Question

Choose all correct answers and explain your reason for each
In the laboratory experimental determination of the standard heat of combustion of ethanol,
the value obtained might be (1) Lower than expected due to incomplete combustion of the
fuel (2) Lower than expected because some of the heat escape through the exhaust pipe (3)
Lower than expected because the wick of the spirit lamp also burns.

Answer 1

1) True, Fuel combustion is carried out in an air atmosphere and combustion products are not always formed .

2) True. During any thermodynamic process, there are always irretrievable losses. This, in turn, introduces certain inaccuracies in the measurement of the heat of combustion of fuel.

3) Incorrect. The wick of an alcohol lamp increases the heat effect. Instead of an alcohol lamp, an air stream or a mixture enriched with oxygen is used.