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

Answer: A mole is the amount of a substance that contains exactly 6.022 x 10^23 particles (atoms, molecules, ions). It provides a bridge between atomic-scale particles and macroscopic quantities, allowing chemists to measure and compare amounts of substances easily.

Question 2: Calculate the molar mass of water (H₂O). Show your working.

Answer: Molar mass of H₂O = (2 x 1.008 g/mol) + (16.00 g/mol) = 18.016 g/mol.

Question 3: If you have 36.032 grams of water, how many moles of water are present? Use the molar mass provided.

Answer: Number of moles = mass / molar mass = 36.032 g / 18.016 g/mol = 2 moles.

Question 4: What are the key particles counted when using a mole? List at least three.

Answer: Atoms, molecules, and ions.

Question 5: A scientist measures 0.5 moles of sodium chloride (NaCl). What is the total number of formula units of NaCl present? (Use Avogadro's number: 6.022 x 10^23).

Answer: Total formula units = 0.5 mol x 6.022 x 10^23 = 3.011 x 10^23 units.

Question 6: Multiple Choice: Which of the following best describes the concept of a mole?

Answer: B) A specific number of particles, 6.022 x 10^23.

Question 7: Fill in the blank: To convert grams to moles, you divide the mass of the substance by its ________.

Answer: molar mass

Question 8: Explain why the concept of moles is important in chemical reactions and industry.

Answer: The concept of moles allows chemists to quantify and predict the amounts of reactants and products involved in chemical reactions. This is essential in industry for scaling reactions, ensuring safety, optimizing yields, and reducing waste. It provides a standardized way to communicate quantities across different contexts, facilitating precise and efficient chemical manufacturing.

Question 9: Describe a simple experiment to determine the number of moles in a given sample of a solid substance. Include the key steps and safety precautions.

Answer: First, measure the mass of the solid using a balance. Record the mass accurately. Calculate the molar mass of the substance. Divide the measured mass by the molar mass to find the number of moles. Safety precautions include wearing gloves and goggles, handling chemicals carefully, and ensuring the workspace is clean and well-ventilated.

Question 10: A company manufactures sulfuric acid (H₂SO₄). If they produce 98 grams of H₂SO₄, how many moles are produced? (Molar mass of H₂SO₄ = 98.079 g/mol).

Answer: Number of moles = 98 g / 98.079 g/mol ≈ 1 mol.

Question 11: In everyday life, why is understanding the concept of moles useful when cooking or baking?

Answer: Understanding moles helps in accurately measuring ingredients in terms of chemical quantities, which can improve consistency and safety in recipes, especially in scientific or industrial food production.