3.6 Unit 6 Investigative and Practical Skills in A2 Chemistry
Candidates should carry out experimental and investigative activities in order to develop their practical skills. Experimental and investigative activities should be set in contexts appropriate to, and reflect the demand of, the A2 content. These activities should allow candidates to use their knowledge and understanding of Chemistry in planning, carrying out, analysing and evaluating their work.
The content of Units 4 and 5 provide a basis for different practical topics which may be used for experimental and investigative skills. The experience of dealing with such activities will develop the skills required for the assessment of these skills in the Unit. Examples of suitable experiments that could be considered throughout the course will be provided in the Teachers Resource Bank.
It is expected that candidates will be able to use and be familiar with standard laboratory equipment which is deemed suitable at A2 level, throughout their experiences of carrying out their practical activities.
The skills developed in the course of their practical activities are elaborated further in the How Science Works section of this specification (see Section 3.7).
In the course of their experimental work, candidates should learn to
- demonstrate and describe ethical, safe and skilful practical techniques
- process and select appropriate qualitative and quantitative methods
- make, record and communicate reliable and valid observations
- make measurements with appropriate precision and accuracy
- analyse, interpret, explain and evaluate the methodology, results and impact of their own and others experimental and investigative activities in a variety of ways.
The Centre-Assessed Option, Route T
The practical and investigative skills will be centre assessed through two methods
- Investigative Skills Assignment (ISA).
- Practical Skills Assessment (PSA).
The ISA will require candidates to undertake practical work, collect and process data and use it to answer questions in a written test (ISA test) (see Section 3.8).
The PSA will be based around a centre assessment, throughout the A2 course, of the candidate's ability to follow and undertake certain standard practical activities across the three areas of Chemistry: Inorganic, Organic and Physical.
The Externally Marked Option, Route X
The practical and investigative skills will be externally assessed through
- Practical Skills Verification (PSV) and
- Externally Marked Practical Assignment (EMPA).
The PSV will require candidates to undertake the practical activities identified on the next page, in order to gain experience of a wide range of practical skills. These activities must allow a candidate suitable opportunity to demonstrate safe and skilful practice, as well as producing reliable and valid observations.
AQA will require teacher verification, by means of a tick box on the Candidate Record Form, that a candidate is experienced in these skills.
The EMPA, in a similar way to the ISA, will require candidates to undertake practical work, collect and process data and use it to answer questions in a written test (EMPA test) (see Section 3.8).
Practical Skills Assessment
The PSA is designed to credit candidates for the practical work they undertake naturally as part of the course.
Further information is provided in Section 3.8, but it is expected that candidates will complete at least two practical activities from each of the three areas of Chemistry listed below.
A2 Inorganic Chemistry
|Carry out a redox titration||The analysis of iron tablets by titration using acidifi ed potassium manganate(VII)|
|Investigate the chemistry of transition metal compounds in a series of experiments||The chemistry of copper compounds|
|Prepare an inorganic complex||The preparation of hexaamminecobalt(III) chloride or the preparation of iron(II) ethandioate|
A2 Physical Chemistry
|Carry out a kinetic study to determine the order of a reaction||An iodine clock experiment e.g. the reaction of sulfi te ions with iodate(V) ions|
|Determine an equilibrium constant||Determine a value of Kc for the reaction of ethanol with ethanoic acid.|
|Investigate how pH changes when a weak acid reacts with a strong base or when a strong acid reacts with a weak base.||Determine the pH curve for ethanoic acid reacting with sodium hydroxide|
A2 Organic Chemistry
|Prepare a solid organic compound||The preparation of aspirin|
|Purify an organic solid||The recrystallisation of impure benzenecarboxylic acid from hot water|
|Test the purity of an organic solid||Determine the melting point of benzenecarboxylic acid|