Question 1: Alcohols are organic compounds containing a hydroxyl (-OH) group attached to a carbon atom. They are widely used in industry and everyday life, such as in beverages, fuels, and solvents. Understanding their reactions helps in developing new materials and processes.

Answer: Alcohols are organic compounds with a hydroxyl group attached to a carbon atom, used in various applications including beverages and fuels.

Question 1: Define a primary, secondary, and tertiary alcohol.

Answer: Primary alcohol has the hydroxyl group attached to a carbon connected to only one other carbon, secondary to two, tertiary to three.

Question 2: Describe the general mechanism of the oxidation of a primary alcohol to an aldehyde and then to a carboxylic acid.

Answer: Primary alcohols undergo oxidation via a two-step process: first to aldehydes, then further oxidation to carboxylic acids, involving electron transfer and enzyme or reagent catalysis.

Question 3: Explain why methanol is considered toxic compared to ethanol.

Answer: Methanol is toxic because it is metabolised to formaldehyde and formic acid, which are harmful to cells, whereas ethanol is metabolised safely at lower concentrations.

Question 1: Calculate the number of moles in 50 grams of ethanol (C2H5OH). (Molar mass of C2H5OH = 46 g/mol)

Answer: 1.09 mol

Question 2: If a sample of methanol (CH3OH) is burned completely, producing 1.5 MJ of heat energy, how much energy is released per mole? (Molar mass of CH3OH = 32 g/mol, mass used = 16 g).

Answer: 8.4 MJ per mol

Question 1: Describe a safe method to test for the presence of a hydroxyl group in an unknown compound.

Answer: Add a small amount of potassium dichromate solution and acid; a colour change from orange to green indicates the presence of an alcohol.

Question 2: Identify the independent, dependent, and control variables in an experiment testing the boiling points of different alcohols.

Answer: Independent variable: type of alcohol; dependent variable: boiling point; control variables: pressure, amount of alcohol, container type.

Question 1: A set of alcohol samples shows the following boiling points: methanol - 65°C, ethanol - 78°C, propanol - 97°C. Explain the trend observed in boiling points with increasing molecular size.

Answer: Boiling points increase with molecular size because larger molecules have greater London dispersion forces, requiring more energy to boil.

Question 2: In a reaction, an alcohol is oxidised to a carboxylic acid. The initial mass of the alcohol was 10 g, and the final mass of the acid product was 11 g. Explain possible reasons for this mass increase.

Answer: The mass increase could be due to the addition of oxygen atoms during oxidation, or contamination with other substances, or measurement error.

Question 1: Describe the process of fermentation to produce ethanol, including key reagents and conditions. (6 marks)

Answer: Fermentation involves converting sugars into ethanol and carbon dioxide using yeast. Conditions include anaerobic environment, moderate temperature (30-40°C), and the presence of sugars like glucose. The process is catalysed by enzymes in yeast cells.

Question 2: Explain the environmental advantages of using bioethanol as a fuel compared to petrol.

Answer: Bioethanol is renewable, produces fewer greenhouse gases, and reduces reliance on fossil fuels, contributing to lower air pollution and sustainable energy production.

Question 1: Identify two industries that heavily rely on alcohols as solvents, and explain why alcohols are suitable for these applications.

Answer: Pharmaceutical and cosmetic industries use alcohols because they are effective solvents for various compounds, are volatile, and evaporate easily leaving no residue.

Question 2: Discuss how the properties of alcohols make them useful in the production of hand sanitizers.

Answer: Alcohols like ethanol and isopropanol are effective disinfectants because they denature proteins and dissolve lipids, killing bacteria and viruses; they are also volatile, aiding quick evaporation.