Zadanie 20
Wzorowane na: Chemistry HL Paper 1, May 2022, TZ1, pytanie 20. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
The table shows initial rate data for the hydrolysis of a tertiary halogenoalkane, RBr, with aqueous sodium hydroxide at constant temperature.
| [OH−] / mol dm−3 | [RBr] / mol dm−3 | Initial rate / mol dm−3 s−1 |
|---|---|---|
| 0.10 | 0.020 | 3.0 × 10−6 |
| 0.20 | 0.020 | 3.1 × 10−6 |
| 0.20 | 0.040 | 6.1 × 10−6 |
Which statements are correct?
I. The reaction is first order with respect to hydroxide ions.
II. The reaction is first order overall.
III. The reaction proceeds by an SN1 mechanism.
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
C ✔
«doubling [OH−] at constant [RBr] leaves the rate unchanged (zero order in OH−, so I is false); doubling [RBr] doubles the rate (first order in RBr), so the reaction is first order overall; a rate that depends only on the halogenoalkane concentration fits the two-step SN1 mechanism of a tertiary halogenoalkane»
Schemat punktowania
One mark for the correct option.