In theory, if you put water in the vacuum packaging bag, the amount of water will not decrease. This is because water molecules are in a vacuum without the influence of external pressure, so they cannot evaporate or transform into gaseous form. However, in practice, water may weigh less in the vacuum bag. This phenomenon will be explained from two perspectives of physics and chemistry.
The physical angle of the vacuum packaging bag
As the air in the vacuum packaging bag is drawn out, the pressure will drop, which will allow gas-dissolved substances in the water, such as oxygen and carbon dioxide, to escape the water column. This process is called gas dissolution. Gas dissolution is a natural process that causes a body of water to lose weight, but it doesn’t mean that the water molecules themselves disappear. Therefore, it is best to degas the water as much as possible before filling it into the vacuum packaging bag.
Another factor that affects the weight of a body of water is the vapor pressure in the water. Vapor pressure is the pressure exerted by water molecules when they change from liquid to gas. In a vacuum bag, the vapor pressure in the water increases due to the absence of external pressure. This causes water molecules to escape from the water body, further causing the water to lose weight. Therefore, when storing water in a vacuum bag, make sure the bag is well sealed to minimize the escape of water molecules and gas dissolution.
Chemical angle of vacuum packaging bag
In addition to physical factors, chemical factors also affect the weight of water in a vacuum bag. The bond between a hydrogen atom and an oxygen atom in a water molecule is a polar molecular bond, so water molecules can form hydrogen bonds. These hydrogen bonds can bring water molecules together, forming clusters. In a vacuum bag, due to the absence of external pressure, the interaction between water molecules increases, which leads to the formation of water clusters. Such clusters increase the density of the water, causing the water to gain weight.
Another chemical factor is the pH of the water. In a vacuum bag, the pH of the water may change due to enhanced interactions between water molecules. Changes in pH may cause chemical reactions in water molecules, such as ionization of water and redox reactions of water molecules. These reactions may affect the weight of the water.
To sum up, the water in the vacuum bag may lose weight due to the dissolution of gas and the escape of water molecules. When storing water in a vacuum bag, degas the water as much as possible and make sure the bag is well sealed to minimize the escape of water molecules and gas dissolution. Also, due to enhanced interactions between water molecules, the density of water may increase, resulting in an increase in water weight.
