2019 Year 12 IB Extended Essays

EVALUATION

Error

Effect/Impact

Improvement

The use of a 30cm ruler created random error in the experiment. The ruler though easy to use was highly inaccurate. With only a smallest measurement of 1mm it was hard to distinguish exact distances. The ruler was also hard to use when measuring against the test tube. Having to hold the ruler against the test-tube and use eyes to find the measurement resulted in errors created by parallax as well as random error associated with holding the test tube and ruler parallel. This method was likely to have a large impact. Random error was introduced through the transfer of mass from the measuring cup to the beaker. Even though the scales themselves had a very high accuracy of ±0.0001 grams. It was noticed that there was still residue within the measuring cup causing random error. The large difference between the test trials and experimental trials could have been due to the temperature change. Temperature potentially introduced a systematic error into the experiment.

As already shown the use of a ruler will have an create an uncertainty of ±1mm

The use of a calliper would have resulted in more accurate distance measurements. Not only would a calliper be able to be more accurate than 1mm it would also reduce the effects of human error and parallax.

The random error created would likely

To make sure all of the mass is used in the experiment a brush could be used to sweep the residue. One could also use a small amount of deionised water to absorbs any residue. And then pouring the water in the beaker The test-tubes could be placed in a water bath kept at a constant temperature during the time of formation. Keeping the test-tubes at a constant temperature would eliminate the potential for error due to temperature changes. A water bath could also be used to find an ideal temperature for formation conditions.

contribute to an error of ±0.01 g

Temperature as a systematic error was unlikely to impact the trend between variables but more likely to impact the value of each measurement.

As seen in the results change of mass has little effect on ring formation, therefore an extension which looked at formation conditions would be beneficial. Testing the direct effect of temperature on formation could be one option for an extension. Other extension opportunities would be to see the impact of different compounds, instead of vertical rings in test-tubes conducting the experiment in petri dishes could also be possible.

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