What is the osmotic pressure of the average potato?

The hollow metal cylinder was used to punch out ten potato cylinders out of the potato. The glass rod was used to push the potato out of the cylinder. These potatoes were then cut in half, and had the ends carrying skin taken off as well. These potatoes were then weighed on the scale, and trimmed until they all were a relative same size, the average would be found later. The ten beakers were then filled with 100 ml of distilled water, and five of them were marked with 0%, .5%, 1% 2% and 3%. The other five were also marked the same way but with a different color.

The next step was to make the concentration. A paper towel was placed on the scale, and on the scale we weighed .5g, 1g, 2g and 3 g of sodium chloride (each one twice). Then the .5g of sodium chloride was placed in the beaker marked with .5%, and so on for each of the different weights of sodium chloride. The beaker marked with 0% was kept distilled. The glass rod was then used to distill the sodium chloride faster by stirring the water. When the sodium chloride was not seen anymore the cylindrical potato samples were placed in the beakers and left there overnight. The next day they were taken out, and weighed, then the percent difference of each from day 1 to day 2 was calculated.

DATA 1

Concentration of NaCl

Original weight of potato (g)

Weight after left overnight (g)

Difference in weight (g)

Percentage difference

0%

2.99

3.16

0.17

6

.5%

2.99

3.04

-0.05

2%

%

2.99

2.85

-0.14

-6%

2%

2.99

2.18

-0.81

-27%

3%

2.99

.87

-1.12

- 37%

DATA2

Concentration of NaCl

Original weight of potato (g)

Weight after left overnight (g)

Difference in weight (g)

Percentage difference

0%

2.99

3.35

.36

2%

.5%

2.99

3.08

-.09

-3%

%

2.99

2.98

-.01

-0%

2%

2.99

2.17

-0.82

-27%

3%

2.99

.83

-1.16

-39%

AVERAGE DATA

Concentration of NaCl

Average percentage difference

0

9%

.5%

2.5%

%

-3%

2%

-27%

3%

-38%

Most variables were controlled, such as sodium chloride. The only two I can think of are the age of the potato and the temperature that might have had affected the rate of osmosis. The age wasn't an issue as the potatoes all seemed fresh and of the same age, and temperature stayed the same as the potatoes were inside a room, and thus maintained at room temperature.

Thus we see that the osmotic concentration is of .7%. for future reference the best thing to do is to completely dissolve the sodium chloride in the water, as we didn't do so this time. To go further with the experiment testing other foods would be a good idea, such as apples, or macaroni.