GCSE Edexcel Chemistry Combustion of alcohols: Ethanol can be used as a liquid

Question

Ethanol can be used as a liquid fuel.

A student investigates how much heat energy is released when a known mass of ethanol is burned.

The apparatus is set up as shown in Figure 15.

A known volume of water is placed in a metal can.
The temperature of the water is measured.
The ethanol is ignited and placed under the beaker so that the flame is touching the beaker.
The water is heated by the flame.
The flame is extinguished.
The final temperature of the water is measured.

Figure 15

(a) The theoretical temperature rise for burning a given mass of ethanol is 82.4 °C.

In the experiment the actual temperature rise for burning this mass of ethanol was only 34.8 °C.
One reason why the temperature rise is less than expected is that the ethanol does not burn completely.

(i) Give a reason why, even if the ethanol burns completely, the actual temperature rise is much less than the theoretical value.

Ethanol can be used as a liquid fuel - Edexcel - GCSE Chemistry - Question 10 - 2018 - Paper 1

Worked Solution & Example Answer:Ethanol can be used as a liquid fuel - Edexcel - GCSE Chemistry - Question 10 - 2018 - Paper 1

Give a reason why, even if the ethanol burns completely, the actual temperature rise is much less than the theoretical value.

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