Osmosis And The Egg - Lab Report Example

Osmosis And The Egg Purpose The aim of this experiment was to use an egg to test the effects of osmosis and to determine if the size of the egg changed when it was exposed to different solutes. Background Diffusion is the process whereby molecules travel from high to low concentrations producing a uniform mixture. Osmosis is a specific form of this where water molecules travel across a semi permeable membrane in response to the difference in concentrations, also known as the gradient in concentration. This transport is passive and does not require any energy. Water molecules will move in the direction of a high concentration of solute, and hence low water concentration until equilibrium is reached. Generally osmosis occurs across a cell membrane; however, this is not always the case. The outside solution can be grouped into one of three categories, isotonic, hypotonic and hypertonic. Isotonic is where the concentration of water is the same inside and exterior to the cell, and as a consequence water moves in both directions with no next change. A hypotonic solution has a higher concentration of water compared to the internal environment, and as a consequence water moves into the cell. Finally, a hypotonic solution has a lower concentration of water to the internal environment, so water moves out of the cell . Materials Beaker Vinegar Corn syrup Raw eggs in shell Measuring cylinder Plastic wrap Methods 1. The circumference and mass of a raw egg was measured and recorded 2. The raw egg was placed in a beaker and covered with vinegar poured from a graduated measuring cylinder. The exact amount of vinegar used was recorded. 3. The contain was covered and then left undisturbed for a week 4. The egg was removed from the beaker, carefully dried and re-weighed and measured. Changes in its appearance were noted, and the amount of vinegar remaining in the beaker was recorded. 5. The egg was then placed in a clean beaker and covered with corn syrup from a clean measuring cylinder, the amount of which was recorded. 6. After being covered and left undisturbed for another week, the egg was removed, dried, and its mass and circumference recorded. Changes in appearance were noted and the amount of corn syrup that remained in the beaker was measured and recorded. 7. The egg was placed in a clean beaker and covered with water, the amount of which was recorded. Following which the beaker was covered and it was left for a week. 8. After a week, the egg was removed from the beaker, dried, measured and weighed, and details about the appearance were noted. Finally, the amount of water that remained in the beaker was measured and recorded. Data table Measurements Baseline After vinegar After corn syrup After water Circumference (cm) 13 14.5 12.2 15.5 Mass (g) 51.5 71.89 51.6 78.5 Appearance Oval, smooth, soft Long, rubbery, more cracks Smaller, partly indented Bigger, like a rubber immersed in fluid Amount of vinegar (ml) 60.5 43 - - Amount of corn syrup (ml) 77 - 79 - Amount of water (ml) 67 - - 35 Change in liquid (ml) - -17.5 2 -32 Graph Figure 1: Starting circumference (in centimeters) of the egg and circumference following each of the experimental treatments. Figure 2: Starting mass (in grams) of the egg and the mass following each treatment. Questions 1. The circumference of the egg increased by 1.5cm after it was immersed in vinegar and left to stand for a week. The mass changed, increasing by around 20g. Overall, the size of the egg increased. The amount of vinegar in the jar decreased by 17.5ml. The changes were the result of osmosis. The gradient across the membrane of the egg made it such that molecules of vinegar were drawn into the egg, resulting in a lower concentration of vinegar molecules outside the egg and a higher concentration within the egg at the end of the week. The cracks in the shell of the egg were the result of an acidic reaction between the vinegar and the shell of the egg. The rubbery nature was due to the change in chemical composition of the egg, it had more liquid in it as a result of the vinegar. 2. After the egg had been placed in corn syrup the circumference decreased by 2.3cm. The mass changed, decreasing to 51.6g, approximately the same mass as the baseline. The overall size of the egg decreased from its state after the vinegar, returning to roughly the size it was prior to experimental treatment. The amount of corn syrup in the jar increased by 2ml. The egg was lighter and smaller as the differences in water concentration within and exterior to the egg resulted in water being pulled out of the egg. This left it in a more fragile state, meaning it indented easily. 3. When the egg was placed in water the circumference increased by 3.3cm. The mass of the egg changed, increasing to 78.5g. The overall size of the egg also increased, ending up larger than all other treatments. The amount of water surrounding the egg decreased by 32ml. Osmosis is the movement of molecules across a membrane as a consequence of differing concentrations. Water is a molecule that moves very easily through osmosis, and the concentration of this interior and exterior to the egg were substantially different, resulting in the movement of a large amount of water. As a consequence, the egg expanded and became more rubbery due to the increased amount of liquid inside it Limitations This experiment showed the effects of osmosis through the use of different liquids. One problem with the experiment was that only a single egg was used, so the effects of each individual liquid could not clearly be seen. For example, immersing in corn syrup appeared to cause water to leave the cell and can be seen through the decrease in size and mass, however, the amount of liquid only changed by 2ml. Another problem with using a single egg was that any errors in measurement or anomalies will not be noticed as there was no replication. Conclusion The process of submerging the egg in liquid and leaving it for a week allowed the process of osmosis to take place. This is because the egg shell is semi permeable and is able to act in the same way that a cell membrane can in terms of allowing diffusion. Both water and vinegar were hypotonic compared to the interior of the egg and as a consequence immersing the egg in these liquids resulted in water being taken into the egg. This resulted in the egg appearing rubbery and gaining in size. In contrast, corn syrup was hypertonic compared to the interior of the egg so water moved out of the egg. As there was already an increased amount of water inside the egg it was this that was removed, resulting in the egg being similar in size to when the experiment began. References Read More