Today we will look at Design aspect 1.
This criteria is really split into two parts – the research question and the variables.
To obtain a ‘c’, the student needs to produce a focused research question. A research question along the lines of ‘How does concentration effect cell voltage?’ would not be considered focused enough – this would be awarded a ‘p’.
A more focused question would talk about ‘How do concentrations of 0.1, 0.2, .0.3, 0.4 and 0.5 mol dm-3 copper sulfate / copper half cell effect the voltage generated in a cell coupled to zinc / zinc sulfate (1.0 mol dm-3) at 25oC’.There should be no reason why this question does not get a ‘c’.
The dependant and independent variable should be clearly stated. This is usually done well. However, the control variable should also be listed and this is often only glossed over by students – in order to achieve a ‘c’ the student must really pay close attention to detail.
The control variable should be a comprehensive but realistic list. It would not be wrong to mention carrying out the lab at constant pressure but in this example, would this really be appropriate?
In the above type of lab, students should go as far as mentioning details such as ensuring the surface area of the electrodes are the same and controlled, as well as ensuring that the area of electrode in contact with the solution is also controlled. This type of detail should ensure a ‘c’ is awarded.
In oder to achieve a ‘c’ overall, both of these ‘sub aspects’ should be of ‘c’ quality.
Please feel free to post any questions you have on Design, aspect 1 below.