- Then place chip “B” into the second specimen bottle and pour in 60% (6ml) of sugar solution and 40% (4ml) of distilled water.
- In the third specimen bottle, place chip “C” in and add 40% of sugar solution and 60% of distilled water.
- Place chip “D” in the fourth specimen bottle and add 20% of sugar solution and 80% of distilled water.
- In the last specimen bottle place chip “E” in and just add 100% of distilled water. (Step 4,5,6,7 and 8 are all shown in the diagram below)
- Next, leave all the specimen bottles over night and obtain the results the following day.
- Take all five-specimen bottles and pour all the liquids out (sugar solution and distilled water). Then measure the weight and height of all the chips again. Record all the results in table form.
- Dispose of the potato chips.
Results
The First Results.
Results After Experiments
Conclusion
Having completed the experiment and collected the results, I can know say that my prediction was true. As we increased the concentration of sugar solution, the weight and the height of the potato chip decreased.
At 0% sugar solution i.e. 100% pure water, there was more water molecules outside the chip then inside. Therefore water moved from a high concentration (outside the chip) to a low concentration (inside chip). This resulted in the chip weighing more, an increase of 0.2 grams. The height of the chip also increased from 4cm to 4.3 cm, an overall 0.3 cm increase. This made the appearance of the chip look fatter.
At 20% sugar solution i.e. 80% water, there was still more water outside than inside thus water moved into the chip. There was an increase in weight and height, however it was not as much as 0% sugar solution. The height increased by 0.1 cm and the weight by 0.1 grams.
At 40% sugar solution i.e. 60% water, an interesting result occurred. No net movement of water molecules was observed. For this to happen there must have been the same concentration of sugar inside the potato and outside the potato. The weight of the chip stayed the same but the height slightly changed by a decrease of 0.05 cm. The slight decrease in height could have occurred due to in accurate reading of the ruler, as I did expect the height to stay the same.
At 60% sugar solution i.e 40% water the weight and height decreased. Water particles moved from inside the chip to outside. There is a greater difference observed due to the increased concentration of sugar. Weight loss of 0.3 grams and a height loss of 0.4cm.
Finally, at 80% sugar solution i.e 20% water, the weight and height decreased a considerably amount. The weight decreased by 0.4 grams and the height by half a cm. There was a higher concentration of water molecules inside the chip and thus due to osmosis the water moved out of the chip into the region of low concentration.
From analysing the results, I noticed that 40% sugar solution was acting as a central point, dividing the increase and decrease of the weight and height of chip. Below 40% sugar solution there was an increase in weight and height and above 40% sugar solution there was a decrease in weight and height.
Evaluation
The method for the experiment could have been improved in many ways. One could have used a more accurate scale to measure the weight of the potato chips. Also before pouring the sugar solutions into the specimen bottles, one should always remember to stir the solution with a glass rod so that the sugar molecules are evenly distributed and are not just sitting at the bottom of beaker. It is also important to use distilled water and not tap water as it contains impurities and minerals and these impurities could have an effect on the experiment.
Its important that a fair test is always conducted as this allows one to achieve more accurate and reliable results. I tried to make it a fair test by using the same potato for all my samples and made sure all the potato chips were roughly cut the same size and weighed the same. I believe my results were quite reliable and there weren’t many anomalies.
Further work could have been done to achieve a wider range of results such as measuring the results at say 25%, 30%. 35%, 40%, 45% etc. By doing this we would have achieved more accurate results which might have defined a clearer pattern. This would have given more evidence for our conclusion and would have extended our investigation.
I enjoyed doing this investigation, and now fully understand osmosis.
By Zahid Siddique 10E.