Zadanie 3b
Wzorowane na: Chemistry SL Paper 3, November 2023, TZ1, pytanie 3(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
The properties of a material depend on the way its atoms are bonded and arranged.
Sheets of pyrolytic graphite, which consists of many stacked layers of carbon atoms, are used in some phones to spread heat away from the processor. A sheet conducts heat very well parallel to its surface but poorly through its thickness.
Suggest an explanation, in terms of bonding and electrons, for the difference in conduction of heat between the two directions.
Parallel to the layers:
Perpendicular to the layers:
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
Parallel to the layers:
delocalized electrons move freely within a layer
OR
carbon atoms within a layer are covalently bonded/in contact with each other ✔
Perpendicular to the layers:
delocalized electrons do not extend/move from one layer to the next
OR
atoms in neighbouring layers are not bonded, the layers being held together only by weak London/dispersion forces ✔
Schemat punktowania
M1: an explanation for the parallel direction. M2: an explanation for the perpendicular direction. Each explanation must refer to electrons or to bonding; 'graphite is layered' alone earns nothing.