Having just, as I write this in late July, finished six days of awarding A level exams, I am amazed still at the often poor quality of diagrams that I see from students who are supposed to have had more practical experience than ever before. Sorry, but its true. The candidate who can draw a good, working fractional distillation apparatus is still the exception. Such easy marks, too . The rest of the work is often good, can even be excellent, so it isn't a matter of not being able to do Chemistry.
Its so easy to do something about your drawing if its poor:
- You have to mind that its poor and be prepared to do something about it.
- You have to be aware of the function of each piece of apparatus, so that you dont produce a diagram of apparatus that could not work in principle.
- You have to look in detail at the apparatus that you use during your course and draw it accurately and carefully.
- Practice drawing it until its right.
- Learn it.
The drawings presented here are not supposed to be fantastically beautiful; rather they do the job. That job is to show someone else how to assemble the apparatus from standard glassware. They were drawn in pen. They would get full marks in an exam.
Hints for good diagrams.
- Draw diagrams in section, not as 3D pictures.
- Start at the top and work down, so that you are less likely to run out of space.
- Make the drawing big enough to see the detail, but not enormous. In an exam you will often have a limited space, so plan your drawing before you begin it.
- Draw in whatever medium you prefer.
- Do not show Bunsen burners, or the bench, or gas taps, or clamps. All these are common enough to be understood.
- A water or oil heating bath should be shown if used.
- Label important points or unusual items.
- Remember the function of each part of the apparatus as you draw it.
- Do not invent weird pieces of glassware. All A level work can be done in standard laboratory glassware.
- If you name the glassware, use proper names. A round-bottomed flask is not a conical flask or a beaker.
Dr Rod Beavon 17 Dean's Yard London SW1P 3PB
Chemistry Contents Simple distillation Fractional distillation Reflux Gas preparation
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