Zadanie 8a
Wzorowane na: Chemistry HL Paper 2, May 2022, TZ2, pytanie 8(a). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 8a-8f.
Carbon occurs as several allotropes and forms an enormous variety of organic compounds.
Polecenie
(i) Outline two differences between the bonding of carbon atoms in graphite and in diamond.
(ii) Explain why fullerene, C60, sublimes at a much lower temperature than graphite.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) any two of:
graphite: each carbon atom is bonded to 3 other carbon atoms AND diamond: each carbon atom is bonded to 4 ✔
graphite: delocalized electrons AND diamond: no delocalized electrons ✔
graphite: sp² AND diamond: sp³ hybridization ✔
graphite: bond angles of 120° AND diamond: 109.5° ✔
(ii) C60 consists of separate molecules held together by weak London (dispersion) forces «which need little energy to overcome» ✔
graphite is a giant covalent structure, so many strong covalent bonds must be broken «which needs much more energy» ✔
Schemat punktowania
(i) [1] for each difference, maximum [2]; each point must compare both allotropes. (ii) M1: molecular structure with weak intermolecular forces; M2: giant covalent network with strong bonds.