Why does an egg gain mass in water?


Eggs are a popular food item that can be prepared in a variety of ways. While it is common knowledge that eggs are made of protein, it is interesting to consider how the properties of water affect the egg when it is submerged. The question arises, why does an egg gain mass in water?

What is an egg made of?

Eggs are made of several components, including the yolk and the white, which are rich in protein. The yolk is also high in fat and cholesterol, while the white contains water, protein, and minerals. The eggshell provides protection to the contents of the egg and is permeable, allowing air and moisture to pass through.

Properties of water

Water is a polar molecule, meaning it has both positively and negatively charged ends. This property allows water to form hydrogen bonds with other molecules, including itself. Water also has a high specific heat capacity, which means it can absorb a lot of heat without increasing in temperature. It is also an excellent solvent, dissolving many substances, including salts and sugars.

How does water interact with an egg?

When an egg is submerged in water, the water molecules begin to seep through the eggshell, hydrating the proteins in the egg white. This hydration causes the egg white to expand, leading to an increase in mass. The yolk, on the other hand, maintains its size and shape as it is less affected by the water due to its higher fat content.

Why does an egg gain mass in water?

The egg gains mass in water due to osmosis. Osmosis is the movement of water molecules from an area of high concentration to an area of low concentration across a semi-permeable membrane. In this case, the egg white acts as the semi-permeable membrane, and the water moves from outside the egg to the inside, causing the egg to gain mass.

The role of osmosis

Osmosis is a critical process that occurs in living organisms. It is responsible for the movement of water and other substances across cell membranes, allowing cells to maintain their shape and function. In the case of the egg, osmosis plays a role in regulating the hydration and expansion of the egg white.

The importance of the egg’s membrane

The egg membrane plays a crucial role in regulating the movement of water and other substances in and out of the egg. It is semi-permeable, allowing water to pass through while preventing the entry of harmful bacteria and viruses. The membrane also helps to maintain the structural integrity of the egg, preventing it from collapsing due to the expansion of the egg white.

Other factors that influence egg mass in water

Other factors that can influence the mass of an egg in water include the temperature of the water, the age of the egg, and the presence of impurities in the water. Warmer water can increase the rate of osmosis, causing the egg to gain mass more quickly. Older eggs may have a thinner membrane, making them more susceptible to water loss or gain.

Real-life applications

Understanding the relationship between water and egg mass has real-life applications. In the food industry, it is important to know how eggs behave when submerged in water to ensure they are of high quality. In science classrooms, this phenomenon can be used to teach students about osmosis and the properties of water.


In conclusion, eggs gain mass in water due to the process of osmosis. The egg white, being a semi-permeable membrane, allows water molecules to pass through, causing the egg to gain mass. The egg membrane plays an essential role in regulating water movement and maintaining the structural integrity of the egg. Understanding this phenomenon has practical applications and can be used to teach important scientific concepts.

Leave a Reply

Your email address will not be published. Required fields are marked *