Question 1: Define a displacement reaction in the context of metals.

Answer: A displacement reaction occurs when a more reactive metal displaces a less reactive metal from its compound.

Question 2: Explain why aluminium does not easily displace hydrogen from acids.

Answer: Because aluminium forms a protective oxide layer that prevents it from reacting with acids easily.

Question 3: Describe the mechanism of a typical displacement reaction involving zinc and copper sulfate.

Answer: Zinc reacts with copper sulfate solution, displacing copper metal because zinc is more reactive, forming zinc sulfate and depositing copper metal.

Question 1: Calculate the mass of zinc required to displace 10 grams of copper from copper sulfate solution. (Molar mass of Zn = 65.38 g/mol, Cu = 63.55 g/mol, CuSO4 molar mass = 159.61 g/mol).

Answer: The molar ratio of Zn to Cu in the reaction is 1:1. Moles of Cu displaced = 10 g / 63.55 g/mol ≈ 0.157 mol. Therefore, mass of Zn = 0.157 mol × 65.38 g/mol ≈ 10.27 g.

Question 2: If 50 mL of 0.2 mol/dm³ zinc sulfate solution reacts completely with excess copper, how many grams of copper are displaced? (Molar mass of Cu = 63.55 g/mol).

Answer: Moles of Zn in 50 mL = 0.2 mol/dm³ × 0.05 dm³ = 0.01 mol. Since the reaction is 1:1, 0.01 mol of Cu is displaced, mass = 0.01 mol × 63.55 g/mol = 0.6355 g.

Question 1: Describe a basic experiment to observe a displacement reaction between magnesium and copper sulfate solution, including variables to control and safety precautions.

Answer: Set up a beaker with copper sulfate solution. Add a strip of magnesium metal. Observe the formation of copper metal on magnesium. Control variables include temperature and concentration. Safety precautions involve wearing gloves and eye protection, handling acids and metals carefully, and disposing of chemicals properly.

Question 2: Identify the independent, dependent, and control variables in a displacement reaction experiment involving zinc and copper sulfate.

Answer: Independent variable: Type of metal used (zinc). Dependent variable: Mass of copper displaced. Control variables: Concentration of copper sulfate, temperature, and reaction time.

Question 1: A student observes that when a strip of zinc is placed in copper sulfate solution, some zinc dissolves and a deposit of copper appears. The initial mass of zinc was 2.0 g, and after reaction, 1.8 g of zinc remains. Calculate the mass of copper deposited.

Answer: Mass of zinc reacted = 2.0 g - 1.8 g = 0.2 g. Moles of zinc reacted = 0.2 g / 65.38 g/mol ≈ 0.00306 mol. Since the molar ratio of Zn to Cu is 1:1, mass of Cu deposited = 0.00306 mol × 63.55 g/mol ≈ 0.194 g.

Question 1: Explain why metals like gold and platinum are rarely displaced in reactions, and discuss their uses in industry based on their reactivity.

Answer: Gold and platinum are very unreactive because they have a high resistance to corrosion and oxidation, making them stable and unlikely to be displaced. They are used in jewellery, electrical contacts, and catalytic converters due to their durability and chemical inertness.

Question 2: In the context of corrosion prevention, how does understanding displacement reactions help in selecting materials for construction?

Answer: Knowing the reactivity series helps select less reactive metals or protective coatings to prevent displacement reactions that cause corrosion, thereby increasing durability of construction materials.