Zadanie 16e
Wzorowane na: Chemistry HL Paper 3, November 2023, TZ1, pytanie 16(e). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
A tablet contains either aspirin or paracetamol as its active ingredient. The structures of the two compounds and the IR spectrum of the active ingredient are shown.
Deduce whether the active ingredient is aspirin or paracetamol, and give two reasons that refer to the structures and the spectrum. Use section 20 of the data booklet.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
aspirin AND any two of:
a strong absorption between 1700 and 1750 cm⁻¹ shows the C=O of an ester/carboxylic acid group ✔
a very broad absorption between 2500 and 3000 cm⁻¹ shows the O–H of a carboxylic acid group, present in aspirin but not in paracetamol ✔
no strong, broad absorption centred within 3200–3600 cm⁻¹, so no phenol O–H «or N–H» group, which paracetamol has ✔
Schemat punktowania
No marks if paracetamol is chosen; naming aspirin alone earns nothing. M1 and M2: any two of the three spectral reasons, each linked to a group in the structure. Accept any value within the quoted ranges.
Komentarz
Aspirin has no phenol O–H group because the phenol oxygen is acetylated, so there is no strong band centred in the 3200–3600 cm⁻¹ region. The amide C=O of paracetamol absorbs below 1700 cm⁻¹, so a strong band between 1700 and 1750 cm⁻¹ also points to aspirin.