Question 1: The Avogadro Constant is the number of particles (atoms, molecules, or ions) in one mole of a substance. Its value is approximately 6.022 x 10^23 particles per mole. This constant allows chemists to relate microscopic particles to macroscopic measurements.

Answer: The number of particles in one mole of a substance, approximately 6.022 x 10^23.

Question 1: Define the term 'mole' in chemistry.

Answer: A unit representing 6.022 x 10^23 particles of a substance.

Question 2: Explain why the Avogadro Constant is important in converting between microscopic particles and macroscopic amounts.

Answer: It provides a bridge between the number of particles and the amount of substance in moles, allowing chemists to perform calculations involving quantities of atoms, molecules, or ions based on measurable mass.

Question 1: Calculate the number of particles in 2.5 moles of carbon atoms. (Use Avogadro Constant = 6.022 x 10^23 particles per mole.)

Answer: 1.5055 x 10^24 particles

Question 2: How many moles are there in 3.611 x 10^24 particles of sulphur atoms?

Answer: 6 moles

Question 3: A sample contains 4.81 x 10^23 molecules of water. How many moles of water does this represent?

Answer: 0.8 moles

Question 1: Describe a simple laboratory experiment to determine the molar mass of a substance using the Avogadro Constant. Include safety precautions and variables to control.

Answer: A possible experiment involves weighing a known mass of a substance, calculating the number of moles from the number of particles (using the Avogadro Constant), and then dividing mass by moles to find molar mass. Safety precautions include wearing gloves and goggles, working in a well-ventilated area, and handling chemicals carefully. Variables to control include temperature, pressure, and purity of the sample.

Question 1: A chemist measures 18 grams of water (H2O). Given that the molar mass of water is approximately 18 g/mol, calculate the number of particles of water molecules in the sample using the Avogadro Constant.

Answer: 7.48 x 10^23 particles

Question 2: In the pharmaceutical industry, precise dosing often involves calculating the number of molecules needed. Explain how the Avogadro Constant helps in this process.

Answer: It allows precise calculation of the number of molecules in a given mass, ensuring accurate dosing based on the number of particles required.

Question 3: A new technology uses nanomaterials with an average of 1 x 10^5 particles per gram. How many grams of this material are needed to obtain 6.022 x 10^23 particles?

Answer: 6.022 grams