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CHEMISTRY, M4 EQ-Bank 25

In an experiment, 1.40 g of pure sucrose, , underwent complete combustion, heating 350 mL of water from 19.6 °C to 35.8 °C.

= 342 g mol

Assuming there was no heat lost to the surroundings, calculate the experimental heat of combustion of pure sucrose, in joules per gram.   (2 marks)

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CHEMISTRY, M4 2017 VCE 23 MC

The heat of combustion of a sample of crude oil is to be determined using a bomb calorimeter. All of the students in a class are given the same method to follow. The apparatus used by the students is shown below.
 

For this experiment, the students could maximise

  1. precision by using a digital thermometer 0.2 °C.
  2. validity by calculating the heat of combustion per mole.
  3. accuracy by taking samples from three different sources.
  4. uncertainty by having all students closely follow the same experimental procedure.
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Consider each option:

→ Option A: Error involved in reading the thermometer would be improved by this measure.

→ Option B: Energy per mole is inappropriate as crude oil is used.

→ Option C: Accuracy dependent on process technique, not the source of samples.

→ Option D: If the procedure itself creates inaccuracy, this is incorrect. 

♦ Mean mark 49%.