Zadanie 16
Wzorowane na: Chemistry HL Paper 1, May 2024, TZ2, pytanie 16. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
A student determined the enthalpy change of combustion of ethanol by burning it in a spirit burner under a copper can containing 150 cm3 of water. The value obtained was less exothermic than the literature value. Which modification would improve the accuracy of the experiment?
A. Increasing the distance between the can and the flame
B. Using water that is 20 °C above room temperature at the start
C. Surrounding the burner and the can with a draught shield
D. Replacing the copper can with a glass beaker
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
C ✔
«the main error is heat lost to the surroundings instead of being transferred to the water; a draught shield reduces the loss of heat by air currents; a larger distance, warmer water and a glass beaker (a poorer conductor than copper) all increase the heat loss»
Schemat punktowania
One mark for the correct option.