Introduction
Osmosis... One of the most difficult topics to understand in science class this year. Many of us in the class were confused how it worked and what it depended on to work and how it would affect a cell. Questions were rushing in our heads constantly and the answers would come in rather complex manners. Our teacher, Ms. Silva, introduced an experiment where we would learn how osmosis worked by utilizing an egg resembling a cell. We were given one goal; to see how osmosis worked in eggs submerged in different substances.
In the past few days in Science class, we were set into groups of three (more or less), in which I was put next to Allie and Arthur, and given the objective to analyze, observe and record data about two eggs being submerged in 80mL of a substance (being Alcohol, Corn Syrup, Distilled Water, Salt Water) and left there for 2 days so the substance could react with the egg. My group and I were assigned the ALCOHOL and SALT WATER (20%) substances. Before leaving the egg in the beaker with one of the 4 substances, we drowned the egg in a container with vinegar so it would dissolve the shell since the acid would slowly break down the calcium that composed the hard shell. This project was produced so we could get a notice how osmosis works; the egg would resemble a cell. The main objective was to see how the substance would affect the egg. For example, would the egg get smaller, harder, would it be softer, would the liquid amount increase or decrease? My prediction for the alcohol egg was that it would be bigger and heavier, since the alcohol would replace water and it weighs more. For the salt water I predicted that I would be larger and a lot softer than usual, since the salt water would take over the inside of the egg.
Processes:
In DAY ONE of the experiment, we measured the circumference and the mass of our eggs and later on put them inside the cups that contained 80mL of Alcohol and Salt Water. We left the eggs inside those cups until the following day.
In DAY TWO of the experiment, we took out the eggs, carefully so we wouldn’t pop the fragile skins, and analyzed the eggs once more. We took note of the texture, smell, appearance and made sure we had seen if the liquid volume increased or decreased. The egg soaked in alcohol already began smelling like alcohol itself, and it felt hard but not stone-like. We could drop it on the table and it could bounce 3 or 4 times. However, the salt water egg seemed to be almost like a clear plastic securing water inside it; in other words, it was unbelievably fragile and one single scrape of our nails could rupture the fragile skin around the yoke. It contained no particular smell. We wrapped everything up and returned the egg inside the cups and left them there for the next day.
On the last day, my team and I took the eggs out from the cups one last time, checked the circumference, mass and the amount of liquid left in the cups, and observed the changes in appearance and texture and smell. The alcohol egg was looking just like a naturally boiled egg but eating would not be the best choice; you could tell that by the strong stench of alcohol that it emitted. It was harder than the day before since the alcohol penetrated the “membrane” overtime. The salt water egg was as soft as a piece of chewed gum. My group and I could identify that the salt water had traveled inside the egg since it was increased in size and the liquid (salt water) that was inside the beaker reduced significantly. We later "dissected" these eggs, cutting into both of them and analyzing the outcome of having them stay inside a cup with either alcohol or salt water. The alcohol egg was looking exactly like a boiled egg, with the yoke being solid. But the smell of alcohol was greater than before. The salt water egg literally exploded as Arthur and I drove our knifes into it. The excessive water inside it caused it to become a watery mess as the yoke mixed with the salt water.
CONCLUSION
ALCOHOL EGG:
The alcohol egg got smaller but lighter (from 14 cm to 16.5 cm and from 73g to 64g). This means that most of the water inside the egg escaped, decreasing its size, and a lot of alcohol, which is much heavier than water, got into it. The loss of liquid volume (from 80mL to 51mL) could be caused by the simple fact of evaporation. From what I’ve learned, alcohol evaporates quicker than water. Since we did not seal the tops of our beakers, most of the liquid could have been evaporated. The warm temperature could have caused this to happen faster. As to the appearance of a boiled egg, this could be caused by the strong acid alcohol contains, which led to chemical reactions that made the egg seem “boiled”. My prediction was completely wrong.
SALT WATER EGG:
The salt water egg did the exact opposite; it got larger and heavier (from 13.5cm to 17.5cm and from 62g to 83g). Since there was no salt inside the egg, the salt water entered it freely and intensively. You could actually notice the amount of water inside the egg since it became transparent. The amount of liquid also decreased because of the same reason as the alcohol egg and because most of the liquid went into the egg. My prediction was right for this egg.
Osmosis can be negatively affecting an organism. This could happen simply when we are at the pool or a blistering hot summer day and our hands become wrinkled, meaning we lost some water and are a bit dehydrated. This won’t bring much damage to us, but long hours in a sea can potentially dehydrate us. If we do not hydrate ourselves quickly, we can die of dehydration.
Evaluation
The possible sources of error during the experiment are:
- Evaporation of the liquids
- Passing of liquids from beaker to cylinder
-Wrong measurements
- Passing of liquids from beaker to cylinder
-Wrong measurements
To fix these errors we needed to be a bit more careful of what we were doing. For example, we could cover the lids of the each and every cup we held our eggs in. The passing of the liquids would be fixed by grabbing a spoon and forcing all the liquid down. He wrong measurements is a matter of lack of attention of focus.
Working with this group was both well-balanced and a good experience. They are loyal and hard-working friends and I hope I have them as my next science group.
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