Investigating surface area to volume ratio on the rate of diffusion into gelatine cube

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Michael Daniel  

Investigating surface area to volume ratio on the rate of diffusion into gelatine cube

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I predicted that the smaller the cube or larger the surface area to volume ratio the faster the diffusion rate. I was correct, so I am happy with what I have predicted. Although my prediction was correct, I did not think that there would be a pattern. This is clear in the graph.

However, there is one anomalous result. This anomalous result does not fit in with the pattern, all the plots widen and drop-the anomalous result does not drop that much. The anomalous result is the largest cube [cube f] and is the first plot. If you look at the graph closely at the graph, at the top you would see the anomalous result. The anomalous result is the largest cube, we timed the rate of diffusion for the smaller cubes first. So by the time we timed cube F, the concentration of Hydrochloric acid would be weaker then at the start. This could be the cause as this cube took longer to diffuse. But the results show that if a cube has a small surface area to volume ratio [big volume] it would take long. If this is correct the plot [anomalous result] should be at a higher time. So it could be the concentration of acid, or not. The reason why the concentration of the acid could affect the result is because it is a variable, and needs to be controlled. If the concentration were high, there would be more molecules in a fixed volume. These molecules would collide more making them move faster, giving them a higher energy level therefore making the acid diffuse into the cube at a greater rate.

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There are more reasons/exceptions as to why the result is anomalous. Some of these are variables, which can be controlled. We can control these, but not that accurately. But if we can control these, they should not make much of a difference. However, if combined they could. The concentration of alkaline is another variable that can be controlled. This is because the alkaline adds to the phenolphthalein, giving it a pink color. As we are using the acid to diffuse into the gelatine, the acid has to diffuse also/pas through the alkaline. If the alkaline is at a higher concentration, ...

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