Question 1: Explain the principle behind chromatography and how it is used to determine the purity of a substance.

Answer: Chromatography separates the components of a mixture based on their different affinities for a stationary phase and a mobile phase, allowing identification and purity assessment.

Question 1: Define the stationary phase and the mobile phase in chromatography.

Answer: The stationary phase is the phase that remains fixed inside the chromatography apparatus, while the mobile phase is the liquid or gas that moves through or over the stationary phase carrying the mixture components.

Question 2: Describe how different substances in a mixture travel through the stationary phase at different rates.

Answer: Different substances have varying affinities for the stationary and mobile phases. Substances with a higher affinity for the mobile phase move faster, while those that interact more with the stationary phase move slower, leading to separation.

Question 1: Calculate the Rf value for a substance that travels 3.5 cm in the mobile phase, while the solvent front travels 10 cm. Use the formula Rf = distance traveled by substance / distance traveled by solvent front.

Answer: 0.35

Question 1: List three variables that can affect the separation of components in a chromatography experiment.

Answer: The choice of stationary and mobile phases, the flow rate of the mobile phase, and the temperature of the environment.

Question 2: State two safety precautions that should be taken when conducting chromatography experiments in the laboratory.

Answer: Wear appropriate protective equipment such as gloves and goggles, and handle solvents in a well-ventilated area to avoid inhalation of fumes.

Question 1: In a chromatography experiment, a dye mixture was separated, and the following Rf values were observed: Red dye - 0.8, Blue dye - 0.4, Green dye - 0.6. Which dye is most soluble in the mobile phase? Justify your answer.

Answer: The Red dye is most soluble in the mobile phase because it has the highest Rf value, indicating it traveled the farthest relative to the solvent front.

Question 1: Explain why chromatography is considered a useful technique for analyzing the purity of a substance. (6 marks)

Answer: Chromatography allows for the separation of different components within a mixture, making it possible to identify impurities or confirm purity. It is sensitive, can analyze complex mixtures, and provides visual evidence of the number of components present, making it a valuable tool in quality control and chemical analysis.

Question 1: Describe how chromatography is used in the food industry to ensure the safety and quality of products.

Answer: Chromatography is used to detect and quantify additives, contaminants, and flavor compounds in food products, ensuring they meet safety standards and quality specifications.

Question 2: Explain the importance of chromatography in the development of new pharmaceuticals.

Answer: Chromatography is crucial for purifying compounds, analyzing drug components, and verifying the composition and purity of pharmaceuticals, ensuring their safety and efficacy.