Zadanie 1c
Wzorowane na: Chemistry SL Paper 2, November 2022, pytanie 1(c). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 1a-1f.
Ammonium chloride, NH4Cl, is a white crystalline solid used as a nitrogen fertilizer for rice crops and as an electrolyte in dry cells.
Polecenie
Ammonium carbonate, (NH4)2CO3, is another ammonium salt; it is used in smelling salts and as a raising agent in baking. Deduce the Lewis (electron dot) structure of the carbonate ion, CO32−.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
Lewis structure with carbon bonded to three oxygen atoms: one C=O double bond and two C−O single bonds ✔
«two lone pairs on the doubly bonded oxygen and three lone pairs on each singly bonded oxygen, so that every oxygen atom has an octet»
«the whole structure in square brackets with a 2− charge, or a negative charge on each singly bonded oxygen atom»
Schemat punktowania
[1] only when the structure shows the correct bonding, all lone pairs and the 2− charge (on the square bracket or as a negative charge on the two singly bonded oxygen atoms). Accept any one of the three equivalent resonance structures. Accept dots, crosses or lines to represent electron pairs. Do not award the mark if the charge is missing.
Komentarz
The ion has 24 valence electrons (4 + 3 × 6 + 2), which is 12 electron pairs: four bonding pairs and eight lone pairs.