Qualitative Controlled Assessment

Task Determine the order of reactivity of four metals (copper, zinc, calcium and metal M) from the observations of their reactions with a dilute mineral acid (hydrochloric or sulfuric acid) or from observations of displacement reactions using solutions of a salt of the metal and solid metal.

Planning Candidates should be given the opportunity to plan and carry out an investigation which will lead them to a reactivity series for the four metals. NB: Metal M is magnesium. Candidates should plan to carry out preliminary experiments to determine a method of judging reactivity from the chemical reactions.

Possible Methods Carry out reactions of a small quantity of the solid metal with 10 cm 3 of dilute hydrochloric acid. Carry out reactions of a small quantity of the solid metal with 10 cm 3 of dilute sulfuric acid. Carry out reactions of a small quantity of the solid metal with 10 cm 3 of solutions containing the other metal ions.

Microchemistry Metals & Acid These may be carried out on a micro-chemistry scale using spotting tiles with a very small volume (1 cm 3 ) of the acid/solution with a very small piece of the solid metal.

Microchemistry Displacement

Planning Preliminary experiments with metals Use of scientific knowledge to plan how reactions will place metals in a reactivity series Use of scientific knowledge for named metals and their reactions with air (oxygen), water and steam Hypothesis regarding three named metals and metal M based on reaction which are planned

Risk Assessment Hazard associated with metals, acids, solutions of metal salts Steps taken to minimise risk Microchemistry minimises volume of hazardous solutions used and mass of metal used

Results Simple record of observations (metal and acid) or whether reactions occur (displacement) Candidates may record observations for displacement reactions No marks awarded for results

Analysis Stating what you found out and how it matched your hypothesis Word Equation for a reaction of a named metal Balanced Symbol Equation for a reaction of a named metal Two possible sources of error and improving method to minimise error

Secondary Data Two other metals X and Y 3 results sets on reactions of X and Y X is more reactive than any of the other 4 metals Y is more reactive than copper but less reactive than Zn

Results Set A

Results Set B

Results Set C

Questions Expand reactivity series to include X and Y and explain your reasoning Which results set does not give enough information to place X in the reactivity series? Which result set is from an investigation most similar to your own? 3 Equations involving X and Y; which one would occur and explain why.