Zadanie 17c
Wzorowane na: Chemistry HL Paper 3, November 2024, pytanie 17(c). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
A pharmaceutical chemist has a reference sample of the desired enantiomer of a chiral drug. Explain how a polarimeter can help establish whether a newly prepared sample contains that enantiomer.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
Pass plane-polarized light through a solution of the sample and use the analyser to measure the optical rotation ✔
Compare the direction of rotation with the desired-enantiomer reference; the opposite enantiomer gives an equal rotation in the opposite direction under identical conditions ✔
Schemat punktowania
M1: polarized light and measurement of rotation. M2: comparison with the reference, using the opposite rotations of enantiomers. Accept comparison of both sign and magnitude at the same concentration, path length, temperature and wavelength. A nonzero rotation alone does not prove enantiomeric purity.
Komentarz
The guide requires optical activity and enantiomers to be understood but does not name the polarimeter.