Carbon and its Compounds

• Combustion of carbon compounds in the air gives carbon dioxide, water, heat, and light
• Saturated hydrocarbons burn with a blue flame in the presence of a sufficient supply of air or oxygen
• Unsaturated hydrocarbons burn with a yellow smoky flame
• Alcohol (saturated compound) produces no smoke when burned
• Naphthalene and Camphor (unsaturated compounds) produce smoke when burned
• Saturated hydrocarbons give a clean flame, while unsaturated carbon compounds give a yellow flame with black smoke
• Yellow, sooty flame is obtained when the air hole at the end of the bunsen burner is completely closed
• Blue flame is produced when the air hole at the bottom of the bunsen burner is open and the carbon fuel is supplied with enough oxygen for complete combustion
• Alkaline potassium permanganate acts as an oxidising agent
• Oxidation of ethanol in the presence of oxidising agents gives ethanoic acid
• Alkaline potassium permanganate and acidified potassium dichromate are oxidising agents
• Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons
• Chlorine can replace hydrogen atoms in hydrocarbons in the presence of sunlight, known as a substitution reaction
• Ethanol is commonly called alcohol and is the active ingredient of all alcoholic drinks
• Ethanol is a good solvent and is used in medicines such as tincture iodine, cough syrups, and tonics
• Pure ethanol is called absolute alcohol and intake of even a small quantity can be lethal
• Consumption of large quantities of ethanol can lead to lack of coordination, mental confusion, and depression of the central nervous system
• Methanol is oxidised to methanal in the liver and can cause blindness
• Sugarcane juice can be fermented to give alcohol (ethanol) which is used as a cleaner fuel additive in petrol
• Alcohols react with sodium leading to the evolution of hydrogen and the formation of sodium ethoxide
• Alcohols react with sodium to produce hydrogen and sodium ethoxide
• Ethanoic acid reacts with sodium to produce hydrogen and sodium ethanoate
• Heating ethanol with concentrated sulphuric acid at 443 K results in the dehydration of ethanol to give ethene
• Concentrated sulphuric acid acts as a dehydrating agent that removes water from ethanol
• Properties of Ethanoic Acid:

  • Molecular formula: C2H4O2
  • Functional group: Carboxylic group (-COOH)
  • Molecular mass: 60u
  • Melting point: 290 K, known as glacial acetic acid
  • Ethanoic acid is commonly called acetic acid and belongs to carboxylic acids
  • 5-8% solution of acetic acid in water is vinegar, used as a preservative
  • Ethanoic acid is a weak acid, turning blue litmus red
• Esterification reaction:

  • Ethanoic acid reacts with ethanol in the presence of an acid catalyst to give ethyl ethanoate
  • Esters are used in perfumes and as flavoring agents
• Saponification:

  • Ester is converted back to alcohol and sodium salt of carboxylic acid with sodium hydroxide
  • Used in soap preparation
• Ethanoic acid reacts with a base like sodium hydroxide to give sodium ethanoate and water
• Ethanoic acid reacts with carbonates and hydrogen carbonates to give sodium acetate, carbon dioxide, and water
• Soaps and Detergents:

  • Soaps are sodium or potassium salts of long-chain carboxylic acids
  • Soaps interact with oil and water to form micelles for cleaning
  • Micelles are not formed in solvents like ethanol
  • Scum forms when hard water reacts with soap due to calcium and magnesium salts
  • Agitation is necessary to remove micelles and dirt from clothes
  • Detergents do not form insoluble precipitates in hard water, making them effective cleaners
  • Detergents are better cleansing agents than soaps as they work in both hard and soft water