topic 7

• What are hydrocarbons composed of?

  Hydrogen and carbon atoms only
• Why is CH₃COOH not considered a hydrocarbon?

  It contains oxygen in addition to hydrogen and carbon
• What is the general formula for alkanes?

  CnH₂n+₂
• What defines alkanes as a homologous series?

  They react in a similar way
• What are the first four alkanes?

  Methane, ethane, propane, butane
• How does the length of the carbon chain affect hydrocarbon properties?

  Shorter chains are less viscous and more volatile
• What type of hydrocarbons are used as bottled gases?

  Short chain hydrocarbons
• What are the waste products of complete combustion of hydrocarbons?

  Carbon dioxide and water vapour
• What happens to carbon and hydrogen during combustion?

  They are oxidised
• Write the balanced equation for the complete combustion of methane (CH₄).

  CH₄ + 2O₂ → CO₂ + 2H₂O
• What is the difference between complete and incomplete combustion of alkenes?

  Incomplete combustion produces carbon and CO
• What is the general formula for alkenes?

  CnH₂n
• Why are alkenes considered unsaturated?

  They have a double bond between carbon atoms
• What are the first four alkenes?

  Ethene, propene, butene, pentene
• What happens during the hydrogenation of alkenes?

  They convert to saturated alkanes
• What is produced when alkenes react with water?

  An alcohol is formed
• How is ethanol industrially produced from ethene?

  By reacting ethene with steam over a catalyst
• What functional group do carboxylic acids contain?

  -COOH
• How do carboxylic acids behave in water?

  They ionise partially, making them weak acids
• What is the reaction between a carboxylic acid and a carbonate?

  Produces a salt, water, and carbon dioxide
• What is the functional group of esters?

  -COO-
• How are esters formed?

  From an alcohol and a carboxylic acid
• What is the word equation for the formation of ethyl ethanoate?

  Ethanoic acid + ethanol → ethyl ethanoate + water
• What is the significance of the C=C bond in alkenes?

  It allows for addition reactions to occur
• What color change occurs when bromine water reacts with alkenes?

  It changes from orange to colorless
• What is the result of incomplete combustion of alkenes?

  Produces carbon, carbon monoxide, and less energy
• What happens when sodium carbonate is added to methanoic acid?

  Produces a salt, water, and carbon dioxide
• What are the properties of hydrocarbons as the carbon chain length increases?

  • Shorter chains: more runny, less viscous, more volatile, more flammable
  • Longer chains: less runny, more viscous, less volatile, less flammable
• What are the reactions of alkenes?

  1. Addition reactions with hydrogen (hydrogenation)
  2. Addition reactions with water (forming alcohols)
  3. Addition reactions with halogens (e.g., bromine)
• What are the characteristics of carboxylic acids?

  • Functional group: -COOH
  • React with carbonates to produce salts, water, and CO₂
  • Weak acids that partially ionise in water
• How are esters formed from carboxylic acids?

  • Reaction between an alcohol and a carboxylic acid
  • Acid catalyst is usually required
  • General reaction: alcohol + carboxylic acid → ester + water
• What is the significance of the C=C bond in alkenes?

  • Indicates unsaturation
  • Allows for addition reactions
  • Makes alkenes more reactive than alkanes
• What is the functional group of esters?

  -COO-
• How are esters formed?

  From an alcohol and a carboxylic acid
• What is usually used as a catalyst in ester formation?

  Concentrated sulfuric acid
• What is the general reaction for ester formation?

  • Alcohol + Carboxylic Acid → Ester + Water
• What happens when carboxylic acids react in water?

  They do not ionise fully, making them weak acids
• What happens when sodium carbonate is added to methanoic acid?

  It produces carbon dioxide gas
• What is produced during a condensation reaction to form a polymer?

  A small molecule, like water
• How many products are formed by addition polymerisation?

  One product