Zadanie 9b
Wzorowane na: Chemistry HL Paper 2, May 2023, TZ1, pytanie 9(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
Bromine radicals form when the bond in a bromine molecule is broken by ultraviolet light. The energy needed to break the bond in one molecule of Br2 is 3.21 × 10−19 J.
(i) Calculate the minimum frequency of light needed to break this bond. Use sections 1 and 2 of the data booklet.
(ii) Calculate the formal charge on each atom in the two Lewis structures of sulfur dioxide, SO2.
Give the formal charge on oxygen 1, sulfur and oxygen 2 for structure A and for structure B.
(iii) Lewis structure A obeys the octet rule for every atom and is sometimes said to be the more stable. Suggest, giving one reason, whether the formal charge model supports this.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) «» 4.84 × 1014 Hz ✔
(ii) structure A: oxygen 1 = 0, sulfur = +1, oxygen 2 = −1; structure B: oxygen 1 = 0, sulfur = 0, oxygen 2 = 0 ✔
(iii) no AND structure B has a formal charge of zero on all atoms «the model favours B, whereas A has charges of +1 and -1» ✔
Schemat punktowania
(i) [1]: accept 4.84 × 1014 s−1. (ii) [1]: all six values correct. (iii) [1]: 'no' and the reason are both needed.