Zadanie 3d
Wzorowane na: Chemistry HL Paper 2, May 2026, TZ1, pytanie 3(d). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 3a-3d.
Pentane, CH3CH2CH2CH2CH3, is a common fuel.
Polecenie
Pentan-2-ol will react with acidified potassium dichromate, K2Cr2O7, which is an oxidizing agent.
(i) State the name of the product of this reaction.
(ii) Explain how infrared spectroscopy could be used to distinguish between pentan-2-ol and the product in (i), referring to both structures. Use section 20 of the data booklet.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
(i) pentan-2-one ✔
(ii) pentan-2-ol shows a strong, broad absorption at 3200–3600 cm−1 AND this is O–H/alcohol
OR pentan-2-ol shows an absorption at 1050–1410 cm−1 AND this is C–O/alcohol ✔
pentan-2-one shows an absorption at 1700–1750 cm−1 AND this is C=O/carbonyl/ketone ✔
Schemat punktowania
(i) [1] pentan-2-one (accept 2-pentanone); a formula alone is not accepted because a name is asked for; pentanone without a locant, pentanal and pentanoic acid are not accepted. (ii) [2] M1: pentan-2-ol identified by its O–H (3200–3600 cm-1) or C–O (1050–1410 cm-1) absorption; M2: pentan-2-one identified by its C=O absorption (1700–1750 cm-1). Award [1 max] if only the wavenumbers of the absorptions are given, OR only the identity of the bonds present in each compound. Do not award a mark for a C–H absorption, which both compounds show.