Sparkling water is made bubbly by dissolving carbon dioxide gas into water under specific conditions, which then escapes as bubbles when conditions change.
The fundamental process involves infusing water with carbon dioxide gas. This is achieved through a combination of high gas pressure and low temperature. These conditions force the carbon dioxide to dissolve effectively into the water, forming carbonic acid.
According to the provided reference, the key to getting the bubbles to appear is the change in these conditions: "When the temperature is raised, or the pressure is reduced, carbon dioxide escapes from the water in the form of bubbles."
The Science Behind the Bubbles
Let's break down the process:
-
Getting the Gas In:
- Water and pure carbon dioxide gas (CO2) are combined.
- High pressure is applied above the water's surface, pushing the CO2 molecules into the liquid.
- Keeping the water cold helps more CO2 dissolve because gases are more soluble in liquids at lower temperatures.
- This dissolved CO2 reacts slightly with water to form carbonic acid (H₂CO₃).
-
Making it Bubbly (Releasing the Gas):
- Once the high pressure is released (like opening a bottle or can), or the water warms up, the CO2 becomes less soluble.
- The dissolved CO2 molecules no longer want to stay in the water.
- They cluster together and form gas bubbles.
- These bubbles then rise to the surface and escape.
In essence: The bubbles you see and feel are the carbon dioxide gas that was forced into the water under pressure and cold temperatures, now escaping as the pressure decreases or the temperature increases.
Factors Affecting Bubbles
Several factors influence how bubbly sparkling water is and how long it stays that way:
- Pressure: The higher the initial pressure during carbonation, the more CO2 is dissolved, resulting in more bubbles when opened.
- Temperature: Colder sparkling water retains its carbonation better. As it warms, more CO2 escapes, making it go flat faster.
- Nucleation Sites: Rough surfaces inside a glass, tiny impurities, or even the walls of the container provide spots (nucleation sites) where CO2 molecules can easily gather to form bubbles. This is why bubbles often stream from specific points in a glass.
Summary Table
| Condition | Effect on CO2 Solubility | Outcome |
|---|---|---|
| High Pressure | Increases | CO2 dissolves into water |
| Low Temperature | Increases | More CO2 dissolves into water |
| Reduced Pressure | Decreases | CO2 escapes as bubbles |
| Raised Temperature | Decreases | CO2 escapes as bubbles |
Understanding this process helps explain why an open bottle of sparkling water left at room temperature quickly loses its fizz – the pressure has been reduced, and the temperature is likely higher than when it was bottled, causing the dissolved CO2 to escape rapidly.
