Ethanol (Properties) MCQs Quiz | Class 10

This quiz focuses on Ethanol (Properties) from Class X Science (Code 086), Unit I: Chemical Substances – Nature and Behaviour. Test your understanding of ethanol’s physical and chemical properties, including its miscibility and flammability. Complete the quiz to see your score and download a detailed PDF of your answers.

Understanding Ethanol: Properties and Reactions

Ethanol (C2H5OH), commonly known as ethyl alcohol, is a key organic compound with a wide range of applications. Its unique properties are due to the presence of the hydroxyl (-OH) functional group, which makes it distinct from hydrocarbons.

Key Properties of Ethanol

Understanding ethanol’s characteristics is crucial for its safe handling and diverse uses.

1. Physical Properties

  • State: Ethanol is a colorless liquid at room temperature.
  • Smell: It has a characteristic alcoholic smell.
  • Boiling Point: Its boiling point is relatively low (approx. 78 degrees C), lower than that of water (100 degrees C).

2. Miscibility

  • Water Miscibility: Ethanol is completely miscible with water in all proportions. This means it can dissolve in water in any amount without forming separate layers. This property is due to the formation of hydrogen bonds between ethanol and water molecules.

3. Flammability

  • Highly Flammable: Ethanol is a highly flammable substance. It readily catches fire and burns with a clean, blue flame.
  • Combustion Reaction: The complete combustion of ethanol produces carbon dioxide and water vapor: 
    C2H5OH + 3O2 → 2CO2 + 3H2O

4. Chemical Properties

  • Reaction with Sodium: Ethanol reacts with active metals like sodium to produce sodium ethoxide and hydrogen gas. This reaction demonstrates the acidic nature of the hydrogen atom in the hydroxyl group, although ethanol is generally considered neutral. 
    2C2H5OH + 2Na → 2C2H5ONa + H2
  • Dehydration of Ethanol: When ethanol is heated with concentrated sulfuric acid at 443 K (170 °C), it undergoes dehydration, losing a water molecule to form ethene (an alkene). Concentrated sulfuric acid acts as a dehydrating agent here. 
    C2H5OH --(Conc. H2SO4, 443K)--> C2H4 + H2O
  • Oxidation of Ethanol: Ethanol can be oxidized to ethanoic acid (acetic acid) using strong oxidizing agents such as acidified potassium dichromate (K2Cr2O7) or alkaline potassium permanganate (KMnO4). 
    C2H5OH --(Oxidation)--> CH3COOH
  • Neutral Nature: Ethanol is a neutral compound. It does not change the color of litmus paper, indicating it is neither acidic nor basic.

Common Applications of Ethanol

Due to its versatile properties, ethanol finds use in various fields:

Application Description
Solvent Used to dissolve many organic compounds in medicines, perfumes, and varnishes.
Fuel Blended with petrol (gasoline) to form gasohol, used as a biofuel.
Antiseptic Used in hand sanitizers and medical wipes to kill microorganisms.
Preservative Used to preserve biological specimens.
Beverage The intoxicating ingredient in alcoholic drinks.

Quick Revision Points

  • Ethanol’s chemical formula is C2H5OH.
  • It is a colorless liquid with a characteristic smell and a boiling point of 78°C.
  • Ethanol is completely miscible with water.
  • It is highly flammable and burns with a blue flame to produce CO2 and H2O.
  • It reacts with sodium to form sodium ethoxide and hydrogen gas.
  • Dehydration of ethanol with concentrated H2SO4 forms ethene.
  • Oxidation of ethanol yields ethanoic acid.
  • Ethanol is neutral towards litmus.

Extra Practice Questions

  1. What is the chemical formula of ethanol?
  2. Is ethanol acidic, basic, or neutral to litmus paper?
  3. Name the gaseous product formed when ethanol reacts with sodium metal.
  4. Write the balanced chemical equation for the complete combustion of ethanol.
  5. What is the specific role of concentrated sulfuric acid when ethanol is converted to ethene?