How It Works: The egg is denser than the fresh water (more molecules per square inch), this causes it to sink. When you start dissolving salt in the water, this is increasing the density (adding more molecules per square inch). Eventually the water becomes denser than the egg causing the egg to float.
The explanation behind this phenomenon is simple - DENSITY! In the Salt Water Egg experiment, you have observed that the egg placed in saltwater floated and the one in tap water didn't. Because saltwater is denser than fresh water, the egg does not end up sinking like it usually does!
The density of the average egg will be slightly greater than that of water, so it will sink. To make the egg float, we have to make the water more dense by adding salt. For 1 cup of water, adding 3 tbsp. of salt should be about enough to make the egg float.
When enough salt is added to the water, the saltwater solution's density becomes higher than the egg's, so the egg will then float!
Simply fill a bowl with cold tap water and place your eggs in it. If they sink to the bottom and lay flat on one side, they are fresh and good to eat. A bad egg will float because of the large air cell that forms at its base. Any floating eggs should be thrown out.
Information. An egg can float in water when its air cell has enlarged sufficiently to keep it buoyant. This means the egg is old, but it may be perfectly safe to use. Crack the egg into a bowl and examine it for an off-odor or unusable appearance before deciding to use or discard it.
If they are less fresh but still good to eat, they will stand on one end at the bottom. If they float to the surface, they are no longer fresh enough to eat. This is because as the egg gets older, the size of the air sac inside increases, making it float.
As the density of strong salt solution is denser than fresh water, it exerts more upthrust on the egg that balance the weight of the egg hence the egg sinks in fresh water but floats on a strong salt solution.
A fresh egg sinks in pure water, whereas it floats in saturated salty water.
How It Works: The egg is denser than the fresh water (more molecules per square inch), this causes it to sink. When you start dissolving salt in the water, this is increasing the density (adding more molecules per square inch). Eventually the water becomes denser than the egg causing the egg to float.
Do fertile eggs sink or float? Eggs sinking or floating is nothing to do with fertility – it's to do with freshness. The older an egg is, the more it will float. So a fresh egg will sink; the more it tilts upwards or even floats, the older it is.
You're probably getting the picture by now: a fresh egg sinks in pure water because it is more dense than the water, but can float when the liquid itself has increased in density. This happens when salt is dissolved in the water – the density increases and eventually exceeds that of the egg.
Using this DIY Reddit post as a guide for desired salinity, I calculated how many pounds of salt per gallon is used to help you float. You should use just over six pounds of salt per gallon, according to this, to be able to hang at the surface of the water freely.
If the eggs sink to the bottom and lay flat on their side, they're still fresh. However, if they sink, but stand on one end at the bottom of the glass or bowl, they're not as fresh but still edible. Of course, if any eggs float to the top, they shouldn't be eaten.
In short, you can eat eggs two months out of date. It'll be fine. If you eat an outright bad egg, that's a different story. Eggs pretty exclusively spoil from contamination, and the signs and symptoms are pretty clear if you consume an egg that's been harboring salmonella.
If it sinks or stays at the bottom, it is still fresh. An older egg will either stand on its end or float. The float test works because air builds up inside the egg as it ages, increasing its buoyancy. However, an egg that floats may still be safe to eat, according to the United States Department of Agriculture (USDA).
Decomposition gives off gases. As more of the egg decomposes, more of its mass is converted to gases. A gas bubble forms inside the egg so an older egg floats on its end.
Temperature will definetly have an effect on the buoyancy of the egg and the salt-holding capacity of the water, so, in an ideal world, it would have been held constant, making it a controlled variable.
The best way to determine if your egg is spoiled is by cracking it open into a bowl. If the egg white is pink or iridescent this is an indication of spoilage due to Pseudomonas bacteria. Some of these bacteria can make us sick when eaten and they will produce a greenish, fluorescent, water-soluble color.
As long are they are kept refrigerated at 45 °F or lower, fresh shell eggs are safe to be consumed four to five weeks beyond the carton's Julian date (the date eggs were packed).
Off-color egg white, green or iridescent – Spoilage due to Pseudomonas bacteria, a very common type of bacteria that healthy people often carry without knowing it. This bacteria produces a greenish, fluorescent, water-soluble pigment in the egg white.