Ethanol and water can be separated by using the technique of fractional distillation. This method exploits the difference in the boiling points of the two liquids. As ethanol has a lower boiling point than water, it vaporizes first when the solution is heated. The vapors of ethanol are then condensed and collected separately from the water.
To perform fractional distillation, the technician should heat the solution in a flask and allow the vapors to pass through a fractionating column, which has several condensing surfaces. As the vapors rise through the column, they condense and evaporate multiple times, causing the separation of the ethanol and water vapors. The ethanol vapors, now more concentrated, are then collected through a condenser, while the water is left behind.
Fractional distillation is the most suitable technique for separating ethanol and water as it is a simple and efficient method. It allows the separation of two liquids with close boiling points without the need for complex chemical reactions or high-energy inputs. Additionally, it is a common technique used in many industrial processes that require the separation of different liquids based on their boiling points.
Ethanol has a boiling point near 78°C and water has a boiling point of 100°C. A lab technician accidentally diluted a sample of ethanol with water.
Explain
how ethanol can be separated. Justify your choice of separating technique.
(5 marks)
3 answers
However, note that ethanol and water form an azeotrope at 95.63% ethanol/ 4.37% water which means that 100% separation can NOT be realized using this technique alone.
Thank you for pointing that out. It is true that an azeotrope is formed between ethanol and water at a certain ratio (in this case, at 95.63% ethanol/4.37% water). This can make it difficult to achieve complete separation of the two liquids using only fractional distillation. At this particular ratio, the boiling point of the mixture is lower than that of pure ethanol or water, making it impossible to separate them using fractional distillation.
To achieve higher purity of ethanol, additional steps such as azeotropic distillation or further purification using molecular sieves may be required. Alternatively, other separation techniques such as membrane separation, adsorption, or distillation using alternative solvents may be explored.
To achieve higher purity of ethanol, additional steps such as azeotropic distillation or further purification using molecular sieves may be required. Alternatively, other separation techniques such as membrane separation, adsorption, or distillation using alternative solvents may be explored.
2 answers