U4 AOS 3: SAC PREP

Question 1

How repeatable was the data you produced.

Answer 1

• In our experiment, we trialed each fuel/alcohol three times to assess repeatability.
• The data demonstrated high repeatability as the majority of values obtained were very similar for example the measurements for … were …, indicating consistent outcomes.

Question 2

How could the accuracy of your data be determined? Comment on the accuracy of the data and provide a reason for discrepancies.

Answer 2

• Accuracy determined by comparison to published values.
• Experimental values much lower than published [include values]
• Discrepancy most likely due to heat loss to the environment.

Question 3

List 2 sources of errors that would affect the data.

Answer 3

• Heat loss due to environment.
• Inaccurate temperature measurement as water is not homogenous.

Question 4

Comment on the validity of your experiment.

Answer 4

Experiment was valid as only one variable (type of fuel/alcohol) was changed.

Question 5

Write a conclusion to your experiment.

Answer 5

1) Aim

2) This was done by
… q=mcAt
… calculating mols burnt …
then the molar enthalpies of combustion through AHc = q/n

3) It was found that
… was highest followed by …
Much lower than published values due to heat loss (compare values)

Question 6

Comment on the precision of your data.

Answer 6

Data was precise as values between trials were relatively close the mean value of measurements.

Question 7

List two improvements to the experiment.

Answer 7

• Better insulate environment whilst allowing sufficient oxygen to flow.

Question 8

What methodology was used to perform your experiment.

Answer 8

Controlled experiment
All variables apart from the type of fuel burnt are kept constant allowing us to isolate the heat of combustion of each specific fuel.