Question 1: Define the Avogadro Constant in your own words.

Answer: The number of particles (atoms, molecules, or ions) in one mole of a substance, approximately 6.022 × 10^23.

Question 2: Explain why the Avogadro Constant is important in chemistry.

Answer: It allows chemists to relate the mass of a substance to the number of particles it contains, enabling calculations at the atomic and molecular level.

Question 1: Calculate the number of particles in 12 grams of carbon-12. (Atomic mass of C = 12 g/mol, Avogadro Constant = 6.022 × 10^23 particles/mol)

Answer: Number of particles = (mass / molar mass) × Avogadro Constant = (12 / 12) × 6.022 × 10^23 = 6.022 × 10^23 particles

Question 2: A sample contains 3.01 × 10^24 molecules of sulphur. How many moles does this represent?

Answer: Number of moles = number of particles / Avogadro Constant = 3.01 × 10^24 / 6.022 × 10^23 ≈ 5 mol

Question 1: Describe a simple experimental method to determine the amount of a gas produced in a reaction, using only basic laboratory equipment. Include safety precautions.

Answer: Students can set up a reaction in a sealed container connected to a gas syringe or graduated cylinder submerged in water to measure gas volume. Variables include reactant amounts and temperature. Safety precautions include wearing goggles, handling acids or reactive chemicals carefully, and ensuring proper ventilation.

Question 1: A chemist measures 24 grams of oxygen gas (O2). Given the molar mass of O2 is 32 g/mol, how many molecules are present? Show your calculation.

Answer: Number of moles = 24 / 32 = 0.75 mol; number of molecules = 0.75 × 6.022 × 10^23 ≈ 4.517 × 10^23 molecules

Question 1: Explain how the concept of the Avogadro Constant is used in industries such as pharmaceuticals or materials science. Provide specific examples.

Answer: In pharmaceuticals, the Avogadro Constant allows precise formulation of drug doses by relating mass to number of molecules, ensuring efficacy and safety. In materials science, it helps in calculating the number of atoms in a material, guiding the development of new alloys or compounds with desired properties.