Zadanie 2b
Wzorowane na: Chemistry HL Paper 3, November 2024, pytanie 2(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 2a-2c.
The formula of an iron oxide can be found by reducing a weighed sample of the oxide to iron metal in a stream of hydrogen gas, H2. The empty reduction tube is weighed before the sample is added. The apparatus is shown.
Polecenie
(i) State which two further mass measurements are needed to find the oxide composition.
(ii) Outline how these measurements give the mass of oxygen removed from the sample.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) mass of the tube with the iron oxide before heating ✔
mass of the tube with the iron after reduction and cooling ✔
(ii) subtract the mass of iron from the mass of the oxide «mass lost on reduction = mass of oxygen» ✔
Schemat punktowania
(i) Apply the list principle. Accept 'mass of oxide' and 'mass of iron' if the mass of the empty tube is also given. Accept 'mass before heating' for M1 and 'mass after heating' for M2. Do not accept the mass of water formed, which is not collected in this apparatus. (ii) May be scored from the answer to (i).