| Date | May 2013 | Marks available | 3 | Reference code | 13M.3.sl.TZ2.A2 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Describe | Question number | A2 | Adapted from | N/A |
Question
Paper chromatography is a simple method used to separate and identify the components in a mixture. To aid identification, the retention factor, \({R_{\text{f}}}\), of an unknown component can be compared with the \({R_{\text{f}}}\) values of pure samples of the possible components.
Describe how the wavelength, the frequency, and the energy, change in moving from the infrared region of the electromagnetic spectrum to the radio region of the electromagnetic spectrum.
Wavelength:
Frequency:
Energy:
Markscheme
Wavelength: increases/longer;
Frequency: decreases/lower;
Energy: decreases/lower;
Accept “weaker”.
Examiners report
The components of the double beam spectrometer seemed to be well known, though in the first part many said a monochromator “emitted” light of a single wavelength, incorrectly implying it was the light source. Many candidates knew that IR absorption depended on vibrations and polarity, though only a few gained the second mark by specifying a change in polarity. The final section appeared to well understood by candidates, with even the weakest students usually scoring full marks.
