Question 1: Define the Avogadro Constant and state its value in particles per mole.

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

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

Answer: It allows chemists to relate the amount of substance in moles to the actual number of particles, enabling calculations of mass, volume, and number of particles in chemical reactions.

Question 3: Calculate the number of particles in 2 moles of sodium chloride (NaCl).

Answer: Number of particles = 2 mol × 6.022 × 10^23 particles/mol = 1.2044 × 10^24 particles.

Question 4: What is the significance of the Avogadro Constant in determining molar masses?

Answer: It provides a link between the mass of a substance and the number of particles it contains, allowing the calculation of molar mass from atomic or molecular masses.

Question 5: Identify the variables that need to be controlled in an experiment to determine the Avogadro Constant by counting particles in a gas.

Answer: Variables include temperature, pressure, volume, and the amount of gas in moles, to ensure accurate calculation of particle number.

Question 6: Which SI unit is used for the Avogadro Constant? A) particles per second B) particles per mole C) mol per second D) molecules per kilogram

Answer: B) particles per mole

Question 7: Fill in the blank: The Avogadro Constant is approximately ______ particles per mole.

Answer: 6.022 × 10^23

Question 8: Describe a practical method to estimate the Avogadro Constant using a crystal of aluminium.

Answer: One method involves measuring the mass and dimensions of a pure aluminium crystal, calculating its volume, and using its atomic mass and density to determine the number of atoms in the crystal. From this, the number of atoms per mole can be estimated, which reflects the Avogadro Constant.

Question 9: A scientist measures 0.5 grams of sulphur and finds it contains approximately 1.87 × 10^21 atoms. Calculate the number of atoms in 1 mole of sulphur.

Answer: Number of atoms in 1 mol = (6.022 × 10^23 atoms) (since 1 mol contains this many atoms). Given 0.5 g contains 1.87 × 10^21 atoms, so for 1 mol: (6.022 × 10^23 / 1.87 × 10^21) × 0.5 g = approximately 16.1 g per mole.

Question 10: Explain how the concept of the Avogadro Constant is applied in the pharmaceutical industry.

Answer: It helps in accurately measuring and controlling the number of molecules or ions in drug formulations, ensuring proper dosage and efficacy.