Chemistry 9701/51 Oct Nov 2014 | Cambridge AS Level Past Papers With Mark Scheme

1. Analytical procedure for confirming solder composition (Zn, Al, Cu) using sequential extraction with sulfuric acid and ammonia, and steps for separating hydroxides by filtration.
2. Justifications for reagent quantities in each extraction step based on stoichiometry and reaction specificity to ensure complete separation and avoid excess.
3. Conversion of aluminum and zinc hydroxides into oxides by heating, with methodology to verify complete thermal decomposition.
4. Calculation of aluminum mass from aluminum oxide yield, with molar mass relationships and stoichiometric principles applied to confirm solder composition.
5. Titration curve plotting for weak monoprotic acid neutralization with NaOH, identifying equivalence point pH ranges for indicator selection and anomalous data points.
6. Calculations of acid dissociation constant (Ka) and molecular mass determination of the acid (HA), using pH data and initial conditions, addressing potential experimental errors affecting molecular mass accuracy.