Zadanie 3d
Wzorowane na: Chemistry SL Paper 2, May 2022, TZ2, 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.
Methanal, HCHO, is manufactured by passing methanol vapour over a silver catalyst at a high temperature.
CH3OH(g) ⇌ HCHO(g) + H2(g) ΔH = +92 kJ mol−1
Polecenie
(i) Draw the Lewis formula of methanal.
(ii) Explain the electron domain geometry around the carbon atom in methanal.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) the carbon atom is bonded to the oxygen atom by a double bond (two shared pairs) AND to each hydrogen atom by a single bond; the oxygen atom has two non-bonding pairs ✔
(ii) three electron domains around the carbon atom «the double bond counts as one domain» ✔
the domains repel each other and are as far apart as possible / 120° apart, giving trigonal planar ✔
Schemat punktowania
(i) [1]; all valence electrons must be shown (two lone pairs on O, none on C). (ii) M1: three electron domains; M2: mutual repulsion with the resulting arrangement.