2019 Year 12 IB Extended Essays

G RAPH 1:

Average distance of nth ring from gel surface in cobalt(II) chloride- ammonia Liesgang rings

10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60

2.5 3 3.5 4 4.5 Linear (2.5) Linear (3) Linear (3.5) Linear (4) Linear (4.5)

Distance of ring form gel surface. (mm) ±1 mm

0 2 4 6 8

4

5

6

7

8

9

10

11

12

13

14

Ring number

The graph only starts at the 5 th ring because the distance variation at the upper end of the test tube was too difficult to definitively distinguish. The vertical error bars represent the error associated with the dependent variable. This error is ±1mm and is due to the accuracy of the ruler used to measure the distance of each ring from the gel surface. There is also no horizontal error as there was none associated with the ring number. As the laboratory had highly accurate electronic balances there was very little impact associated with the error of the mass within the experiment. However, the inaccuracy of the ruler is likely to have both a negative and positive impact on the data.

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