Question 1: Explain in your own words what the principle of conservation of mass states during a chemical reaction.

Answer: The total mass of reactants equals the total mass of products in a chemical reaction, meaning mass is conserved.

Question 2: Why is the conservation of mass particularly important in the context of space exploration?

Answer: Because in space, mass cannot be easily gained or lost; accurate calculations of fuel and supplies depend on the conservation principle.

Question 1: Define 'mole' in the context of chemistry and explain its significance in mass calculations.

Answer: A mole is a unit that measures the amount of substance, representing 6.022 x 10²³ particles; it helps relate mass to the number of particles.

Question 2: Describe how the law of conservation of mass applies during a rocket fuel combustion process.

Answer: During combustion in a rocket, the total mass of fuel and oxidiser before ignition equals the total mass of exhaust gases and remaining substances after combustion, demonstrating mass conservation.

Question 1: A spacecraft carries 150 kg of liquid oxygen (O₂). If the molar mass of oxygen is 32 g/mol, how many moles of oxygen does it contain? (Show your calculation.)

Answer: The number of moles = (150,000 g) / (32 g/mol) = 4687.5 mol.

Question 2: During a chemical reaction in space, 10 grams of magnesium (Mg) reacts with excess hydrochloric acid. Calculate the moles of magnesium used. (Molar mass of Mg = 24.3 g/mol.)

Answer: Moles of Mg = 10 g / 24.3 g/mol ≈ 0.412 mol.

Question 1: Design a simple theoretical experiment to demonstrate the conservation of mass during a chemical reaction relevant to rocket fuel. Include at least three variables you would control.

Answer: An experiment could involve mixing a known mass of a solid fuel with oxidiser in a sealed container, then measuring the total mass before and after reaction to show it remains constant. Variables to control include temperature, pressure, and the initial masses of reactants.

Question 2: List two safety precautions that should be considered when handling reactive chemicals like fuels in space-related experiments.

Answer: Use protective equipment such as gloves and goggles; conduct reactions in well-ventilated or controlled environments to prevent accidents.

Question 1: A space mission burns 500 kg of rocket fuel, producing 480 kg of exhaust gases. Explain what this indicates about the conservation of mass in this reaction and what might account for the difference.

Answer: The slight difference suggests measurement inaccuracies or minor loss of gases to the environment; ideally, mass should be conserved, confirming the principle.

Question 1: A spacecraft's chemical reaction involves 200 g of reactant A and 150 g of reactant B. If the total mass of products is 350 g, explain whether this supports the law of conservation of mass. (6 marks)

Answer: Yes, the total mass of reactants (200 g + 150 g = 350 g) equals the mass of products (350 g), confirming the law of conservation of mass. This demonstrates that mass is neither created nor destroyed during the reaction, even in space conditions.

Question 1: How does understanding the conservation of mass help scientists calculate the amount of fuel needed for a space mission?

Answer: It allows scientists to accurately determine the total mass of reactants required, ensuring enough fuel is available for propulsion without excess or deficiency.

Question 2: Discuss how the principle of conservation of mass could influence the development of reusable rocket technologies.

Answer: Reusing rockets requires understanding that the mass of expelled gases equals the mass of fuel burned, enabling engineers to design systems that recover and refuel components efficiently. Conservation principles ensure mass balance is maintained throughout multiple launches, improving sustainability and cost-effectiveness.