When sucrose is fermented to produce ethanol why is it not possible to obtain a final solution containing more than 10-15% ethanol?
Does this have to do with azeotropes? However, I thought this was possible? I am confused, please help.
When sucrose (table sugar) is fermented to produce ethanol, the process is typically carried out by yeast through a process known as alcoholic fermentation. During this process, yeast converts the sugar into ethanol and carbon dioxide.
The reason it is not possible to obtain a final solution containing more than 10-15% ethanol is primarily due to the formation of an azeotrope. An azeotrope is a mixture of two or more substances that have a constant boiling point and composition. In the case of ethanol and water, a maximum boiling point (or azeotropic point) of approximately 78.2°C is reached when these two substances are mixed in a specific ratio.
The azeotrope formed by ethanol and water has a composition of about 95.6% ethanol and 4.4% water. This means that if you try to distill a solution with a higher ethanol concentration, the resulting vapor will have the same composition as the original solution. Consequently, the distillate cannot be further concentrated by traditional distillation methods.
However, it is important to note that it is possible to obtain solutions with higher ethanol concentrations through more advanced distillation techniques, such as molecular sieves or pressure-swing distillation. These methods are able to break the azeotropic behavior and increase the ethanol concentration. However, they involve more complex equipment and processes.
In summary, the reason it is not possible to obtain a final solution containing more than 10-15% ethanol when fermenting sucrose is due to the formation of an azeotrope between ethanol and water, which limits the maximum concentration that can be achieved through traditional distillation methods.