Zadanie 20b
Wzorowane na: Chemistry HL Paper 3, May 2024, TZ2, pytanie 20(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 20a-20b.
Propan-1-ol can be oxidized first to propanal and then to propanoic acid.
Polecenie
A sample is known to be either propan-1-ol or propanoic acid. Its 1H NMR spectrum is shown.
(i) Deduce, giving a reason, whether the sample is propan-1-ol or propanoic acid. Use section 21 of the data booklet.
(ii) Predict, giving a reason, the splitting pattern of the signal produced by the hydrogen atoms in the methyl group of propanal, CH3CH2CHO.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) propanoic acid AND any one of:
a signal at about 11.6 ppm/in the range 9.0–13.0 ppm for the RCOO–H proton ✔
OR
no signal at 3.3–3.7 ppm for −CH2−O− ✔
OR
three signals «not the four expected for propan-1-ol» ✔
(ii) triplet AND the neighbouring CH2 group has two hydrogen atoms «n + 1 = 3» ✔
Schemat punktowania
(i) [1]: the identity with one correct reason read from the spectrum. (ii) [1]: the pattern with the reason; "triplet" alone earns nothing.