The two main methods used to manufacture ethanol are shown below:
Reaction A (Hydration of ethene):
C2H4(g)+H2O(g)→C2H5OH(g) \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{O(g)} \to \text{C}_2\text{H}_5\text{OH(g)} C2H4(g)+H2O(g)→C2H5OH(g)Reaction B (Fermentation of glucose):
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)Name one crop that can be grown to provide the source of the glucose (C6H12O6\text{C}_6\text{H}_{12}\text{O}_6C6H12O6) used in Reaction B.
Identify the catalyst used in Reaction A and state the typical temperature used for this reaction.
Reaction B is carried out in the absence of air. State why the presence of air (oxygen) must be avoided during fermentation.
An energy company plans to construct a large-scale ethanol refinery in a region that has vast agricultural areas of sugarcane crops but has no oil refineries or crude oil resources. Suggest three reasons why the company should choose Reaction B rather than Reaction A for this plant.
Ethanol can be converted back into ethene in a laboratory. Write a balanced chemical equation for this reaction and state the role of the concentrated industrial acid catalyst used in this process.