Osmosis Lab Response
9/17/2013, Lois Andersen & Claire Ma
“The Power of Osmosis” The purpose of the lab was to discover, through osmosis, the concentration of sugar water in a potato. First, potatoes were cut into strips about 3 centimetres in length and six strips were individually massed. Next, the six strips were placed in 6 different Dixie cups, labelled A, B, Q, X, Y, and Z. Each of the Dixie cups were then filled just enough to cover the potato strips, with substances that matched the letters of the cups. About 24 hours later, the potatoes were taken out of the Dixie cups and were individually massed again. The resulting data is as follows.
Change in Mass Over 24 Hours
Variable
A
B
Q
X
Y
Z
Original Mass
1.93 grams
2.04 grams
2.20 grams
2.27 grams
2.73 grams
2.58 grams
“After” Mass
1.55 grams
1.51 grams
2.35 grams
2.90 grams
1.88 grams
2.41 grams
% Change
-20 %
-26%
+7%
+28%
-31%
-7%
Percent Change in Concentration
Variable
Concentration
X
0
Q
0.2
Z
0.4
A
0.6
B
0.8
Y
1.0
As the concentration of a solute in water will, through osmosis, transfer until the concentration is nearly the same both inside the cell, or in this case potato, and outside of the cell, the potato strips both gained and lost mass due to the different concentrations of sugar in water. As expected, the potato strips placed in the concentration of sugar water closest to the concentration of sugar water in a potato had the least amount of change in mass. As the potato strips placed in substance Z and substance A both changed 7%, the concentration of sugar water in a potato must be somewhere in between a concentration of 0.4 and 0.6. One source of error for this lab is that the amount of substance placed into each Dixie cup was not measured and therefore were not consistent. If this lab were repeated, it is suggested that the amount of substance be measured in order to produce more consistent results.
“The Power of Osmosis” The purpose of the lab was to discover, through osmosis, the concentration of sugar water in a potato. First, potatoes were cut into strips about 3 centimetres in length and six strips were individually massed. Next, the six strips were placed in 6 different Dixie cups, labelled A, B, Q, X, Y, and Z. Each of the Dixie cups were then filled just enough to cover the potato strips, with substances that matched the letters of the cups. About 24 hours later, the potatoes were taken out of the Dixie cups and were individually massed again. The resulting data is as follows.
Change in Mass Over 24 Hours
Variable
A
B
Q
X
Y
Z
Original Mass
1.93 grams
2.04 grams
2.20 grams
2.27 grams
2.73 grams
2.58 grams
“After” Mass
1.55 grams
1.51 grams
2.35 grams
2.90 grams
1.88 grams
2.41 grams
% Change
-20 %
-26%
+7%
+28%
-31%
-7%
Percent Change in Concentration
Variable
Concentration
X
0
Q
0.2
Z
0.4
A
0.6
B
0.8
Y
1.0
As the concentration of a solute in water will, through osmosis, transfer until the concentration is nearly the same both inside the cell, or in this case potato, and outside of the cell, the potato strips both gained and lost mass due to the different concentrations of sugar in water. As expected, the potato strips placed in the concentration of sugar water closest to the concentration of sugar water in a potato had the least amount of change in mass. As the potato strips placed in substance Z and substance A both changed 7%, the concentration of sugar water in a potato must be somewhere in between a concentration of 0.4 and 0.6. One source of error for this lab is that the amount of substance placed into each Dixie cup was not measured and therefore were not consistent. If this lab were repeated, it is suggested that the amount of substance be measured in order to produce more consistent results.