Zadanie 8a
Wzorowane na: Chemistry HL Paper 3, May 2023, TZ1, pytanie 8(a). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 8a-8b.
Amino acids can be separated by paper chromatography. A student spotted a mixture of amino acids on the origin line of a strip of chromatography paper and developed the chromatogram with a mixture of butanol and ethanoic acid as the mobile phase. The table gives the RF values of some amino acids in this system.
| Amino acid | RF value |
|---|---|
| Lysine | 0.14 |
| Aspartic acid | 0.24 |
| Asparagine | 0.25 |
| Alanine | 0.38 |
| Proline | 0.43 |
| Valine | 0.61 |
| Phenylalanine | 0.68 |
| Leucine | 0.73 |
The developed chromatogram is shown with a ruler scale in centimetres, whose zero is level with the origin line. Measure to the centre of each spot.
Polecenie
Determine the identity of the amino acid in spot B by calculating its RF value from the chromatogram.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
distance moved by spot B = 7.3 cm AND distance moved by the solvent front = 12.0 cm
«» 0.61, so spot B is valine ✔
Schemat punktowania
Award [1] for valine with a supporting calculation. Accept distances read as 7.2 cm to 7.4 cm and an RF value of 0.60 to 0.62.