Planning (a) and (b) in Chemistry Internal Assessment

The following list of investigation titles is divided into two groups:

1. experiments suitable for planning (a) and (b)
2. experiments suitable for planning (b) only.

For each title, a list of the possible variables is included. Experiments suitable for planning (a) have at least two independent variables that could be manipulated during an investigation. The titles are sufficiently specific to give candidates a sense of direction, but they are not sufficiently specific to serve as a research question. Candidates will have to modify the statement to make it more specific and focused. In most cases, this will involve indicating the variable(s) chosen for investigation. Where the title completely specifies the problem, and only one or no variables can be manipulated, the experiment is listed for planning (b) only. If the experiment is to be used to assess planning (a), candidates should not be given information about the possible variables, since one aspect of planning (a) concerns the candidate's ability to select the relevant variables without help from the teacher.

Variables are things we measure, control or manipulate in an investigation. Independent variables are those that are manipulated, whereas dependent variables are measured or registered. The variable that is selected for manipulation is independent, the variable that depends on the manipulation is dependent. Thus, in a calorimetry investigation, where a candidate measures the temperature every 30 seconds, time is the independent variable, and temperature is the dependent variable. Similarly, in a rate investigation, where the candidate measures the times taken to collect certain volumes of gas, volume is independent, and time is dependent.

Investigations Suitable for Planning (a) and (b)

Click here for a description of the planning criteria.

Note: This is a very simple experiment suitable as a first exposure to practise the skills associated with planning (a) and (b). Any of the first seven independent variables can be investigated.

Note: Suitable for practice for planning (a) and (b). Any of the independent variables could be tested.

Note: Candidates will probably control the first independent variable and can manipulate any of the last three.

Note: Temperature will probably be controlled. Any of the other independent variables can be investigated.

Note: Any of the independent variables can be easily manipulated, apart from temperature which will probably be controlled.

Note: Any of the independent variables could be investigated.

Note: Any of the first five independent variables could be manipulated, but this presents a difficult and time-consuming experiment. It would be easier for the teacher to direct the candidates to measure the amounts of acid, and to grade this for planning (b) only.

Note: Any of the independent variables could be investigated.

Note: Any of the first seven independent variables could be investigated.

Note: Any of the independent variables could be investigated. The effect of the last three is probably known in advance.

Note: Any of the first five independent variables could be investigated.

Note: Any of the first six independent variables could be manipulated.

Note: The first set of independent variables will be manipulated, and perhaps also the type of fuel. The last three independent variables will need to be controlled.

Note: Once a candidate chooses a reaction, at least two other independent variables could be manipulated.

Note: The property chosen should be one where a variable can be changed. Candidates should have to devise their own methods, rather than following familiar techniques.

Note: Several variables could be manipulated. This is a very simple variation on investigation 14 (above).

Investigations Suitable for Planning (b) Only

Note: This investigation has been listed for planning (b) only because the teacher will probably have to give information to the class about the relevant variables. This experiment has been carried out testing the possible reactions of bromine solution and the acid-catalysed addition of water to cyclohexane, cyclohexene, chlorobenzene, and methylbenzene. Any of the first four variables could be investigated.

Note: Only concentration of the solution will be varied. The challenge is to keep volumes constant by dilution in a volumetric flask, rather than dilution by adding known volumes of solvent and solution.

Note: Probably no variable will be manipulated.

Note: Probably no variable will be manipulated.

Note: This would probably be done by varying the quantity of chemical or water, and keeping other factors constant.

Note: The independent variables have to be controlled, rather than varied.

Note: One concentration can be varied while other factors are kept constant.

Note: Several factors could be varied, but they would be difficult to measure.

Note: Candidates are likely to change the first independent variable.

Note: Candidates are likely to investigate the concentration necessary for reaction.

Note: Candidates will control variables rather than manipulate them.

Note: Candidates will control variables and specify their values rather than manipulate them.

Note: Candidates will probably vary one concentration or the other, while keeping other
variables constant.

Note: In addition to the candidate work, samples submitted for moderation must include the instructions, written or oral, given to the candidate by the teacher. This vital information is used by moderators to assess whether the experiment, as given, was suitable for assessing the criteria.