Zadanie 1b
Wzorowane na: Chemistry HL Paper 2, May 2026, TZ2, pytanie 1(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
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Polecenie
Sulfapyridine is an antibacterial drug. Its structure is shown below.
C11H11N3O2S
Mr = 249.32
(i) Deduce the hybridization of the nitrogen atom that is part of a ring.
(ii) Describe how the sigma (σ) and pi (π) components of an S=O bond in sulfapyridine are formed.
(iii) Deduce how many signals appear in the 1H NMR spectrum of sulfapyridine and the relative areas of those signals.
(iv) Calculate the mass percentage of nitrogen in sulfapyridine. Use section 7 of the data booklet.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
(i) sp2 ✔ «three electron domains on the ring nitrogen: two sigma bonds to carbon atoms and a lone pair; the fourth orbital is an unhybridized p orbital in the pi system»
(ii) sigma (σ) bond: head-on overlap / combination of atomic orbitals «of S and O, along the bond axis» ✔
pi (π) bond: lateral / sideways overlap / combination of p orbitals «of S and O» ✔
(iii) Number of signals: 8 ✔
Relative areas: 2 : 2 : 2 : 1 : 1 : 1 : 1 : 1 «two kinds of benzene ring H, 2 H each; NH2, 2 H; NH, 1 H; four different ring H on the pyridine ring, 1 H each; in any order» ✔
(iv) «» 16.86 «%» ✔
Schemat punktowania
(i) [1] sp2. (ii) [2] M1 sigma bond: head-on overlap of orbitals; M2 pi bond: sideways overlap of p orbitals; accept suitable diagrams. (iii) [2] M1 eight signals; M2 relative areas, accepted in any order. (iv) [1] 16.86 %; accept 16.9 %.
Komentarz
In (iii) the hydrogen atoms on nitrogen give signals of their own, so NH2 and NH are counted separately, and the four hydrogens on the pyridine ring are all in different environments.