Zadanie 1b
Wzorowane na: Chemistry SL Paper 1B, May 2026, TZ2, pytanie 1(b). 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
State two variables that should have been kept constant in the four runs.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
Any two of:
same volume and concentration of the luminol solution ✔
same volume and concentration of the hydrogen peroxide solution ✔
same size/mass of the catalyst crystal ✔
same way and same duration of stirring/mixing ✔
same distance and position of the light sensor relative to the beaker ✔
same level of surrounding light «darkened box» ✔
same time between adding the reagents and the start of recording ✔
same type and size of beaker/same volume of water in the bath ✔
same batch/age of the reagent solutions ✔
Schemat punktowania
[2 max], list principle: one mark for each of two different, correctly named variables. Temperature is the independent variable and does not score. A vague answer such as 'same amounts' without saying which reagent scores 0.