Step-by-step explanation:
When an unopened bottle of carbonated water appears to contain no gases, it is actually because the gas is dissolved in the water under pressure. This large-scale behavior can be explained by understanding the relationship between pressure, solubility, and the behavior of particles at a small scale.
Carbonated water is typically created by dissolving carbon dioxide (CO2) gas in water under pressure. At a small scale, water molecules form a network of hydrogen bonds, creating spaces where gas molecules can fit. When CO2 is dissolved in water, it forms carbonic acid (H2CO3), which contributes to the slightly acidic taste of carbonated water. The solubility of CO2 in water increases with increasing pressure.
Henry's Law describes the relationship between the solubility of a gas in a liquid and the partial pressure of the gas above the liquid. According to Henry's Law, at a constant temperature, the amount of dissolved gas is proportional to the partial pressure of that gas in equilibrium with the liquid. In the case of carbonated water, when the bottle is sealed, the pressure inside the bottle is higher than atmospheric pressure, and a larger amount of CO2 can dissolve in the water.
When you open the bottle, the pressure inside the bottle rapidly decreases to match the atmospheric pressure. As a result, the solubility of CO2 in the water decreases, and the excess CO2 comes out of the solution in the form of bubbles. This is the fizzing you observe when opening a bottle of carbonated water. At a small scale, the CO2 molecules that were once dissolved in the water now form bubbles, which grow and rise to the surface, eventually escaping into the air.