Unit 2 🥼every day fuels 🥼

• What is the maximum ethanol concentration produced by fermentation?

  12-15%
• Why are yeast cells killed at higher ethanol concentrations?

  Because they cannot survive above 12-15% ethanol
• What process follows fermentation to produce alcoholic drinks with higher ethanol concentrations?

  Distillation
• What are the first four alcohols in the homologous series and their formulas?

  1. Methanol - CH₃OH
  2. Ethanol - C₂H₅OH
  3. Propanol - C₃H₇OH
  4. Butanol - C₄H₉OH
• What is the general formula for alcohols?

  CnH2n+1OH
• What trends are observed in the boiling and melting points of alcohols in the homologous series?

  • Boiling and melting points increase down the series
  • Due to bigger molecules
  • Stronger intermolecular forces
  • Van der Waals forces increase
• What are the common uses of alcohols?

  • Fuels
  • Food and drink
  • Disinfectants
• What is the general formula for carboxylic acids?

  CnH2n-1COOH
• What are the first four carboxylic acids and their formulas?

  1. Methanoic Acid - HCOOH
  2. Ethanoic Acid - CH₃COOH
  3. Propanoic Acid - C₂H₅COOH
  4. Butanoic Acid - C₃H₇COOH
• What happens during complete combustion of fuels?

  It occurs when something burns in a sufficient supply of oxygen
• What are the products of incomplete combustion?

  Carbon monoxide (CO) and carbon soot
• How can the heat energy released when a fuel burns be measured?

  • By measuring the rise in temperature of a known volume/mass of water
  • Calculate using the formula:

  $Eh =$$C \cdot m \cdot \Delta T$
• If you have 200 cm³ of water, what is its mass in kilograms?

  0.2 kg
• If the temperature change of water is from 50°C to 30°C, what is the change in temperature?

  20°C
• What is the specific heat capacity of water used in calculations?

  1. 18 J/g°C
• How can you reduce heat loss when measuring the energy released from burning fuels?

  Use a draught shield and a metal beaker
• If you have a temperature change of 60°C and a mass of water being heated is 0.6 kg, what is the energy released?

  $Eh =$$4.18 \times 0.6 \times 60 =$$150.48 \text{ J}$
• If the temperature change is 23.9°C, what is the energy released when heating 0.2 kg of water?

  $Eh =$$4.18 \times 0.2 \times 23.9 =$$20.00 \text{ J}$
• What are the limitations of practical determinations of energy released from burning fuels?

  • Heat loss between burning fuels and water
  • Inaccurate temperature measurements
  • Need for complete combustion
  • Use of pure oxygen for accurate results
• What is the structure of methanol?

  1. C-O-H (CH₃OH)
• What is the structure of ethanoic acid?

  1. C-C-C (CH₃COOH)
• Why is it important to ensure complete combustion in experiments?

  To accurately measure the energy released
• What is the primary alcohol present in alcoholic drinks?

  Ethanol
• What functional group do all alcohols contain?

  A hydroxyl functional group (OH)
• What is the molecular formula for ethanol?

  C₂H₅OH
• How many carbon atoms are in propanol?

  3
• What is the general formula for alcohols?

  • CₙH₂ₙ₊₁OH
• How do you name an alcohol?

  By selecting the longest carbon chain containing the hydroxyl group and naming it after the appropriate alkane
• What is the priority when numbering carbon atoms in an alcohol?

  Number from the end nearest the hydroxyl group
• What are the steps to name an alcohol?

  1. Select the longest continuous carbon chain with the hydroxyl group.
  2. Number the carbon atoms from the end nearest the hydroxyl.
  3. Number the hydroxyl and any branches.
  4. Use "di" and "tri" for multiple branches.
• How do the boiling points of alcohols change with carbon chain length?

  Boiling points increase with increasing length of carbon chain
• How does flammability change with the length of the alcohol molecule?

  Flammability decreases with increasing length of the alcohol molecule
• What products are formed when an alcohol burns in a plentiful supply of air?

  Carbon dioxide and water
• How do alcohols behave in water?

  Alcohols are soluble in water and dissolve to form solutions
• Which alcohols dissolve easily in water?

  Methanol and ethanol
• What are some uses of alcohols in everyday life?

  • Solvents in perfumes, deodorants, paints, and dyes
  • Cleaning agents in wipes and gels
  • Fuels in camping stoves and racing cars
• What is the reaction of alcohols with oxygen?

  Alcohols combust to produce carbon dioxide and water
• What is the chemical equation for the combustion of methanol?

  CH₃OH + O₂ → CO₂ + H₂O
• Why can ethanol be regarded as a renewable source of energy?

  Because it can be produced by the fermentation of sugar cane, which can be regrown
• What is Methylated Spirits commonly used for?

  As a fuel in camping stoves