Nick Colvin
Honors Biology
Miss Maioriello
September 30
Introduction:
1 Diffusion is the process by which molecules spread from an area of a higher concentration to an area of lower concentration. Diffusion continues until it reaches equilibrium (Both sides of the membrane have an equal concentration). 1 Osmosis is the process in which water moves across a membrane and goes to the higher concentration of solute (lower concentration of water) from the lower concentration of solute. 2 Osmosis was discovered by a man named Henry Dutrochet, it is also a natural process that makes life possible. Also, both diffusion and osmosis go with the concentration gradient. In the experiment we also used a shell-less egg which was surrounded by vinegar. 3 The membrane is left intact is because inside the vinegar is acetic acid which breaks down the egg shell which is made of calcium carbonate. The calcium ions float into the vinegar and the carbonate turns into carbon dioxide, leaving you with a shell-less raw egg. In this case, this was a hypotonic solution due to the egg expanding and also, a higher concentration of water outside of the membrane and a lower concentration of water on the inside (osmosis).
Objective:
To use the properties of both diffusion and osmosis to see the affects of either maple syrup or water on a shell-less raw egg over a three day period. Also, applying properties hypotonic, hypertonic, and isotonic solutions.
Hypothesis:
If the egg is placed in water, through osmosis the shell-less raw egg will increase in both size and mass and possibly lyse.
Material List:
– Raw shell-less egg
– Water
Beaker 450milliliters Pancake Syrup Scale Saran (plastic) Wrap Labeling Tape Data Tables Pen or Pencil
Procedure:
Place raw egg in vinegar until shell-less Take mass of raw shell-less egg. Fill beaker with 450 milliliters of selected solution. Label with tape and name Cover with Saran Wrap. Check back every 24 hours. Weigh egg by taking it out of the solution. Take notes, observations, and mass everyday. Repeat steps 6 and 7 twice more. After experiment clean all items used thoroughly and dispose egg correctly.
Data/Results/Observations:
Day 1:
On the first day you could see through the raw egg’s membrane but it was slightly blurry. When the egg was placed in the water the volume went from 450mL to 530mL. The egg is similar to a water balloon, puffy and light. You could also see the yellow yoke in the center.
Day 2:
The egg has increased in size and mass. The yoke is more clear and easier to see. Egg has thickened and has changed color from clear to a yellowish white. The outer part of the cell is softer. The egg is squishy and seems as if it could pop.
Day 3:
The egg is slightly smaller. Feels very much like yesterday, soft and balloon like. It has started to smell like vinegar again. The egg’s yoke is not visible very well and the egg is mostly yellow with small spots that are clear.
Table 1: Egg Mass Over a Three Day Period
Day 1
Day 2
Day 3
Egg Mass (g)
81.8g
86.8g
83.2g
Table 2: Volume of Water for Three Days with Egg
Table 3: Volume of Water for Three Days without Egg
Day 1
Day 2
Day 3
Volume of Water without Egg
450mL
440mL
440mL
Equations:
Final-Initial ÷ initial x 100
83.2-81.8= 1.4
1.4 ÷ 81.8 = 0 .0171149144
0.0171149144 x 100 = 1.71149144
Conclusion:
The purpose of this experiment was too use our knowledge of osmosis and diffusion and apply it to a raw shell-less egg and how it reacts to being submerged in water or pancake syrup. The hypothesis made from this experiment was that when a raw shell-less egg is placed under water, that it would expand and have a chance of lyse. This was proved correctly as clearly shown in Table 1 the egg weighed more on day 2 and 3. Although it didn’t lyse or pop, it did however increase as expected. It could be concluded from our tests that the mass went down on the last day due to the egg being full of water, through osmosis it pumped water out through the membrane of the egg and thus, making the egg weigh less and look smaller. The hypothesis cannot be considered completely correct unless there are no errors or disturbances throughout the experiment. In this lab, there were several possibilities of errors occurring. The egg could’ve been warped or distorted in such a way when placed on the scale that it would increase the mass of the egg. The scale could’ve not been zero’d and given an incorrect reading. Another possibility is, if the eggs shell wasn’t completely gone, then water wouldn’t have been able to go through the membrane evenly. Ways to work away from making such errors in the future is to inspect all materials before hand and be sure to follow directions carefully and as directed.
Work Cited
1 Miller, Kenneth, and Joseph Levine. Prentice Hall: Biology. Saddle River, New Jersey: Pearson Education, Inc., 2002. 184-189.
2 Richet, Gabriel. “The osmotic pressure of the urine-from Dutrochet to Korányi, a trans‐European interdisciplinary epic.” Oxford . N.p., 2011. Web. 24 Sep 2011. ndt.oxfordjournals.org/content/16/2/420.full>.
3 Gable, Lisa. “Home Experiments.” Science Junction. N.p., 11/22/98. Web. 24 Sep 2011. station/experiments/EGG/egg.html>.