Question 1: Define the term 'concentration' in the context of a chemical solution.

Answer: Concentration is the amount of solute present in a given volume of solvent or solution, typically expressed in molarity, grams per litre, or percentage.

Question 2: Explain why increasing the concentration of a solution can affect the rate of a chemical reaction.

Answer: Increasing concentration increases the number of particles per unit volume, leading to more frequent collisions and potentially faster reaction rates.

Question 1: Calculate the molarity of a solution prepared by dissolving 5 grams of sodium chloride (NaCl) in 250 mL of water. (Molar mass of NaCl = 58.44 g/mol).

Answer: Molarity = 0.342 mol/L

Question 2: A 0.5 M hydrochloric acid (HCl) solution contains 18.3 grams of HCl per litre. How many grams of HCl are in 250 mL of this solution?

Answer: 4.58 grams

Question 1: Describe the key safety precautions that should be taken when preparing and handling concentrated acid solutions in the laboratory.

Answer: Wear protective goggles and gloves, work in a well-ventilated area, add acid to water slowly while stirring, and handle with care to avoid spills and splashes.

Question 2: Identify the independent, dependent, and control variables in an experiment where students dilute a fixed volume of stock solution to prepare solutions of different concentrations.

Answer: Independent variable: volume of water added; Dependent variable: concentration of the diluted solution; Control variables: type of solute, initial concentration, temperature.

Question 1: A scientist prepared a solution by dissolving 10 grams of a substance in 500 mL of water. The solute has a molar mass of 50 g/mol. Calculate the concentration in mol/L and comment on whether it is a dilute or concentrated solution.

Answer: Concentration = 1.0 mol/L; It is a dilute solution because the molarity is relatively low.

Question 1: Explain why hospitals often prepare saline solutions with specific concentrations, such as 0.9% NaCl, and how this relates to maintaining a safe environment for patients.

Answer: Because 0.9% NaCl solution is isotonic with blood, preventing cell damage or dehydration, ensuring safety for intravenous administration.

Question 2: Describe how understanding solution concentration is important in industries such as pharmaceuticals or food production.

Answer: It ensures proper dosage, stability, and safety of products, and maintains consistency and quality in manufacturing processes.