Ethanol (Uses) MCQs Quiz | Class 10
This is a multiple-choice quiz for Class 10 Science (Code 086), focusing on Unit I: Chemical Substances – Nature and Behaviour. This quiz specifically covers the uses of Ethanol, including its roles as a solvent, fuel, and antiseptic. Attempt all questions and click ‘Submit Quiz’ to view your score, review the answers, and download a PDF of your answer sheet.
About the Uses of Ethanol
Ethanol, with the chemical formula C2H5OH, is a simple alcohol that is a volatile, flammable, and colorless liquid. It is a psychoactive substance and is the principal type of alcohol found in alcoholic beverages. Beyond this, ethanol has numerous important industrial and commercial applications due to its unique chemical properties. This section explores its key uses as a solvent, a fuel, and an antiseptic.
1. Ethanol as a Solvent
A solvent is a substance that dissolves a solute, resulting in a solution. Ethanol is an excellent solvent because its molecule has both a polar part (the hydroxyl group, -OH) and a non-polar part (the ethyl group, -C2H5). This dual nature allows it to dissolve a wide variety of substances, both polar and non-polar.
- Medicines: It is used to dissolve many drugs and compounds that are not soluble in water. A common example is ‘Tincture of Iodine,’ which is a 2-7% solution of iodine in an ethanol-water mixture, used as a mild antiseptic.
- Cosmetics and Perfumes: It serves as a base solvent in perfumes, lotions, and deodorants, helping to mix the various ingredients and aiding in their application.
- Paints and Varnishes: It is used to dissolve resins and shellac to create varnishes and lacquers.
2. Ethanol as a Fuel
Ethanol is a high-octane fuel and is increasingly used as an alternative or additive to gasoline. Since it can be produced from agricultural crops like corn, sugarcane, and wheat through fermentation, it is considered a renewable resource and is classified as a biofuel.
- Gasohol: A mixture of gasoline and ethanol (typically 10% ethanol, 90% gasoline) is sold as ‘gasohol’ or ‘E10’. This blend helps to oxygenate the fuel, leading to more complete combustion.
- Cleaner Burning: Ethanol burns more cleanly than pure gasoline. Its use reduces harmful emissions like carbon monoxide and other pollutants, making it a more environmentally friendly option.
- Energy Source: It is also used in alcohol lamps and stoves as a clean-burning fuel for heating and cooking in various settings.
3. Ethanol as an Antiseptic
An antiseptic is a substance that inhibits the growth of or destroys microorganisms on living tissue. Ethanol is widely used for this purpose due to its ability to kill germs effectively.
- Mechanism: Ethanol kills microorganisms, including bacteria, fungi, and viruses, by denaturing their essential proteins and dissolving their lipid membranes. This process disrupts their metabolism and structure, leading to cell death.
- Applications: It is the active ingredient in most hand sanitizers (usually at 60-70% concentration). It is also used in medical wipes to sterilize skin before an injection or a minor surgery and to disinfect surfaces and medical instruments.
Summary of Ethanol’s Uses
| Use | Key Property | Common Examples |
|---|---|---|
| Solvent | Ability to dissolve polar and non-polar substances | Tinctures, perfumes, varnishes |
| Fuel | High octane rating, clean combustion | Gasohol (blended with petrol), spirit lamps |
| Antiseptic | Ability to denature proteins of microorganisms | Hand sanitizers, medical wipes |
Quick Revision Points
- Ethanol is a versatile compound with major industrial uses.
- As a solvent, it is used in medicines, cosmetics, and paints.
- As a fuel, it is a renewable resource that helps reduce air pollution when blended with petrol.
- As an antiseptic, it is effective at killing germs and is a key component of sanitizers.
- The effectiveness of ethanol as an antiseptic is highest at concentrations between 60% and 90%.
Extra Practice Questions
- What is the process used to produce ethanol from sugarcane for use as a biofuel?
- Why is 100% pure ethanol not as effective as a 70% solution for antiseptic purposes?
- Explain what is meant by the ‘octane rating’ of a fuel and why ethanol is considered a high-octane fuel.
- Apart from iodine, name another substance commonly dissolved in ethanol for medical use.
- What are the by-products of the complete combustion of ethanol?
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