Question 1: Atom economy is a measure of how efficiently a chemical reaction utilizes the reactants to produce the desired product, with minimal waste. It is especially important in space exploration where resource efficiency is crucial.

Answer: Atom economy indicates the percentage of reactant atoms that end up in the desired product, reflecting the sustainability and efficiency of the reaction.

Question 1: Define atom economy in the context of chemical reactions.

Answer: Atom economy is the ratio of the molecular weight of the desired product to the total molecular weight of all reactants, expressed as a percentage.

Question 2: Explain why high atom economy is desirable for space missions.

Answer: High atom economy reduces waste and conserves limited resources, which is vital for the sustainability and efficiency of space missions.

Question 1: A spacecraft synthesises water (H2O) by reacting hydrogen (H2) with oxygen (O2). The reaction is: 2H₂ + O₂ → 2H₂O. Calculate the atom economy for producing water in this reaction. (Atomic weights: H = 1, O = 16).

Answer: Atom economy = (Molecular weight of H₂O / Sum of molecular weights of reactants) × 100 = ((2×1 + 16) / (2×(2×1) + 16)) × 100 = (18 / 36) × 100 = 50%

Question 2: In a reaction designed to produce a lightweight fuel for spacecraft, 100 g of reactant yields 60 g of the desired product. Calculate the percentage atom economy assuming the molecular weight of the product is 50 g/mol and the total molecular weight of reactants is 120 g/mol.

Answer: Atom economy = (50 / 120) × 100 = 41.67%

Question 1: Describe a theoretical experiment to test the efficiency of a new space fuel synthesis reaction, considering variables such as temperature, pressure, and reactant purity.

Answer: The experiment would involve varying one parameter at a time (e.g., temperature), while keeping others constant, measuring the yield of the desired product, and calculating atom economy. Safety precautions include handling reactive gases in a well-ventilated area and using appropriate protective equipment.

Question 2: Explain why industries developing fuel synthesis for space missions aim to maximise atom economy.

Answer: Maximising atom economy reduces waste and resource consumption, making the process more sustainable, cost-effective, and suitable for the limited resources available in space.

Question 1: A new reaction designed for space fuel produces 80 g of desired product from 150 g of reactants. The theoretical maximum yield based on atom economy calculations is 100 g. What is the efficiency of this reaction in terms of atom economy, and what could be the reasons for any discrepancy?

Answer: Efficiency = (Actual yield / Theoretical maximum yield) × 100 = (80 / 100) × 100 = 80%. Discrepancies could be due to side reactions, incomplete reactions, or losses during purification.

Question 1: Discuss how improving atom economy in chemical reactions can benefit space agencies in terms of resource management and environmental impact.

Answer: Improving atom economy ensures that more of the reactants are converted into useful products, reducing waste and conserving limited resources in space missions. It also minimises environmental impact by decreasing the amount of hazardous waste generated, which is crucial in the closed environment of spacecraft and lunar bases. Enhanced efficiency can lead to cost savings and support sustainable exploration initiatives.