Zadanie 1d
Wzorowane na: Chemistry HL Paper 1B, May 2026, TZ2, pytanie 1(d). 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-1h.
A student investigated how temperature affects the intensity and the duration of the light given out when alkaline luminol solution reacts with hydrogen peroxide in the presence of a catalyst, hexacyanoferrate(III) ions.
Four beakers, each holding 50.0 cm3 of the same alkaline luminol solution, were placed one at a time in a water bath inside a darkened box, the bath being at a different temperature for each run. In every run, 10.0 cm3 of hydrogen peroxide solution and one small crystal of the catalyst were added and the mixture was stirred once. A light sensor beside the beaker recorded the light intensity every 30 seconds for 60 minutes.
The results are shown on the graph. Each curve is labelled with the temperature of the water bath.
Polecenie
Suggest why the light intensity rose during the first minutes of each run.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
the added hydrogen peroxide solution and catalyst, which started at laboratory temperature, needed time to reach the temperature of the water bath ✔
OR
the catalyst/reactants had not yet dissolved and mixed fully «after one brief stir» ✔
Schemat punktowania
[1] for either explanation. An answer that only describes the shape of the curve scores 0.
Komentarz
The sensor measures the rate at which light is emitted, so the rise reflects the time the system took to settle, not an increase in the amount of reactant.