Zadanie 37
Wzorowane na: Chemistry HL Paper 1, November 2023, TZ1, pytanie 37. 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 concentration of an ethanoic acid solution by titration against standard NaOH(aq) from a burette. Which action would introduce a systematic error?
A. Reading the burette at slightly different eye levels in each trial
B. Using a different conical flask for each trial
C. Adding a slightly different volume of distilled water to the flask in each trial
D. Rinsing the burette with distilled water only, and not with NaOH(aq), before filling it
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
D ✔
«water left in the burette dilutes the NaOH(aq) in every trial, so every titre is too large by a similar amount, a systematic error; reading at different eye levels gives random errors, and a different flask or extra water in the flask does not change the amount of acid titrated»
Schemat punktowania
One mark for the correct option.