Question 1: Explain in your own words what cracking is in the context of crude oil refining.

Answer: Cracking is a chemical process that breaks large hydrocarbon molecules in crude oil into smaller, more useful molecules such as petrol and diesel.

Question 1: What is the main difference between thermal cracking and catalytic cracking?

Answer: Thermal cracking uses high temperatures and pressures without a catalyst, while catalytic cracking uses a catalyst to lower the temperature needed and increase efficiency.

Question 2: Describe the role of a catalyst in catalytic cracking.

Answer: A catalyst speeds up the cracking reaction, allowing it to occur at lower temperatures and producing a higher yield of desired smaller hydrocarbons.

Question 1: A refinery converts 1000 kg of large hydrocarbon molecules into smaller molecules through cracking. If the average molecular weight of the large molecules is 150 g/mol and the smaller molecules have an average molecular weight of 50 g/mol, how many moles of each are produced if all large molecules are cracked completely?

Answer: Large molecules: 1000 kg / 0.15 kg/mol = 6666.67 mol; Small molecules: 6666.67 mol * (0.15 / 0.05) = 20000 mol

Question 2: If a cracking process releases 200 kJ per mole of hydrocarbon broken, how much energy is released when cracking 10,000 mol of hydrocarbons?

Answer: Energy released = 200 kJ/mol * 10,000 mol = 2,000,000 kJ

Question 1: List three safety precautions that must be taken when performing a cracking experiment in a laboratory.

Answer: Wearing protective goggles and gloves, working in a well-ventilated area or fume hood, and avoiding open flames due to flammable hydrocarbons.

Question 2: Identify the main variables that can be changed in a cracking experiment to optimize the yield of petrol.

Answer: Temperature, pressure, and type or amount of catalyst used.

Question 1: In an experiment, increasing the temperature from 500°C to 700°C increased the production of smaller hydrocarbons by 15%. Explain why temperature affects the cracking process.

Answer: Higher temperatures provide more energy to break larger hydrocarbon molecules, increasing the rate of cracking and the production of smaller hydrocarbons.

Question 1: Describe the environmental advantages of catalytic cracking over thermal cracking.

Answer: Catalytic cracking operates at lower temperatures and pressures, producing fewer pollutants such as sulfur oxides and nitrogen oxides. It also improves fuel quality and reduces waste, making it more environmentally friendly.

Question 1: Explain how cracking is essential in meeting the global demand for gasoline and diesel fuels.

Answer: Cracking breaks down large, less useful hydrocarbon molecules into smaller, more valuable fuels like gasoline and diesel, helping meet the high demand for these fuels worldwide.