Question 1: Define oxidation and reduction in terms of electron transfer.

Answer: Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 2: Explain why iron corrosion in cars is considered an example of oxidation.

Answer: Iron reacts with oxygen and water, losing electrons to form iron oxide, which is oxidation.

Question 3: Describe the role of zinc in galvanising steel car bodies.

Answer: Zinc acts as a sacrificial anode, undergoing oxidation to protect the steel from corrosion.

Question 1: Calculate the oxidation state change when iron (Fe) reacts to form Fe2O3 during rusting. Show your working.

Answer: Fe changes from 0 (elemental) to +3 in Fe2O3; each Fe atom loses 3 electrons.

Question 2: A car's catalytic converter contains platinum (Pt). If 0.5 grams of platinum catalyse the oxidation of 20 grams of carbon monoxide (CO) per hour, what is the ratio of platinum to CO in grams?

Answer: Platinum to CO ratio = 0.5 g platinum / 20 g CO = 1:40.

Question 1: Outline a procedure to determine the reactivity of zinc with hydrochloric acid, including the variables to control.

Answer: Place a known mass of zinc in hydrochloric acid, measure the amount of hydrogen gas produced over time, control temperature, acid concentration, and zinc surface area, and wear safety goggles and gloves due to corrosive acids.

Question 1: A vehicle parked in a coastal area experiences accelerated rusting of its steel components. Explain the chemical processes involved and why the rate of oxidation increases.

Answer: The presence of salt (sodium chloride) accelerates oxidation by increasing the electrochemical conductivity, facilitating electron transfer from iron to oxygen, forming rust faster.

Question 1: Discuss how catalytic converters reduce harmful emissions by involving oxidation and reduction reactions. Include specific examples of pollutants involved.

Answer: Catalytic converters facilitate oxidation of CO and unburnt hydrocarbons to CO2 and H2O, and reduction of NOx to N2 and O2, by providing surfaces where electron transfer reactions occur, thus reducing toxic emissions.

Question 2: Explain why sacrificial anodes made of zinc or magnesium are used in automotive systems to prevent corrosion.

Answer: Sacrificial anodes undergo oxidation preferentially, protecting the metal parts of the vehicle from corrosion by sacrificing themselves.