To produce absolute alcohol (100%) from rectified spirit (95.6% alcohol), the remaining 4.4% water must be removed by a drying agent such as
Correct answer: A. Calcium oxide
- A. Calcium oxide
- B. Calcium chloride
- C. Calcium carbonate
- D. Carbon monoxide
Explanation
if we add lime (CaO) to the rectified spirit then the water of the mixture can be absorbed by the lime. As a result, the percentage of ethanol will be changed. So the mixture will not act as an azeotropic mixture. In this way, we can prepare absolute alcohol by using the distillation method from a rectified spirit.To remove the remaining water from rectified spirit (95.6% alcohol) and obtain absolute alcohol (100% alcohol), a drying agent is used. The drying agent commonly used for this purpose is calcium oxide (CaO), also known as quicklime.Calcium oxide has a strong affinity for water and can effectively absorb the water present in the rectified spirit. It reacts with water to form calcium hydroxide (Ca(OH)2), releasing heat in the process. The reaction helps to remove the remaining water content, leaving behind pure or absolute alcohol.
This question appeared on the UHS MDCAT 2015 paper, which you can sit online with every answer explained.
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About Alcohols
Alcohols contain a hydroxyl group attached to a saturated carbon atom and are classified as primary, secondary or tertiary. Their nomenclature, hydrogen bonding, acidity, oxidation, dehydration, reaction with sodium and conversion to haloalkanes are covered, along with the distinction between alcohols and phenols, where the hydroxyl group is attached directly to an aromatic ring.
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