Chemistry 9701/53 May June 2019 | Cambridge AS Level Past Papers With Mark Scheme

1. Manganese Ion Investigation: The experiment investigates the charge of manganese ions (Mnz+) by measuring the cell potential of an electrochemical cell. Tasks include calculating volumes, concentrations, electrode potentials, and analyzing results using the Nernst equation to determine the charge (z+) on manganese ions.
2. Preparation of Propanone from Propan-2-ol: The experiment covers the oxidation of propan-2-ol to propanone using potassium dichromate, including calculating the required mass of potassium dichromate, distillation to separate propanone, and methods to remove sulfuric acid impurities.
3. Reflux and Distillation Methods: The student uses a water bath for reflux heating and applies methods for separating propanone. The process includes theoretical and practical explanations, such as why water baths are used, and the filtration under reduced pressure for purification.
4. Titration and Filtration in Organic Chemistry: Understanding the role of filtration under reduced pressure, the drying of organic compounds, and methods for calculating percentage yields based on the mass of dry product.
5. Reactivity and Yield Calculation: Calculating the percentage yield of 2,4-DNPH derivatives and explaining reasons for less than 100% yield due to practical limitations and side reactions.
6. Experimental Improvements and Precision: Suggestions for improving the experiment's accuracy, including methods for ensuring complete drying of the product, and the rationale for using specific filtration methods to separate compounds.