2(g)Identify one starch- or sugar-rich crop grown in large quantities that can be harvested to supply the glucose (C6H12O6\text{C}_6\text{H}_{12}\text{O}_6C6H12O6) required for Pathway 2.
Identify the specific acid catalyst used in Pathway 1 and state the typical reaction temperature (including units) required for this industrial process.
Pathway 2 is carried out in the strict absence of air. State why the introduction of oxygen into the fermentation vessel must be avoided.
A biotechnology firm is planning to construct an ethanol production facility in a rural district that has extensive agricultural cooperatives growing corn (maize) but has no access to crude oil pipelines or petrochemical refinery infrastructure. Suggest three reasons why the firm should select Pathway 2 rather than Pathway 1 for this new facility.
In a laboratory, ethanol can be converted back into ethene. Write a balanced chemical equation for this reaction and identify the role of the concentrated acid (such as sulfuric or phosphoric acid) used to facilitate this transformation.