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jamiewatson1987
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#1
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HELP!!!

I need help with my Osmosis investigation!!!
My Osmosis is where we put them in sugar soloutions for a set time and then remeasure them to see if they hav changed in size!

PLEASE PLEASE PLEASE HELP THIS INVESTIGATION MUST BE IN WEDNESDAY THIS MONTH!

THANKS,

JAMIE
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Dickie
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(Original post by jamiewatson1987)
HELP!!!

I need help with my Osmosis investigation!!!
My Osmosis is where we put them in sugar soloutions for a set time and then remeasure them to see if they hav changed in size!

PLEASE PLEASE PLEASE HELP THIS INVESTIGATION MUST BE IN WEDNESDAY THIS MONTH!

THANKS,

JAMIE
put what in sugar solutions? and you didnt say which aspect you need help with
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CHAD
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(Original post by jamiewatson1987)
HELP!!!

I need help with my Osmosis investigation!!!
My Osmosis is where we put them in sugar soloutions for a set time and then remeasure them to see if they hav changed in size!

PLEASE PLEASE PLEASE HELP THIS INVESTIGATION MUST BE IN WEDNESDAY THIS MONTH!

THANKS,

JAMIE

It shouldnt have changed in size because osmosis is the net movement of WATER molecules through a semi permeable membrane from a dilute solution to a concentrated solution. The semi permeable membrane has holes which are to small for glucose and other sugars to pass through but big enuf for water molecules, therefore, the sugar solution cant get inside and they therefore cannot increase in size, but i dont no weather they can decrease or not.
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Dickie
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(Original post by CHAD)
It shouldnt have changed in size because osmosis is the net movement of WATER molecules through a semi permeable membrane from a dilute solution to a concentrated solution. The semi permeable membrane has holes which are to small for glucose and other sugars to pass through but big enuf for water molecules, therefore, the sugar solution cant get inside and they therefore cannot increase in size, but i dont no weather they can decrease or not.
!?!?! the water will have moved from both sides to balance the concentrations. so it will increase or decrease in mass depending on the concentration outside the thing
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CHAD
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(Original post by Dickie)
!?!?! the water will have moved from both sides to balance the concentrations. so it will increase or decrease in mass depending on the concentration outside the thing
it is a sugar solution the thing is in so the sugar cannot go into the thing therefore wotever it is cannot increase in size, but as I said, I dont no weather it can decrease or not.
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CHAD
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(Original post by CHAD)
it is a sugar solution the thing is in so the sugar cannot go into the thing therefore wotever it is cannot increase in size, but as I said, I dont no weather it can decrease or not.
but it probably will decrease actually
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thefish_uk
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(Original post by CHAD)
it is a sugar solution the thing is in so the sugar cannot go into the thing therefore wotever it is cannot increase in size, but as I said, I dont no weather it can decrease or not.
But what is the thing!?
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CHAD
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(Original post by thefish_uk)
But what is the thing!?

I dunno
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sam1111_9
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i had 2 do the same osmosis investigation last term, and i managed to get full marks - 8886.

I have included my coursework for u!

cudn't save last bit as an attachment tho, so i have copied my conclusion and evaluation below:

conclusion

Conclusion

From the results above, I have found that the results all follow a pattern; as the concentration of sucrose solution increases, the mass of the potato plugs decreasing. Where as, the plugs in the lower concentrations, increase in mass.

This is because, in high concentration sucrose solution, there is a great deal of sugar molecules, and fewer water molecules. This therefore means that the relative concentration of water molecules inside the potato plug is much higher than that outside the potato plug. Due to osmosis, these water molecules diffuse through the partially permeable membrane, out of the potato plug (where they are in high concentration), into the sucrose solution, (where they are in low concentration). It is unavoidable therefore, that due to this loss in water molecules, the mass of the potato plug decreases.

When there was almost an equal balance of water molecules inside and outside the potato plug, osmosis still took place, but the process of osmosis finishes when the relative concentration gradient of water molecules is even on both sides of the partially permeable membrane, hence, only a few water molecules diffused. This therefore means that the change in mass would be negligible. (For example, 0.2M sucrose solution.)

Again, following the same pattern, when there is a greater concentration of water molecules outside the plug, than inside the plug, osmosis causes water molecules to diffuse into the plug. This means that the mass of the potato plug would increase, (such as in the case of 0M sucrose solution.)

My conclusion also supports my prediction that mass would decrease, as the sucrose concentration increased.

Evaluation

In general, I feel that the procedure that I used worked out well, and I feel that the evidence that I collected was fair and reliable.

I think that the evidence that I have collected is good quality. My only major concern was my first attempt at the experiment; the mass of the potato plug increased, even though it was put in 1M sucrose solution, and I would expect the mass to dramatically decrease. However, I decided that this was because I made an error in the procedure of my test, by putting all three plugs in one cup. I changed my method, and put one plug in each cup. This in turn made the results change to how I expected them to be, the plugs decreased in mass. Apart from this, I feel that my other results are fairly accurate, as the measurements for all three attempts are close together, and they all follow the pattern that I would expect.

The method that I used after making the above change was very suitable, as it gave me accurate results.
However, if I were to carry out the experiment again, then there would be some changes that I would make:
Firstly, the results would be more reliable if all of the tests were carried out on the same day. This is because the temperature would remain constant. This would make the results reliable because the temperature can speed up and slow down osmosis.
Likewise, it would be beneficial to use the same potato, although this may not be possible due to the large amount of potato plugs needed for the experiment. In which case, it would also improve the experiment if the same variety of potato were used. As the type, and age of the potato can also affect the rate of osmosis. Although when I carried out the experiment, I tried to use the same variety of potato, it was not possible, and so I used two different types: ‘Saxon’ and ‘Nadine’ – both of which however are baking potatoes, but there is still, room for improvement.
The final thing which I would change, would be the way in which I made up the different concentrations of sucrose solution; I feel I would get more accurate measurements if I used a burette, instead of simply a measuring cylinder.

I believe that my evidence is reliable enough to make a conclusion, mainly because I tested three separate plugs, for each different solution. This therefore made it possible to spot any results that I felt were incorrect, and then to re-test the anomalous results. The main example of this which I can give is that mentioned above, the three plugs which were all in one cup, however, I re-tested this concentration and got a whole new set of results which fit in with the pattern I have established.

Finally, I feel that it would be possible to provide additional evidence to support my original prediction, by testing the potato plugs using a wider range of concentrations of sucrose solution, either at closer intervals, such as every 0.1M, instead of 0.2M. Or I could also test a wider range of concentrations, such as 2M sucrose solution.
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Dickie
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#10
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(Original post by CHAD)
I dunno
how can we help you if you dont know what you're doing?!
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