0.3M solution:-
The potato chip decreased in mass. It was a bit softer than before submersion.
0.6 M solution:-
The potato chip decreased mass. It was very soft and flexible.
Results:
Percentage mass change = [(final mass - initial mass) ÷ initial mass] x100
The percentage change in mass was calculated in this experiment instead of the change in mass alone because not all the chips were the same size at the beginning of the experiment, meaning that some chips would be able to take in more or lose fewer substances through osmosis because they had a greater surface area. In taking the percentage change in mass, we account for the differences in the size and surface area of each chip.
Conclusion:
We can deduce from my results that the potato chip immersed in distilled water increased in mass because the potato cells absorbed water from their surroundings by osmosis as distilled water is a highly hypo-osmotic liquid.
The next potato chip is immersed in a solution of 0.1M of sucrose. And so, as there are some solute molecules in the water, it is a less hypo-osmotic solution. Therefore the potato chip will not become as turgid as the one immersed in distilled water. Somewhere between the concentration of 0.1M and 0.2M of it can be deduced that the solutions will become iso-osmotic, i.e., the concentration of the solution within the cell and outside the cell will be the same and so there will be no change in mass of length of the potato chip.
In this way as the concentration of the solution increases it becomes less and less hypo-osmotic, then it becomes iso-osmotic, and eventually, the solution becomes hyper-osmotic. Thus, the cells of the potato chips immersed in the solutions of concentrations 0.6M and 0.7M lose large amounts of water to their surroundings.
Evaluation:
Despite taking several measures to prevent errors from occurring, a certain number of errors are unavoidable. These are mainly random errors which are caused by mistakes made while handling or reading equipment. These are the main reasons for the error bars on the graph of my data.
Special care was taken to ensure that the experiment was a fair test. All the chips were kept the same size, reducing any differences in absorbency due to surface area. The flexibility of chips was tested after they had been weighed to provide us with qualitative data. To improve this experiment a wider range of concentrated solutions could be used to produce more varied results that would highlight, more clearly and accurately, the concentration of the solution inside potato cells. We could have also measured the width and depth of each chip and could have tried to maintain a consistent surface area: volume ratio for all the chips. We could also have measured any change in length of the chips as an extra set of data to analyse.
Overall, this experiment was quite accurate and successful in investigating the process of osmosis and concluding that the concentration of sucrose inside a potato cell is somewhere between 0.1M and 0.2M.
by
elenchus (student)
