# Osmosis as a Special Form of Diffusion – Lab Report Example

Osmosis: Permeability Introduction Osmosis, as a special form of diffusion, is the movement of water molecules from a high concentration area to a lower concentration area. The extent of solute concentration in solvent is referred to as tonicity. When a sucrose solution contains more water and less sugar than the egg, the solution is hypotonic and will result in movement of water from the solution to the egg, increasing the egg weight. On the other hand, when the egg solution has less water, that is, it is more sugar concentrated; the solution will draw water from the egg causing weight loss. This solution is hypertonic.
When the level of water in both egg and solution are the same, there will be no change in the egg weight, a situation in which the solutions are said to be isotonic. Conversely, it can be said that the egg is hypotonic when it losses weight, hypertonic when it gains weight and isotonic to in relation to the sucrose solution when its weight is not affected. Three de-shelled eggs were soaked in water, 10%, 20%, 30%, 40% tonicity sucrose solutions and in an unknown tonicity solution and the weight changes observed.
Hypotheses
1. HO – The egg will gain positive weight after soaking in water for 60 minutes.
2. HA – The egg will show no effect after soaking in water for 60 minutes (HO) respectively
Results
Observations made by the various lab groups were tabulated and analysed in tables and graphs as illustrated below;
Table 5.1 – Weight of Eggs (Grams)
Time
Egg A
Egg B
Egg C
Average Weight
Average Percent Weight Change
0
90.1
87.2
87.4
88.5
0
10
94.5
89.4
91.2
91.7
3.62
20
95.3
91.8
92.6
93.2
5.35
30
96.3
92.4
92.7
93.6
5.76
40
98
93.2
93.7
94.8
7.08
50
100.6
95.4
94.3
96.7
9.34
60
99.8
95.1
94.9
96.6
9.15
Table 5.2 – Class Data for Average Percent Weight Change of Eggs in All Solutions
SUCROSE SOLUTION
Time
Water
10% suc.
20% suc.
30% suc.
40% suc.
Unknown
0
0%
0%
0%
0%
0%
0%
10
3.62%
1.02%
0.80%
5.70%
1.65%
-0.80%
20
5.35%
1.01%
0.90%
5.40%
0.44%
-0.80%
30
5.76%
1.00%
1.00%
1.10%
-1.98%
-4.70%
40
7.08%
1.10%
1.10%
0.40%
-1.43%
-11.00%
50
9.34%
1.00%
0.90%
0.20%
-1.65%
-14.00%
60
9.15%
1.00%
2.00%
1.10%
-2.31%
Graphs
Graph 1 – Egg Weight Change in All Solutions (Table 5.2)
Graph 2 – Average Egg Weight Change against Solution Concentration
Discussion
Graph 1 show that water increased the egg weight drastically, while increasing concentration of the sucrose solution resulted in gradual decrease in weight change. The unknown solution decreased the weight of the egg. Graph 2’s trend line basically implies that the egg weight decreases with increase in concentration of the sucrose solution. In this graph, as tonicity increases, egg weight decreases.
Conclusion
The hypotheses postulated that the egg will gain positive weight after soaking in water for 60 minutes (HA) and will show no effect after soaking in water for 60 minutes (HO) respectively. The second postulate is not acceptable as the hypertonic solution does increase the weight of the egg as water moves across the membrane into the egg. The 0% to 30% (graph 2) tonicity sucrose solutions are hypertonic while the unknown solution is hypotonic as it draws away water from the egg, causing a loss of weight. From a reading of the trend line, the exact concentration of the unknown solution is 50%, as the line of best fit shows the rate of decrease in weight as the tonicity of the solution increases. At around 40% tonicity, the sucrose solution and the egg will be in an isotonic state since there is no change in the eggs weight at that point.
Works Cited
Elder, Ken. "Determination of the Isotonic Point of the Contents of a Chicken Egg." Example. Web. 3 Mar. 2015. .