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iansmith

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What do you think the osmolarity is based on these observation?

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Hi, after doing a diffusion/osmosis lab, I am being asked to determine the osmolarity of a the potato cores. We recorded the cores' initial mass, placed them in sucrose solutions of varying molarities, and then weighed them one day later. Here are my results:

Sucrose Solution Initial Mass (g) Final Mass (g)

1M 3.071 2.202

.8M 2.953 2.162

.6M 2.894 2.271

.4M 2.862 2.511

.2M 3.112 3.201

Distilled Water 3.021 3.783

I determined the molarity of each solution myself and calculated the percent differences, but I don't know how to "determine the osmolarity of the potato cores". My teacher said that it is up to us to figure out how to do this. I've looked up osmolarity on the internet, but all I see are equations about specific number of particles, etc. I have no idea how to do this with a potato. Please help me out! Thanks!

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iansmith

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iansmith

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Look for osmole value for animal and plant cells.

Check this page

http://faculty.washington.edu/kepeter/119/labs/cell-lab-2005.pdf [Broken]

Check this page

http://faculty.washington.edu/kepeter/119/labs/cell-lab-2005.pdf [Broken]

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Because this is a potential AP question, it almost seems to me that this is a question that I shouldn't need a specific numbers that will not be given to me, as no formulas are given here: http://www.collegeboard.com/prod_downloads/ap/students/biology/ap05_frq_biology_b.pdf

I appreciate all of the help that I've been given thus far, but I'm still not making the connections that I need to.

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iansmith

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First, calculate the osmole value of your glucose solutions.

Second, you have to graph the data (osmole on x-axis and % change in mass on the y axis).

Third, make a best fit curve and find the slope.

Forth, solve for x when y=0.

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