Zadanie 1a
Wzorowane na: Chemistry HL Paper 3, May 2024, TZ1, pytanie 1(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 1a-1c.
A laboratory investigation uses the oxygen released by aqueous hydrogen peroxide to follow its decomposition.
2 H2O2(aq) → 2 H2O(l) + O2(g)
For each run, a weighed portion of copper(II) oxide powder, CuO(s), is mixed with 30.0 cm3 of peroxide solution. A graduated gas syringe collects the oxygen. Readings taken at fixed time intervals give the five curves in Figure 1, each obtained with a different catalyst mass.
Polecenie
The data for 0.6 g of catalyst seem anomalous. Suggest a possible cause.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
a leak of gas from the apparatus «so less oxygen reached the syringe» ✔
OR
the volume/amount/concentration of hydrogen peroxide solution used in this run was lower than in the other runs ✔
Schemat punktowania
Award [1] for a cause that explains the lower final volume of gas, not only a slower reaction. Do not accept answers that refer to the catalyst: the catalyst is not consumed, so its mass cannot change the final volume.