Question 1: Define a mole in chemistry and explain its significance.

Answer: A mole is the amount of substance containing exactly 6.022 x 10^23 particles (atoms, molecules, or ions). It allows chemists to count particles by weighing quantities of substances.

Question 2: Describe how the concept of molar mass relates to the mole.

Answer: Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It links the mass of a sample to the number of moles it contains.

Question 1: Calculate the number of moles in 24 grams of water (H₂O). (Molar mass of H₂O = 18 g/mol)

Answer: Number of moles = mass / molar mass = 24 g / 18 g/mol = 1.33 mol

Question 2: How many molecules are present in 2 moles of sulphur dioxide (SO₂)? (Avogadro's number = 6.022 x 10^23)

Answer: Number of molecules = 2 mol x 6.022 x 10^23 molecules/mol = 1.2044 x 10^24 molecules

Question 1: Outline the safety precautions you should take when handling chemicals to measure mass in a laboratory setting.

Answer: Wear protective eyewear, gloves, and lab coat; handle chemicals carefully to avoid spills; use appropriate equipment; work in a well-ventilated area.

Question 2: Identify the independent variable, dependent variable, and control in an experiment measuring the moles of a substance produced in a reaction.

Answer: Independent variable: quantity of reactant; Dependent variable: amount of product (moles); Control: reaction conditions such as temperature and pressure.

Question 1: A sample contains 3.6 grams of carbon. Given the molar mass of carbon is 12 g/mol, calculate the number of moles present and interpret what this implies about the number of atoms.

Answer: Number of moles = 3.6 g / 12 g/mol = 0.3 mol. This means there are 0.3 mol x 6.022 x 10^23 atoms = 1.81 x 10^23 atoms of carbon.

Question 2: A chemical reaction produces 0.5 mol of a gas. Explain what this indicates about the amount of particles involved and how this relates to real-world applications such as industrial synthesis.

Answer: Producing 0.5 mol of a gas indicates that 0.5 x 6.022 x 10^23 particles are involved. In industry, controlling molar quantities allows for precise synthesis, scale-up, and safety management of chemical processes.

Question 1: Describe how the concept of moles is used in the manufacturing of pharmaceuticals.

Answer: Moles are used to measure precise amounts of reactants in drug synthesis, ensuring correct dosages and consistent quality in pharmaceutical production.

Question 2: Explain why understanding moles is crucial for environmental chemistry, such as measuring pollutant emissions.

Answer: Understanding moles allows accurate quantification of pollutants in emissions, helping regulate and reduce environmental impact through precise measurement and control.