Naked Egg Experiment and Cleaning Hard Water Spots
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Naked Egg Experiment and Cleaning Hard Water Spots
My kids have recently started learning the dreaded chore of cleaning their bathroom. They use distilled white vinegar (4-5% acetic acid) because it is a versatile and effective cleaning product for them to practice with. Recently, when inspecting the completion of their work I noticed there wasn’t a strong vinegar smell. Come to find out, they refilled the Vinegar spray bottle with water when it got low. I tried to explain that vinegar has both antibacterial properties as well as the ability to break down hard water deposits. They insisted the water worked just as well.
We then set out to explore some of the properties of vinegar compared to water and some other cleaning products. One experiment was the effect of vinegar on hard water. Since hard water is largely negatively charged calcium ions we then conducted the naked egg experiment using vinegar, water and my preferred cleaning product (Mrs. Meyer’s) to see which one was most effective at dissolving the calcium carbonate egg shell. We had a hypothesis that whichever cleaning product dissolved the egg shell most quickly would also be the best of our products for treating the hard water spots in our bathrooms.
We then set out to explore some of the properties of vinegar compared to water and some other cleaning products. One experiment was the effect of vinegar on hard water. Since hard water is largely negatively charged calcium ions we then conducted the naked egg experiment using vinegar, water and my preferred cleaning product (Mrs. Meyer’s) to see which one was most effective at dissolving the calcium carbonate egg shell. We had a hypothesis that whichever cleaning product dissolved the egg shell most quickly would also be the best of our products for treating the hard water spots in our bathrooms.
Supplies
Three equal size glass cups
3 eggs of similar size
White distilled vinegar
Mrs. Meyer’s cleaning (diluted 1/4 Mrs. meyers to1 gallon water)
Water
3 of our bathroom sink faucet aerators
Naked Egg Method
Place 1 1/2 cups of Meyer’s cleaning in glass 1
Place 1 1/2 cups of vinegar in glass 2.
Place 1 1/2 cups of water in glass 3.
Place an egg in each cup
Inspect at 4, 12, and 24 hrs.
Place 1 1/2 cups of vinegar in glass 2.
Place 1 1/2 cups of water in glass 3.
Place an egg in each cup
Inspect at 4, 12, and 24 hrs.
Naked Egg Results
Immediately the egg in the vinegar had bubbles surrounding it while the other two remained unchanged.
4 hrs - egg in the vinegar was surrounded by bubbles and floating while the other two eggs were at the bottom of their glasses and appeared unchanged.
12 hrs - egg in vinegar appears to have a yellow streak. It is still surrounded by bubbles and floating. Other two eggs unchanged
24 hrs - The egg in vinegar is still floating and surrounded by bubbles. It completely lost its hard out shell and all that was left surrounding the egg was a transparent membrane. It is also larger than the other eggs now. The other two eggs look unchanged.
4 hrs - egg in the vinegar was surrounded by bubbles and floating while the other two eggs were at the bottom of their glasses and appeared unchanged.
12 hrs - egg in vinegar appears to have a yellow streak. It is still surrounded by bubbles and floating. Other two eggs unchanged
24 hrs - The egg in vinegar is still floating and surrounded by bubbles. It completely lost its hard out shell and all that was left surrounding the egg was a transparent membrane. It is also larger than the other eggs now. The other two eggs look unchanged.
Naked Egg Conclusion and Science
The vinegar was the most effective of our cleaning products at dissolving the calcium carbonate egg shell. Vinegar is a weak acid of 4-5% acetic acid in solution. When it comes in contact with the calcium carbonate it protonates the carbonate portion of the calcium carbonate creating carbonic acid and calcium acetate. The carbonic acid is unstable at room temperature and quickly breaks down to form carbon dioxide and water.
2 CH3(COOH) + CaCO3 => H2CO3 + Ca(CH3COO) => CO2 + H2O+ Ca(CH3COO)
Acetic acid (aq) + calcium carbonate (s) => water (l) + carbon dioxide (g) + calcium acetate (s)
The product calcium acetate is solid but is soluble in water. So the final products are the membrane enclosed egg and the aqueous solution of water and calcium acetate. The carbon dioxide gas eventually rises to the top of the solution and is released into the air.
Two observations to be explained. First, the egg in vinegar was surrounded by bubbles and floated. My kids surmised the egg floated because it was lighter while losing its hard shell. The bubbles were actually the CO2 (gas) which is less dense than liquid water. As a result the gaseous CO2 rises and pulls the egg upward with it. Once we removed the egg from the solution and cleaned it off we placed it back into the vinegar solution. Since the CO2 wasn’t surrounding the egg anymore it sunk to the bottom.
The second observation was that the final egg was somehow larger and heavier than the original. The explanation is that osmosis occurred across the membrane. At the start of the experiment the water inside the egg was less than the water outside the egg. Once the egg shell was dissolved the water outside the egg diffused across the membrane until equilibrium occurred. The water diffuses across the membrane from an area of high concentration to a lower concentration until they are in a flowing equal state (equilibrium).
2 CH3(COOH) + CaCO3 => H2CO3 + Ca(CH3COO) => CO2 + H2O+ Ca(CH3COO)
Acetic acid (aq) + calcium carbonate (s) => water (l) + carbon dioxide (g) + calcium acetate (s)
The product calcium acetate is solid but is soluble in water. So the final products are the membrane enclosed egg and the aqueous solution of water and calcium acetate. The carbon dioxide gas eventually rises to the top of the solution and is released into the air.
Two observations to be explained. First, the egg in vinegar was surrounded by bubbles and floated. My kids surmised the egg floated because it was lighter while losing its hard shell. The bubbles were actually the CO2 (gas) which is less dense than liquid water. As a result the gaseous CO2 rises and pulls the egg upward with it. Once we removed the egg from the solution and cleaned it off we placed it back into the vinegar solution. Since the CO2 wasn’t surrounding the egg anymore it sunk to the bottom.
The second observation was that the final egg was somehow larger and heavier than the original. The explanation is that osmosis occurred across the membrane. At the start of the experiment the water inside the egg was less than the water outside the egg. Once the egg shell was dissolved the water outside the egg diffused across the membrane until equilibrium occurred. The water diffuses across the membrane from an area of high concentration to a lower concentration until they are in a flowing equal state (equilibrium).
Bathroom Fixture Calcium Build Up
We then placed our bathroom faucet aerators with calcium build up in one of each cleaning solution. Our hypothesis was, the vinegar would be most effective at cleaning the hard water because it was most effective at dissolving the calcium carbonate egg shell.
We placed the aerators in equal amounts of the three solutions for 4 hrs. Right away we could see tiny gas bubbles from the aerator in the vinegar.
Both the water and Mrs. Meyer’s cleaning had no effect on the hard water build up. The vinegar had excellent results breaking up the white water deposits.
Our conclusion was that the vinegar was the most effective cleaning agent we had for hard water spots.
(M=Mrs. Meyer’s, V = vinegar, W = water)
We placed the aerators in equal amounts of the three solutions for 4 hrs. Right away we could see tiny gas bubbles from the aerator in the vinegar.
Both the water and Mrs. Meyer’s cleaning had no effect on the hard water build up. The vinegar had excellent results breaking up the white water deposits.
Our conclusion was that the vinegar was the most effective cleaning agent we had for hard water spots.
(M=Mrs. Meyer’s, V = vinegar, W = water)