Zadanie 38
Wzorowane na: Chemistry HL Paper 1, May 2023, TZ2, pytanie 38. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
A student determines the formula of hydrated copper(II) sulfate, CuSO4 ⋅ x H2O, by heating a weighed sample until its mass is constant. Which observation would explain a systematic error in the value of x?
A. The crucible was always weighed while it was still warm, so every balance reading was too low
B. The student misread the balance display once during one of the weighings
C. The size of the crystals differed slightly between repeat samples
D. A draught made the last digit of the balance reading fluctuate
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
A ✔
«a systematic error shifts all results in the same direction by a similar amount; weighing a warm crucible gives a low reading every time because of convection currents, whereas a single misread value, differences between samples and a fluctuating reading are random errors or mistakes that vary from trial to trial»
Schemat punktowania
One mark for the correct option.