Zadanie 6b
Wzorowane na: Chemistry HL Paper 3, November 2023, TZ1, pytanie 6(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 6b-6c.
A biochemist is analysing a protein extracted from soya beans.
Polecenie
A sample of the protein is completely hydrolysed to a mixture of amino acids. Outline how paper chromatography can be used to identify the amino acids in this mixture when samples of the pure amino acids are available for comparison.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
Any three of:
spot the mixture and the pure amino acids on the baseline of the chromatography paper/stationary phase ✔
place the paper in the solvent/mobile phase and let the solvent rise up the paper ✔
the amino acids separate because they differ in their attraction to/solubility in the mobile phase and the stationary phase/paper OR because of differences in polarity ✔
make the colourless spots visible with a locating agent «e.g. ninhydrin» OR UV light ✔
calculate the Rf/retention factor of each spot ✔
compare the Rf values/positions of the spots with those of the pure amino acids ✔
Schemat punktowania
Any three marking points. The Rf value must be stated explicitly, or the spots must be compared with known samples run on the same paper. No marks for separation based on charge in an electric field (electrophoresis). Knowledge of a locating agent is not required for full marks.