Plan
In this experiment I plan to investigate how different factors of sugar solution affect osmosis in a potato. By witnessing these effects taking part during the practical, I will record different aspects that will obviously need investigating. I will record the weight at the start of the experiment and the weight after. Then I will record change in weight and the percentage change for each chip at the different concentrations. From each concentration consisting of 3chips, I will then calculate an average, which would take part when plotting my graph. I will also do a preliminary test and record the results as a back up plan.
Prediction
I predict that as the concentration of sugar solution increases, the weight of the chips will also increase. If the chip is put into a higher concentrated solution, the water molecules are transferred into the chip, which makes the cell turgid. This is a result of the movement of concentrated solution.
By referring to the diagram above, as you can see if the concentration of water is low, the sugar solutions would be more outside the cells, whereas if the water concentration is high the sugar solution would be low inside the cells. The mass from the high water concentration would be less (direction of the arrows) whereas once the water is low concentration then the mass of the chip would be high (reverse of direction arrows).
Preliminary work
Before going into great detail and investigating the key factors, I planned to do a preliminary test. The molar solutions were not exactly the same as the real practical, but were jus brief. I used the solution of 0M and 1M, and just in between I used 0.6M. Below shows the results after my preliminary work.
Weight/mass before weight/mass after
From my results obtained from the preliminary tests, I discovered that the results were significant and made sense.
Fair Testing
Throughout the whole practical, fair testing would play an important part. Without having fair testing, then all the results we have gathered would be false, eventually our conclusion wouldn’t make sense.
The potatoes would need to be cut accurately and be the same length. The chips would also be cut from the same variety of potatoes. By doing this, we may need to measure the chips with a ruler, and cut parts off the chips if necessary. Even when weighing the chips, the readings need to be accurate and familiar. By doing this we will read the scale to the nearest 2 decimals. I would also need to make sure; nothing disturbs the scale (sensitive balance). By doing this I will make sure, that extra weight or paper is not affecting the scale. I will also make sure, the scale reads zero, before weighing anything
Also another factor that may affect the practical is the temperature. We musts make sure the temperature is constant, and doesn’t differ. For example doing the first half of the practical sunny, and the second half windy, will result in our practical with false readings.
We must also make sure that the making of solutions is done accordingly to the table given. If the solution in one test tube is different than the other this will affect the results resulting in an awkward pattern. Leaving the dish and chips out for 24 hours would be affected if tampered with, so it needs to be kept in a safe place, away from any tampering, which would affect the whole practical.
Also once the measuring cylinder has been used, we will need to make sure it is washed out properly to ensure that unauthorized solutions are kept inside the tube, which can also affect the experiment. With the different concentrations OM, 0.2M, 0.4M, 0.6m0.8M and 1M I will still use the same method no matter what.
Method
During the practical, a group of 4 people had to take certain roles, for the investigation to go smoothly. Firstly one person had to cut out 18 potato chips from a potato using a cork borer, from a diameter, about 6mm in a cylinder shape. A second person was required to cut the chips into the same length, with a knife, which was about 6cm long. We then decided to put 3 of each chip into each concentration of sugar solution. The third person then had to be able to make the solutions correct and as accurate as he can. By doing this, he had to follow a precise table below:
After the making of the solutions was completed the fourth person had to weigh the chips. We weighed 6 sets of 3 potato chips. The reason why we weighed 6 sets was because we have to tests the potatoes in 6 different solutions, 1, 0.8, 0.6, 0.4, 0.2, and 0 molar solutions to make things even. We weighed the chips before and after the practical and recorded the results. We then followed a general formula, and applied that towards our results. This was our percentage change in mass.
Change in mass (g) * 100
Mass at start (g)
Apparatus
Measuring cylinder
Petri dish
Tweezers
Cork borer
Ruler
Labels
White tile
Safety
Safety would play a huge part in this experiment. The different aspects of safety apply to everyone in the group, and must be followed, or else it can lead to dangerous precautions. The potato borer and knife both should be handled securely and shouldn’t be treated as toys.
The whereabouts of glass from the cylinder should be placed in the centre of the tables, since people would accidentally bump into the table. If glass is broken, it should be placed in the “glass bin” only. Also walking around the class with glass in your hand needs to be carefully done, or people may bump into each other. Apart from that, the experiment will be fine.
Table of Results
Below is a table showing how the results went during the experiment. My table shows the weight/g of chips before and after, with the 6 concentrations of sugar solution. I will also include the change in weight/g and the percentage change, which follows the formula of:
Change in mass (g) * 100
Mass at start (g)
I also included another table below to show the average percentage change, which would play a part when drawing up my graph.
Conclusion
By looking at my graph which shows the average percentage of change in weight
