Question 1: Define an alloy and explain how it differs from a pure metal.

Answer: An alloy is a mixture of two or more elements, at least one of which is a metal, combined to improve properties. Unlike pure metals, alloys have altered strength, durability, or corrosion resistance.

Question 2: Describe the process by which an alloy is typically formed.

Answer: An alloy is formed by melting the base metal and adding other elements in specific proportions, then cooling the mixture to solidify it into a new material with enhanced properties.

Question 3: Name two common alloys and mention one key property that makes each suitable for its typical application.

Answer: Steel, which is strong and durable for construction; Brass, which is corrosion-resistant and used in musical instruments.

Question 4: Explain why alloys generally have different physical properties compared to pure metals.

Answer: Alloys have different physical properties because the addition of other elements distorts the regular metallic structure, affecting properties like strength, hardness, and corrosion resistance.

Question 1: Calculate the percentage by mass of copper in a bronze alloy containing 25 grams of tin and 175 grams of copper. Use the formula: (mass of element / total mass) × 100%.

Answer: Percentage of copper = (175 / (175 + 25)) × 100% = (175 / 200) × 100% = 87.5%

Question 2: A sample of stainless steel contains 0.08% carbon by mass. If the total mass of the sample is 2 kg, how many grams of carbon does it contain?

Answer: Mass of carbon = 0.08% of 2000 g = (0.08 / 100) × 2000 g = 1.6 g

Question 1: Describe a basic experimental procedure to produce an alloy in a school laboratory setting, including safety precautions.

Answer: To produce an alloy, first select the metals to be combined (e.g., copper and tin). Wear safety goggles and heat-resistant gloves. Melt the base metal in a crucible using a Bunsen burner or furnace. Add the other element(s) in precise proportions and stir thoroughly. Pour the molten mixture into a mould to cool and solidify. Ensure proper ventilation and handle hot materials with care.

Question 2: Identify three variables that must be controlled during alloy melting experiments and explain why.

Answer: Variables include temperature (to ensure proper melting), proportion of elements (to achieve desired properties), and stirring rate (to ensure uniform distribution). Controlling these ensures consistent and safe alloy production.

Question 1: A steel alloy used in construction is found to have a tensile strength of 600 MPa, whereas pure iron has a tensile strength of 370 MPa. Explain how alloying has affected the strength of iron.

Answer: Alloying elements like carbon and other metals create a harder and more resistant structure, increasing tensile strength compared to pure iron. The distortion of the metallic structure hinders dislocation movement, making the alloy stronger.

Question 1: Explain why stainless steel is preferred over pure iron for cutlery and kitchen equipment.

Answer: Stainless steel contains chromium which forms a protective oxide layer, making it highly resistant to corrosion and staining, unlike pure iron which rusts easily.

Question 2: Identify an industry where alloys are essential and justify their use based on properties discussed.

Answer: The aerospace industry relies heavily on high-strength, lightweight alloys like aluminium alloys and titanium alloys. These materials provide the necessary strength-to-weight ratio, corrosion resistance, and durability required for aircraft components, improving safety and fuel efficiency.