Here is the MODEL write up, which Mr. Hall did, of your experiment into the solubility of an ionic substance. The NOTES underneath each section refer to Science Criterion Sheet D and Science Criterion Sheet E.



CONCLUSION[AA1] :
The graph suggests that there is no relationship between temperature and solubility. [AA2] However, there is limited data (4 points) and it is possible that there are anomalous points. The data is not reliable. [AA3] Our experiment shows that temperature does not affect solubility in a predictable manner; perhaps a slight increase as the temperature rises. The higher temperatures help to break the bonds holding the ions together.[AA4]
The data is insufficient to support the hypothesis.


[AA1]see
CRITERIA SHEETS – D&E
[AA2]Identify + Describe trend/pattern in data
[AA3]comment on reliability of data
[AA4]+ draw a clear conclusion based on interpretation of data

EVALUATION:
We used small masses of solution, for example 0.1g. The inaccuracy of the balance is ±0.01, this gives a percentage inaccuracy of 0.01/0.12 x 100 = 10%.
The typical solute mass was 0.05g. This gives a percentage error of 0.01/0.05 x 100 = 20%.
The 10% and the 20% gives us a 30% error (inaccuracy/your measurement x 100) in the solubility value.
It was difficult to ensure that all the water had evaporated. This would give a solubility reading much greater than the correct value.[AA1]
Using a larger volume of solution would reduce the percentage error. However the suggest realistic improvements to the method evaporation will take longer unless we evaporate to dryness in a heated oven or other similar system.[AA2]
The inquiry could be extended by looking at other ionic salts.
[AA3]

[AA1]you EVALUATE the DESIGN of the experiment, looking for inaccuracies:
  • evaluate method
  • comment on reliability + validity e.g. quantities used

[AA2]suggest realistic improvements to the method
[AA3]Make suggestions for further inquiry.