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Osmosis Egg Lab

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by

Jeyashree Haridoss

on 4 March 2013

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Transcript of Osmosis Egg Lab

Videos 0 + - = 9 8 7 1 2 3 4 5 6 c Problem and Background Information Bibliography Postlethwait, John and Hopson, Janet.
Modern Biology. Austin, Texas: 2006 Osmosis Egg Lab Problem Background Information Hypothesis #1 Hypothesis #2 Materials Procedure Analysis Data Table 1) First soak the egg in a tub of vinegar (make sure the egg is covered) for 48 hours to dissolve the shell; rotate the egg every 12 hours for equal coverage.
2) After 48 hours has passed, remove the egg from the vinegar solution and rinse it off gently.
3) Place the egg in a 250 mL beaker and fill with 150 mL of corn syrup and 50 mL of water. When filling note to pour the corn syrup and water over the egg until it reaches these marks on the beaker, not to measure them outside and pour in, as the amount of liquid is not exactly 150 and 50 mL with the displacement of the egg in the beaker. Check the egg in 24 hours
4) Gently remove egg from the beaker, rinse it off, and clean out the beaker. Weigh and measure circumference. Record data in data table.
5) Place the egg back in the beaker and fill with 200 mL of water (pouring over the egg, the same as step 3). Check in 24 hours.
6) Repeat step 4
7) Clean-up all materials and dispose of the egg properly. How can we observe osmosis across a semi-permeable membrane? Variables Independent Variable: Type of Solution- Corn Syrup (Hypertonic) or Tap Water (Hypotonic)
Dependent Variable: Circumference (cm) and Mass (g)
Constants: Size of the beaker, same egg in all environments, amount of total liquid (200 mL), amount of time the egg is left in each solution Groups Experimental Group: the egg in the corn syrup (hypertonic) and tap water (hypotonic) solutions
Control Group: the egg in the vinegar (isotonic) solution If we soak the egg in a hypertonic solution, in this case corn syrup, then the egg will shrink and shrivel up because the water inside the egg will diffuse out to try to even out the concentration inside and outside of the cell or to try and reach equilibrium, equal movement of water into and out of the cell. If we soak the egg in a hypotonic solution, in this case tap water, then the egg will swell because water from outside of the egg will diffuse into the egg to try to equal the concentration of water inside and outside of the egg or to try and reach equilibrium, equal movement of water into and out of the cell. By Eunice Seo, Madeline Clark, Stephiya Sabu, and Jeyashree Haridoss Osmosis is the diffusion of water across a semi-permeable membrane. A semi-permeable membrane will only let certain substances through. In osmosis, it lets only water through. Diffusion is a type of passive transport which means it requires no energy and the molecules flow with the concentration gradient; high concentration of water to low concentration of water. There are three types of solutions you can put a cell (or in this case, an egg) in: isotonic, hypotonic, and hypertonic.
Isotonic solutions have a concentration of water/ solvent equal to that of inside the cell. It's the ideal environment for animal cells but plant cells become flaccid because there's not enough turgor pressure to keep it rigid. Hypotonic solutions have a concentration of the water/ solvent greater than that of inside the cell. Water moves in and animal cells burst/ lyse. Plant cells, however, are turgid, or at their ideal state.
In hypertonic solutions, water moves out of the cell because the concentration of water/ solvent is less than that of inside the cell. Animal cells will shrivel and plant cells plasmolyze or wither. The data supports our first hypothesis which stated that.... The original
mass and circumference was... After submerging the egg in the corn syrup and tap water solution for 24 hours, the egg's mass reduced to.... and the circumference reduced to... There was a decrease of 24.2% in mass and 12.2% in circumference. The water had diffused out of the egg and into the corn syrup in order to reach equilibrium. 1 Chicken egg (white)
Vinegar
Plastic tub
Solution 1: Corn Syrup
Solution 2: Tap Water
1 glass 250 mL beaker
String or yarn
Ruler
Scale that measures in grams 1) The independent variables were the types of solution used to soak the egg in. They are corn syrup and tap water. The dependent variables were the circumference and mass of the egg after being put into each solution.
2) The control group was the egg in vinegar, which is the isotonic solution. We need a control group so we can measure how the egg changes from it's original mass and circumference. If our control group was not an isotonic solution, then our data would not be accurate because it wouldn't have started from a "normal" place.
3) The egg swelled in the hypotonic (tap water) solution because there was a higher concentration of water outside that moved into the egg to reach equilibrium.
4) The egg shrunk in the hypertonic solution (corn syrup) because there was a low concentration of water outside the egg.
5) The results that I discussed in questions 3 and 4 do support the hypotheses. The first hypothesis states that if the egg is put into a hypertonic solution, then it will shrivel. The data shows that when it was put into the corn syrup, which was the hypertonic solution, the mass and circumference decreased. The second hypothesis states that if the egg is put into a hypotonic solution, then the egg would grow large. The data shows a dramatic increase from when it was in the hypertonic solution to the hypotonic solution.
6) Osmosis is the movement of water across a selectively permeable membrane. It is passive transport, which requires no energy and the substances move from high to low.
7) Passive and active transport methods are different. Active transport requires energy, it moves from low to high concentration, and it can use vesicles to bring substances in and out. Active however, does not use energy and moves molecules from high to low concentrations.
8) An experimental error that we had was that the egg membrane did not fully dissolve. This may have caused the water that was coming or going out to not have access to the entire surface area of the membrane. This error did not affect the outcome because in the hypotonic solution, the egg became large and in the hypertonic solution, the egg shriveled. The data supports our second hypothesis which stated that... We compared Day3's data to Day 2. The egg's mass in Day 2 was... and the circumference was... After submerging the egg in the tap water for 24 hours, the mass increased by 38.3%. It became.... The circumference was reduced by 17.2% and became... This swelling of the egg was caused by the water diffusing into the egg in order to reach equilibrium. If you compare Day 3's data to our control group, the egg's mass is 14.1% larger and egg's circumference is 5% larger. Sources of Error A possible source of error is the shell membrane of the egg was not completely dissolved by the vinegar, leaving a thicker membrane for the water molecules to travel through. This may have decreased the percent change in mass and circumference but I doubt it affected the overall outcome: the egg in corn syrup shrunk and the egg in tap water swelled. Conclusion Thanks for watching!
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