A solution effect the rate of osmosis in potato chips.

Apparatus

These are the items I will need for my experiment: -

• Potato
• Goggles
• Potato Borer
• Lab Coat
• Test tubes
• Test tube Rack
• Distilled water
• Sugar Solutions
• Vernier Callipers
• Weighing Scales
• Thermometer
• Stop watch

Prediction

I predict that if you place a weak potato chip in a strong solution the weak solution will pass out off the potato and into the strong solution making the whole thing neutral – Plasmolysis.  If you reverse the situation and have a strong potato chip in a weak solution the weak solution will go into the potato, thus make the potato gain in weight – turgidity

Linking Prediction with Theory

I am going to first look at osmosis. Osmosis is the passage of water molecules through a partially permeable membrane. If water molecules pass from weak solution to a strong solution with the result making a neutral solution, then the cell becomes turgid. If a weak solution passes out of the cell to a strong solution to again make the solution neutral, then the cell becomes plasmolsed.

Osmosis also occurs in plant cells. Osmosis is the way in which many living things take up water. When osmosis happens in plants the cell membrane acts like partially permeable membrane. The cell sap inside the vacuole is the strong solution. When water passes through by osmosis the concentration of the sap inside the vacuole is now neutral. The diagram shows this.

 Plasmolysis is when plant cells are placed in strong solutions water passes out of the cells by osmosis. As water passes out of the cell, the sap vacuole starts to shrink. These cells are no longer firm. They are limp. We say that these cells are flaccid. As more water starts to leave the cell the cytoplasm starts to peel away form the cell wall. These cells are plasmolysed.

Turgidity is when a plant cells are places in a weak solution. The weak solution enters the cell by osmosis. This happens because the cell sap contains a strong solution. The cell membrane again acts as the partially permeable membrane. The cell begins to swell up as water enters the cell. The water then starts to push against the cell wall and soon the cell contains as much water as it can hold. The strength in the cell wall stop it from bursting. We now say that this cell is turgid.  

Procedure

• Get lab coat and goggles.

• Put them on.
• Collect all the apparatus needed for experiment.

• Set up equipment

• Cut the chips out of the potato using the potato borer
• Measure them using the venier callipers and weigh them
• Record these measurements
• Measure out 30ml of solution.
• In ‘A’ place the distilled water.
• In ‘B’ place the 0.2% sugar solution
• In ‘C’ place the 0.4% sugar solution
• In ‘D’ place the 0.6% sugar solution
• In ‘E’ place the 0.8% sugar solution
• In ‘F’ place the 1% sugar solution
• Place the measured chips in each test tube remembering to mark the tube to tell you which chip is where
• Leave for 30 min
• Take the chip out of the test tube.
• Blot it dry
• Re- measure the chip in weight and length
• Record your results in a table
• Repeat the experiment 3 times.

Safety  

When carrying out this experiment I must:

• Wear a lab coat and goggles at all times.
• Keep my hair tied back
• Have my bag and stool trucked under the table

To make my experiment I must maintain all these safety aspects.

Measurements

In this experiment I must measure: -

• The temperature
• The time
• The amount of solution
• The potato chips weight and length

I must try throughout this project to make my measurements as accurate as possible.

 

Now that I have my averages I am going to plot my graph.

Conclusion

My graph is curve. The results and curve of my graph tell me that as the concentration increases the more water that is released from the potato chip. Also as the concentration decreases the more water that is taken in by the potato chip.

All of this occurs because of turgidity and Plasmolysis. These are the two effects of osmosis. In the lower concentration the potato chips become turgid because inside the potato chip there is a high concentration and the low concentration passes through to neutralise this. So the potato gains weight. (Turgidity) In the higher concentration there is a weak solution in the potato chip so the water moves form the potato into the solution trying to neutralise the solution. So the potato losses weight. (Plasmolysis)

Evaluation

Overall our experiment went well. We collect all of our results in the time allowed and we had no anomalies. I think that our method of collecting the results was good but there were a few faults. When we were taking the results we didn’t check the temperature to make sure they were all the same, our measurements were done using the human eye and may have not been correct. Also when we were re-measuring we needed to make sure that there was no excess liquid present and on some we didn’t adding weight to the chip. Lastly when adding the chip to the solution some may have been added before others giving more time for osmosis to happen in some. To improve our experiment we could use a gradual pipit that measures accurately. Also we cloud have placed our test tubes in a water for the whole experiment keeping them at a steady temperature. We could also take more time at the end to fully dry the potato chip before weighing so that all the excess liquid has been removed. To gain further evidence on this topic I will go on science investigates and compare my results to theirs. Their results will have more accuracy so it will be good to compare my pilot investigation to their wider investigation.