4.32C know that ethanol can be manufactured by: • reacting ethene with steam in the presence of a phosphoric acid catalyst at a temperature of about 300 ºC and a pressure of about 60–70 atm • the fermentation of glucose, in the absence of air, at an optimum temperature of about 30 ºC and using the enzymes in yeast 4.33C understand the reasons for fermentation, in the absence of air, and at an optimum temperature