Zadanie 2b
Wzorowane na: Chemistry HL Paper 2, May 2024, TZ2, pytanie 2(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 2a-2c.
Nitrite ions, NO2−, form when nitrogen dioxide from vehicle exhaust dissolves in alkaline surface water.
Polecenie
(i) Draw a Lewis (electron dot) structure of the nitrite ion.
(ii) Deduce the formal charges of the nitrogen atom and of both oxygen atoms, and add them to the structure you drew in (i).
(iii) Predict the shape of the ion and the size of the O-N-O bond angle.
(iv) State the hybridization state of the nitrogen atom.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) N is the central atom with one N=O double bond and one N-O single bond ✔ «one lone pair on N, two lone pairs on the double-bonded O, three lone pairs on the single-bonded O; the whole structure carries a 1− charge»
(ii) formal charge of N = 0 ✔
formal charge of the single-bonded O = −1 AND of the double-bonded O = 0 ✔
(iii) bent / angular / V-shaped ✔
any estimated bond angle in the range 110° to 119° ✔
(iv) sp2 ✔
Schemat punktowania
(i) [1]: electron pairs may be shown as dots, crosses or lines, and the resonance form with the double bond to the other oxygen is equally acceptable. A delocalized (hybrid) structure is not accepted. (ii) M1: N; M2: both oxygen atoms, consistent with the structure drawn (ECF). (iii) M1: shape; M2: angle below 120°. (iv) [1].