Egg Lab

The assignment for each group was to test two solutions on two separate eggs and record their results. They had the option of choosing two of the following solutions (one for each egg) to test on their eggs: corn syrup (50 % diluted), alcohol, distilled water, salty water (20% diluted), or tap water. The students would: measure their egg for its mass and circumference, record qualitative observations of the egg, and measure how much water was left in the cup each day, three different days: Thursday, Friday, and Monday. The aim was to investigate the effect of different solutions on an egg’s mass and size. The purpose of the lab was to help students better understand osmosis.

On Wednesday, each group made an outline for which two solutions they would be testing on their egg, and had made hypothesis (based on what they had learned in class) about what would happen to each egg.

 On Thursday (Day 1) each group, of about 3 people, was given 2 eggs (the eggs had already had their calcium shells dissolved in vinegar so the egg’s membrane was exposed). The groups measured their eggs on a scale for mass and with a string for their circumference. The groups recorded any qualitative observations and then sunk their eggs into the solutions for the next day. Finally, they shared results with another group, testing the same solutions on their eggs.

On Friday (Day 2) the groups removed their eggs from the solutions they were in, and again measured their eggs on a scale for mass and with a string for their circumference. They then, again, recorded qualitative observations and put their eggs back into the solutions. After that, they shared results with the same group as the day before.

On Monday (Day 3 [the last day]) the groups repeated what they had done the previous days (measured eggs, made observations, etc.) Then, they popped the membrane of the eggs in a petri dish, and recorded qualitative observations. They shared their results with the same other group, and through their egg away.

My group (me, Rodrigo F., and Lucas) chose to investigate the effects of salty water (20% solution) and distilled water on our eggs.  Our hypothesis was that the egg put in salty water would shrivel and have much less water in it, and that the egg put in the distilled water would expand and burst from having absorbed water. We believed that the egg put in salty water would shrivel and lose water because of osmosis; we believed there would be a greater concentration of water inside the egg than outside, therefore, water would leave the egg until both concentrations were propotionate. We believed that the egg which was put into distilled water would expand and burst from having absorbed so much water also because of osmosis; we believed that the distilled water would have a much higher concentration of water than the inside of the egg (since distilled water is pure water), therefore, all the distilled (pure) water would flow into the egg because it's concentration of water molecules is 100% and as long as the egg has other substances in it, it's concentration of water will never reach 100%. The egg would expand do to how much water had flown in and should then burst because the membrane could not hold anymore water.

These were our results for our egg which was put into the cup with distilled water:

• Quantitative Observations-
  

The Effect of Distilled Water on an Egg
	Day 1	Day 2	Day 3
Volume of Water Left in cup (ml)	80	75	65
Circumference of Egg (cm)	14.9	15	15.5
Egg Mass (grams)	66.52	70.02	75.2



• Qualitative Observations-

The Effect of Distilled Water on an Egg
	Day 1	Day 2	Day 3
Size	Normal/ Average	Semi-Large (More Substance Inside)	Large (More Substance Inside)
Color	Light Orange	Darker Orange (blotchy)	Dark Orange (blotchy)
Other Observations	Feels Rubbery Lines	Feels Rubbery Lines (more defined)	Feels Rubbery Lines

 

• Popped Egg-

After popping the egg which was placed in distilled water, we find various differences than from a regular egg: the egg yolk has a jelly-like texture and the egg white (which is usually clear before being cooked) is white and also has turned to a more solid “jelly” texture.

These were our results for our egg which was put into the cup with salty water:

• Quantitative Observations-

The Effect of Salty Water on an Egg
	Day 1	Day 2	Day 3
Volume of Water Left in cup (ml)	80	71	63
Circumference of Egg (cm)	15.4	15.75	16.1
Egg Mass (grams)	65.74	71.12	73.2

• Qualitative Observations:

The Effect of Salty Water on an Egg
	Day 1	Day 2	Day 3
Size	Normal/ Average	Medium Large (More Substance Inside)	Large (More Substance Inside)
Color	Light Orange	White/ Light Orange	White
Other Observations	Feels Rubbery Lines	Feels Rubbery Lines (fading)	Feels Rubbery

• Popped Egg

After being popped, we see that the egg is not too different from a regular egg.

Analysis:

• Egg in Distilled Water- The egg seems to have absorbed water, but not as much as I expected. The egg is larger both in mass and size and the volume of water left inside the cup has decreased.
• Egg in Salty Water- Contrary to what I believed what happen, the egg actually got larger and seems to have absorbed water. The egg’s mass got greater, along with its circumference.

Conclusions:


Egg in Distilled Water- I believe the water volume in the cup lowered because it was absorbed by the egg. I think the egg grew in mass and size because water flowed into the egg. The egg was completely immersed in distilled water, because of this, the water concentration on the outside was 100% and on the inside it was not which meant that water would continue to flow into the egg until there was no distilled water left on the outside of the egg's membrane or until the egg burst.
Because the water was flowing from higher concentration to lower concentration, we can assume that what happened was due to passive transport; specifically, osmosis. We know it was osmosis because it involved water (a solvent) instead of a solute, so it could not be diffusion.


Egg in Salty Water- I think the water volume in the cup lowered because it was absorbed by the egg. The mass and size of the egg increased also because water was absorbed by the egg. Initially, I believed that the effects of the salty water would be opposite to the results, but after further analyzing it, I understood what actually happened. I realized I had forgotten to take into account that although there was water inside the egg, there were also other substances. Because of this, the concentration of salty water outside the egg (which was 20% diluted) must have actually contained a higher concentration of water than the inside of the egg. After making that realization, we can assume that the water from the salt-water mixture actually flowed into the egg rather than vice-versa.
As this situation involved higher concentration flowing into the lower concentration, we know it was passive transport. We also know it involved the transport of water into the egg, and so we can further specify the method of passive transport to be osmosis.

Apparatus:

Procedure

• Liquid may have spilled out of the cup when transferring it back and forth between the graduated cylinder, beaker, cup, etc.
• Liquid may have been left inside some of the equipment (graduated cylinder, beaker, cup, etc.)
• Liquid may have evaporated over night.
• Liquid may have dripped off the egg whenever it was taken out of the egg.
• It was hard to tell how much liquid was left in the graduated cylinder because there was foam near the meniscus.

A funnel could be used to help ensure that all of the liquid makes its way back to the cup after being measured in the graduated cylinder. We could have shaken whatever we were trying to transfer liquid from to try to get as much of the liquid out as possible. A lid could be put over the cup overnight so that liquid could not evaporate. The egg could have been shaken and some of the excess water could be wiped off the egg back into the cup.


Equipment

• The string was easily able to stretch a few millimeters.
• The cup was narrow which allowed the egg to touch the edges and have to squeeze which may have altered the results.

We should have used a string that was not easliy streched or made of a different material. We could have put the egg in a broader cup.


Team Evaluation- I believe my team worked really well. Lucas was always ready to volunteer to fetch equipment, perform tasks, and was overall very engaged. Rod F. was always on task; he was responsible during the experiment and did everything very efficiently. Overall I think we did a good job working together and got through the lab having done things correctly and efficiently.
 What I Learned- After having done this lab, I learned more about the importance of carrying out experiments instead of just assuming the results because of what I already know; my results for the salty water egg were the exact opposite of what I said would happen in my hypothesis (I thought the egg would shrivel but it actually expanded). In addition to that, I am also able to better understand osmosis; with a hands-on experiment, the experience of the egg lab really helped me to see osmosis in action.




Osmosis in Action- Osmosis affects all living things. We, for example, use osmosis to be able to absorb water. When water enters our body, it travels to our large intestine. There, it is absorbed, first by passive transport (osmosis) then by active transport. The water is absorbed by osmosis because there is a larger concentration of water in the large intestine than in the blood stream, but then when the concentrations are balanced, we need active transport to absorb the rest of the water. Once the water has made it to the blood stream, it is then distributed to the cells because there is a higher concentration of water in the blood than in the cells.
Another place osmosis occurs in our bodies is in our kidneys. If osmosis didn't occur, we would not be able to retain water because the water which was mixed with the wastes would have no way to reenter our bloodstream. When we drink alcohol, the pores in our kidney's are closed so we cannot retain much water and we waste a lot.