Question 1: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. Transition metals such as iron, platinum, and nickel are commonly used as catalysts in industry. They often work by providing an alternative pathway with lower activation energy.

Answer: A substance that speeds up a reaction without being used up; transition metals act as catalysts by lowering activation energy.

Question 1: Explain how transition metals catalyse reactions using the example of the Haber process for synthesising ammonia.

Answer: Transition metals like iron provide active sites where nitrogen and hydrogen molecules adsorb, facilitating their reaction by lowering activation energy and enabling ammonia formation.

Question 2: Describe the mechanism by which a transition metal catalyst accelerates a reaction, including adsorption and desorption steps.

Answer: The catalyst's surface adsorbs reactant molecules, weakening bonds and providing a pathway with lower activation energy. After reaction, products desorb, leaving the catalyst unchanged.

Question 1: The activation energy for a reaction without a catalyst is 150 kJ/mol. When a catalyst is used, the activation energy drops to 75 kJ/mol. Calculate the ratio of the reaction rates with and without the catalyst at 25°C (298 K). Use the Arrhenius equation approximation: Rate ∝ e^(-Ea/RT). (R = 8.314 J/mol·K)

Answer: Rate ratio = e^(-(Ea_without - Ea_with)/RT) = e^(-(150000 - 75000)/(8.314×298)) ≈ 11.6

Question 1: Design a simple experiment to test the effect of a transition metal catalyst on the rate of decomposition of hydrogen peroxide. Identify the variables involved and safety precautions you would take.

Answer: Variables: type and amount of catalyst, concentration of hydrogen peroxide, temperature. Precautions include wearing eye protection, gloves, and conducting the experiment in a well-ventilated area to avoid contact with harmful substances.

Question 1: A series of experiments measured the rate of the catalytic hydrogenation of ethene using a platinum catalyst at different temperatures. The following data was recorded: at 25°C, rate = 0.5 mol/min; at 50°C, rate = 1.2 mol/min; at 75°C, rate = 2.8 mol/min. Explain how temperature affects the reaction rate and why catalysts are important in industrial processes.

Answer: Increasing temperature increases reaction rate by providing more energy to reactant molecules. Catalysts reduce activation energy, enabling reactions to occur faster at lower temperatures, saving energy and improving efficiency.

Question 1: Identify two industrial processes that heavily rely on transition metal catalysts and describe their significance.

Answer: The Haber process for ammonia production and catalytic converters in cars. They are vital for fertiliser manufacturing and reducing vehicle emissions.

Question 2: Discuss how catalysts in catalytic converters help reduce pollution from vehicle emissions.

Answer: Catalytic converters use transition metal catalysts like platinum, palladium, and rhodium to convert harmful gases such as carbon monoxide, nitrogen oxides, and unburned hydrocarbons into less harmful substances like carbon dioxide, nitrogen, and water, thereby reducing pollution.