Apparatus
Potato x 1-this will be our experimenting tissue. It will have to be the same potato and will have to be treated in the same way.
Blotting Paper x 2-I will use this after my experiment. I will take of any excess water of the disc when I am measuring the mass after.
100ml Beaker x 6-A test tube would be too small and there would be a danger of spillage. As we are only using 50cm3 of solution there will this beaker is more suitable
100ml Measuring Cylinders x 2-As both solutions are different (one is distilled water and one is salt solution) I will be using two different cylinders.
White Tile x 1-this white tile is ceramic and will only be used for safety purposes and to stop any damages towards the school property.
Distilled water x 1 bottle-Tap water is not exactly pure so it would affect my results.
1 mol/dm3 Salt Solution x 1 bottle-for all my solutions the same strength will be used.
Cork Boarer x 1-there are two types of cork boarers they differ in the diameter, I will use the thin one and keep using the thin one.
Scalpel x 1-The scalpel is extremely hard and extremely dangerous. It will be used to cut up the potato discs.
Ruler x 1-the ruler will be used to measure 10mm of each potato disc.
Electric Scale x 1-these will be used to measure mass before and after the experiment.
All these apparatus will be obtained from the technician’s room on the same floor.
Safety Points
- For safety precautions my work surface will be cleared from any objects that are not needed such as book, diary pencil case etc. I will remove any barriers. Also I will put my chairs on a side, as I will have to be standing up to check the measurement of solution. Someone else may stumble over the chairs so that’s why I will put them away.
- We are going to be using concentrated salt solution. This may not be that dangerous, but if we get it into our eyes then we will see further implications to this. To prevent this I will be wearing goggle provided by the biology department.
- As we are using glass beakers I need to hold them very carefully. If they do slip or fall out of my hand I will make sure no one goes near it, as it will be a safety hazard to others. I will get a dustpan and brush and quickly clear it up.
- Whilst I am using the scalpel I must not walk around the room with it in my hand. I should always cut upon the white tile to prevent injuring others or myself.
- Electricity conducts any type of liquid, so when I am using the electric scales I must avoid any spillage of the concentrations.
- Any potato left on the work surface should be cleared away immediately from the surface and the floor as it is a slipping hazard
- To stop bacteria from multiplying before and after the experiment wash your hands and wipe the work surface with a damp cloth.
Method
Firstly I will need to prepare 6 different solutions.
- The first solution will be 50cm3 of distilled water. I will measure out 50cm3 in one of the 2 100ml-measuring cylinders. To make sure I have the accurate amount of liquid in the cylinder I will look at it at eye level this will make my results more accurate. When it is measured I will pour it into a 100ml beaker and then I will label the beaker stating which solution it is and how much it has. This will help me when it comes to me finding my results it will make the process more efficient.
-
The second solution will be a 1 mol/dm3 Salt Solution. I will measure this 50cm3 of this out in another 100ml measuring cylinder. Again to make sure the same amount of liquid is poured in I will look at it at eye level. After I have measured it out I will pour it into another 100ml beaker and then label the beaker stating which solution and how much it has.
- The third solution will be 40cm3 of 1 molar salt solution. I will measure this in the previous measuring cylinder used for the salt solution. I will pour in 40cm3 and check it at eye level. Then I will pour it into a third 100ml beaker and label it with the amount and type of solution. I will get distilled water and measure out 10cm3 in the measuring cylinder I used for distilled water and check it at eye level. After I have measured it I will pour it into my beaker, which contains the 40cm3 of salt solution. I will have to label it
- The fourth solution I will be making will be 30cm3 of 1 molar salt solution .I will measure it in the salt measuring cylinder and check it at eye level. Then I will pour it into the fourth beaker. Then I will get the water measuring cylinder and measure out 20cm3 of distilled water I will then check it at eye level. Then I will pour it into the beaker, which contains 40cm3 of salt solution. I will then label it.
- The fifth solution I will be making will be 20cm3 of 1 molar salt solution. I will measure it in the salt measuring cylinder and check it at eye level. Then I will pour it into the fifth 100ml beaker. Then I will measure 30cm3 of distilled water in the water-measuring cylinder. Then I will check it at eye level and pour it into the beaker containing the 20cm3 salt solution. Then I will need to label it
- The sixth and final solution will consist of 10cm3 of 1 molar salt solution. I will measure this in the salt measuring cylinder and check it at eye level. Then I will pour it into the sixth beaker. I will then measure 40cm3 of distilled water in the water-measuring cylinder and check it at eye level. I will then pour this into the beaker along with the 40cm3 salt solution.
- Next I will need to prepare 18 potato discs/chips each of the length 10mm.I will obtain 18 out of 1 potato need 18 as I will be placing three discs in each test tube for more varied and reliable results. I will not wash it or peel it will need the white tile a scalpel a pencil a ruler and a weighing scale.
- I will place the white tile upon my work surface. On the white tile I will place the potato. I will get the thin cork boarer and push it through the potato. Then to get the potato chip out I will use the end of a pencil to get it out.
- The ends of the potato will have the skin on them. I will carefully cut it off by using a scalpel. then I will get a ruler and measure each potato disc at 10mm.i will only do this for maximum accuracy.i will have to do this six times as 3 discs can be obainted from 1 potato stick.
- I will have 6 groups of three potato discs/cylinders. As three will go into each beaker of solution.I am putting three chips in each beaker because my results will be more reliable.
- Then I will eacgh potato disk befor I put it into the beaker.I will place the weight on my table of results. Then I will work out the average of it.
-
I will place three discs in each beaker.I will leave them there in my 4th period and come and check the after weights the next morning.
- The final bit of my experiment will be to record the weight after osmosis has takien place.
- I will take out the three potatoe chips and dry them on blotting paper.I will then weigh them and record my results. I will do this 6 times for each beaker.Then I will calculate the average after and change in averages.
- I will be able to know if osmosis has taken place if when plotting my graph I see an s shape.
Observation
Raw Data
I would collect this data manually and there will be no need for me to use any calculator
Calculated Results
I calculated these results as I used a calculator to find out the average. This was done as I added the 3 masses and divided them by 3
Analysis
Analysing my graph it shows me the higher the concentration of my created solution the more mass the potato chip lost. Yet the lower the concentration of my created solution the more mass it gained. My line of best fit is approximately like my predicted one. Which shows that my experiment is accurate and reliable. The more concentrated the solution was the more mass the potato chip lost. The more dilute the solution was the more mass it gained. The pattern of my graph was going quite normally until I reached the 100% concentrated solution. Here I could see a visible anomaly that caused my graph to shape out of its trend. On my predicted graph the trend was a flat region at the top an inward curve and a flat region at the bottom. The predictive graph is very similar to my graph that is supporting my data. My line of best fit shows that as the concentrated solution increases the mass of the potato decreases. I can see this, as it is a negative line of best fit. I don’t think my anomaly should be taken into consideration as it is minor and does not differ very much. During osmosis I noticed that my potato chips expanded. In the 0 dm3 solution after I calculated the change in average was +0.43.The only reason the potato chip increased mass was because osmosis took place in the potatoes vacuole. This is because it was a plant cell not an animal cell. As the concentration of the created solution was 0.8 dm3 the change in average was –0.4.the surface area became smaller. And the vacuole lost its weight.
The appearances of the potato chips were very interesting. You could tell straight away whether a potato had lost weight due to it looking shrivelled. You could also tell straight away if the potato chip gained mass due to its expanded surface area and increased thickness.
Conclusion
Overall I think my experiment was very successful. The first prediction I made at the beginning of the investigation has also been effectively proved and supported by my data, by my results. I predicted that the high concentrated solution would cause the potato chip to lose more weight whilst the low concentrated solution would cause the potato to gain weight. I also predicted why this effect would take place. It would be due to the osmosis process-taking place in the plant cells vacuole. When the vacuole has osmosis-taking place it will expand and if solution is a high concentration then the vacuole will lose its solution and become shrivelled.
Osmosis is the science theory of water molecules moving from a high concentration to a low concentration. When I created my high concentrated solutions and placed the potato chips into them they lost weight. This is due to the water molecules from the solution trying to move to a low concentrated area i.e. the potato chip. When I created my low concentrated solutions and placed the potato chips into them they expanded and gained weight. This is due to the water molecules in the solution of a low concentration therefore as the process states the y would move to a highly concentrated area. This is why the potato gained weight.
All the above is what I experienced and predicted. So therefore I think my results are reliable and precise as the support, justify and prove my given prediction.
Evaluation
My experiment result as there was no radical changes in the masses of the chips. I had one anomalous result from my data. Even though my results were accurate and I controlled all variables I still managed to get an anomalous result.
Taken as a whole I was really dependant on my method. If I didn’t have my method I know for a fact that I would not be able to do the experiment. As I did have a detailed method to help me can prove it had no problems and it is a good method because my results and graph was accurate.
I think this result occurred due to me trying to get excess water of the potato by using blotting paper. You can’t really measure if you have got all the excess water off and you are using the paper equally. This anomalous result could have been prevented if I didn’t use blotting paper at all but this would have still had some side effects towards my results.
Another area, which I could of, improved would have been the time period as I only left my chips in the solutions for 12 hours. I didn’t really know that osmosis had fully taken place. However if I had left them for 24 hours then I would be assured that osmosis had fully taken place and my results would be precise and consistent.
The last thing I would improve would be to develop the variety of concentrations I used for this experiment. If I had 12-14 created solutions instead of 10 then my results would have been accurate. From this I would receive better and more results for my graph and my line of best fit would be correct and accurate.
Instead of a potato tissue I could of used an onion cell or a fruit cell such as an orange. Then After I completed both experiments and shaped graphs for them I could evaluate them and I could see if the process was similar or diverse.
I think my results drawn were reliable. There were a good variety of results taken. But they didn’t vary drastically. This shows me that my results were accurate. Also as I received an anomalous result I think that tells me that my results were accurate
In general I think my experiment went quite well and was planned correctly by myself. The results I produced from this experiment were accurate as they backed up and justified my prediction.
Diagram