what makes soda fizz

Soda fizzes because it’s packed with dissolved carbon dioxide gas that escapes as bubbles when the pressure is released.

The basic science

Inside a sealed soda can or bottle, manufacturers force carbon dioxide (CO₂) into the liquid under high pressure, which makes the drink “supersaturated” with gas. When you open it, the pressure suddenly drops, and the CO₂ is no longer as soluble, so it rushes out of the liquid as bubbles.

Why the bubbles form

CO₂ doesn’t just appear as bubbles everywhere at once; it needs tiny starting points called nucleation sites. These are microscopic scratches on the container, dust particles, or even rough spots on ice or sugar grains where CO₂ can gather and grow into visible bubbles that rise and pop at the surface.

The tingle and the taste

Some of the dissolved CO₂ reacts with water to form a weak acid called carbonic acid, which adds a sharp, slightly tangy bite to soda. When most of the CO₂ escapes and the drink goes “flat,” that carbonic acid level drops, so the soda tastes sweeter, duller, and less refreshing.

Why shaking and pouring change fizz

Shaking soda spreads CO₂ bubbles through the liquid and into the headspace, increasing internal pressure so that, when opened, foam and fizz can erupt dramatically. Pouring into a glass increases the exposed surface area and adds tons of new nucleation sites on the glass walls and in the liquid, which makes the soda fizz more as CO₂ escapes faster.

When soda goes flat

Once opened, the CO₂ slowly escapes until its concentration in the soda matches the air around it, leaving the drink flat and less lively. Colder, tightly sealed soda holds on to its fizz longer, while warmer, frequently opened bottles lose their bubbles and tang more quickly.

Information gathered from public forums or data available on the internet and portrayed here.