Q17.
B
[1]
Q18.
(a) C6H11OH + 
6CO2 + 6H2O
1
(b) Temperature rise = 20.1
q = 50.0 × 4.18 × 20.1 = 4201 (J)
1
Mass of alcohol burned = 0.54 g and Mr alcohol = 100.0
∴ mol of alcohol = n = 0.54 / 100 = 0.0054
1
Heat change per mole = q / 1000n OR q / n
= 778 kJ mol–1 OR 778 000 J mol–1
1
ΔH = –778 kJ mol–1 OR –778 000 J mol–1
M4 is for answer with negative sign for exothermic reaction
Units are tied to the final answer and must match
1
(c) Less negative than the reference
1
Heat loss OR incomplete combustion OR evaporation of alcohol OR heat transferred to beaker not taken into account
1
(d) Water has a known density (of 1.0 g cm–3)
1
Therefore, a volume of 50.0 cm3 could be measured out
1