Last updated: August 22, 2019
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EGG DIFFUSION Vs. SALINE WATERAlexandria Brontë – Tinkew17.01.201810TH GRADE SCIENCE (Biology)INTRODUCTIONWhat actually is osmosis? Osmosis happens when a solvent, such as a distilled water passes through a semipermeable membrane into a solution that has a higher concentration of some solute such as salt water. This process can be demonstrated by gummy bears, eggs, as well as potatoes but, eggs are a very good way to demonstrate osmosis because of the thin membrane that lies underneath the shell is permeable to water (which means the water can get in and out if it wanted to). Another way to put this is that:  Osmosis is the movement of a solvent, such as water, through a membrane into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane.As I said before, under the hard outer shell of an egg is a semipermeable membrane. What you don’t know is what it is actually used for? This membrane allows air and moisture to pass through. These are what we call palisade columns. They are naturally narrow pores that all molecules to pass through the eggshell and also allow gaseous exchange. This semipermeable egg membrane allows us to explore of the concepts of diffusion and osmosis in general because water molecules can move into and out of the egg, but larger molecules cannot.What is Supposed to HappenInside the egg, there is a membrane with a solution of proteins and water. When the egg is soaked in water, the water is supposed to be diffused into the egg to equalize the concentration of water on both sides of the membrane, and the egg increases in volume. If another egg is soaked in concentrated salt water, osmosis causes again the water alone to diffuse into the egg, and the egg is supposed to be increased in volume. AIM OF LABWe all know what happens when a egg without shell enters into a glass of distilled water, but what happens to it when salt is added to it?The goal of the experiment is to demonstrate the process of osmosis by measuring the change in volume of the egg and then relate this to how water moves in and out of living cells.HYPOTHESISHypothesis 1: If I put the egg in vinegar then, the egg shell would dissolve from off the egg and become bouncy because of how the chemicals in vinegar would react to the shell.Hypothesis 2: I believe that if we put different amounts of salt in each beaker, then in each beaker with more salt the eggs will have less mass at the end than the beakers with less salt because the salt mixed in would slow the process of osmosis since the salt water outside the egg has a higher concentration than the water inside the egg which means that the water will leave the egg to bond with it.MATERIALS5 Beakers175 mL of Water (each of the beakers)Container of Salt5 EggsA Teaspoon5 Small BeakersScale5 Weighing BoatsVARIABLESIndependent: Amount of Salt in WaterDependent:Mass of Eggs, Salinity of WaterControlled:Time175 ml of WaterSmall Beakers on top of eggs filled with 40 mL of waterVinegarAmount of EggsPROCEDUREDay 1Gather 5 eggs and weigh them separatelyRecord your resultsWrite names on the beakers and label them A, B, C, D, EPlace each in a beaker and cover with vinegar To keep down the egg, place a smaller beaker filled with water on top of each of the eggs (to weigh it down)Leave for 24 hoursDay 2Rinse egg and try to remove as much of the shell as possible. Dry the egg reweigh on a weighing boatRecord resultsPlace all eggs in 175 mL of distilled waterPut 1 tsp of salt in Beaker APut 2 tsp of salt in Beaker BPut 3 tsp of salt in Beaker CPut 4 tsp of salt in Beaker DPut 5 tsp of salt in Beaker EDay 3Remove eggs from solutionsRinse and reweigh again on the weighing boatRecord resultsOBSERVATIONS/ RESULTS and OUR DATAIn Vinegar: At first, when we put the eggs in the vinegar, it was cold from being in the fridge. We noticed that because of this, the eggs wasn’t bubbling and dissolving until a few mins after. This is because the molecules in the vinegar would be moving slow since it was cold and have less energy than if  it was to be in warm and hot water. We checked back on the eggs after putting them in the vinegar solution. My hypothesis was correct though. All of the eggs, lost their outer shell membrane and they also increased in size because the water that was in the vinegar moved into the egg making increase in size. In Salt:We placed the eggs into their solutions at different concentration levels of salt. An observation we made is that the higher the concentration of salt in the eggs, they began to float and we had to put our tiny beakers on top to keep them below the line we marked. We put 40 mL of water in each of the tiny beakers to hold it down.So after a day, we took out the eggs from the salt water. My hypothesis was correct as well, the eggs increased, but were all at different masses. OUR DATAEGGSINITIAL MASS OF EGGS (grams)MASS AFTER BEING SOAKED IN VINEGARMASS AFTER BEING SOAKED IN SALT WATERINCREASE/ DECREASE OF THE MASS: CalculationsEgg A46.1 g55.5g65.6g18.19%Egg B47.5g54.4g63.8g17.27%Egg C45.7g57.466.5g15.85%Egg D44.5g54.266.5.g22.69%Egg E47.45g57.566.1g14.95%This graph shows the different data for each egg. These are the general trends:The initial mass of the eggs are about the same mass and don’t really vary. Egg D is the exception to this trend because the eggs initial mass was actually lighter than the rest.The mass of the eggs after the vinegar actually increased, but were about the same. The trend line is straight across which shows that they did not vary.The mass after salt water increased slightly, but because of the various different masses at the beginning makes it look like it varies. The % increase generally increased. Egg D increased the most as it was the lightest out of all. CONCLUSIONWhen you put an egg in vinegar, we see that the shell dissolves, but do you ever wonder why? An egg is made mostly out of calcium carbonate which reacts with an ingredient in vinegar, acetic acid. Acetic acid is about 4% of the vinegar and  what breaks apart the solid calcium carbonate crystals. The bubbles we see, from the egg, is the carbonate that make carbon dioxide and the other calcium ions float free. This is the equation:CaCO3 (s) + 2 HC2H3O2 (aq)   ?   Ca(C2H3O2)2 (aq) + H2O (l) + CO2 (g)In the vinegar, the egg’s mass also increased because the vinegar is hypotonic to the solution in the egg, causing water to diffuse into the cell of the egg. This allows the egg to increase in size while the shell dissolves from off the egg.  My hypothesis was correct for this one. These same de-shelled eggs could be good models to represent those of human cells. In an egg, after dissolving the egg shell, a thin membrane remains. This membrane is like our human cells. They are selectively permeable which allows only certain substances to pass through while blocking others. When we put the egg in the salt concentrated water, we saw that the egg started to float. Think of it like this, adding salt to the water makes it like an ocean which is easier to float and swim in than just normal/ distilled water. This is because salt makes water denser. When salt water gets denser, the easier it would be for objects to float on it.   My hypothesis was correct. The water did go inside the egg, but the ones with least salt increased the most, unless the egg was the smallest and it had enough space to take in a lot of extra water. When the concentration of the salt was increased, the amount of water decrease and it is the same the other way around. The mass of the egg will increase if the amount of water is more than the concentration of the salt water and all of this happens because of osmosis. While random molecular motion will cause individual molecules to continue moving back and forth across the membrane, the overall concentration on each side will remain in equilibrium, with equal concentrations on both sides.The egg’s membrane is permeable to water. Movement of a solvent (such as water) across a semipermeable membrane from a less concentrated solution to a more concentrated one is called osmosis. When an egg is soaked in a solution that has a higher solute concentration (the relative amount of dissolved stuff) than the solute concentration inside the egg, water moves out of the egg and into the solution (see diagram below).As a result, the egg loses mass and ends up looking deflated. An egg naturally has a lot of stuff inside, so the outside solution has to be very concentrated for this to happen. That’s the case when an egg is treated with corn syrup or buried in salt. By contrast, when an egg is treated with distilled water, or a dilute salt solution, the solute concentration is higher inside the egg than out, so the water moves into the egg, increasing its mass. It may be easier to think about osmosis in terms of water concentration rather than solute concentration. If the solute concentration is high, then the water concentration will be low by comparison.Rubbing, or isopropyl, alcohol is at least 70% alcohol and therefore less than 30% water. This should cause water to move from the egg into the solution, and the egg should lose mass. In addition, the egg may appear white and rubbery. The plasma membranes of your cells behave much like those of the egg. All of the trillions of cells in your body are like busy seaports with materials coming in and going out. Water, oxygen, and nutrients must pass through the plasma membrane into your cells, and wastes must leave. When the concentration of oxygen is higher in your lungs than it is in your blood, for example, the oxygen diffuses into red blood cells through capillary walls. Your flowing blood then transports that oxygen to your tissues. From there, the oxygen diffuses into other cells to be used in cellular respiration. Through a similar process, water in the stomach moves into the bloodstream and is then carried to the cells, where it supports a variety of essential bodily fun