Science Puzzle
Why Does Warm Lemonade Go Flat Faster?
Open a bottle of lemonade straight from the fridge and it stays fizzy for ages. Open one that's been left in a hot car or in the sun and it froths up and then goes flat much more quickly.
Why does warmth make a fizzy drink lose its fizz?
The Answer
Gases dissolve better in cold liquids than warm ones. A warm drink simply can't keep as much carbon dioxide dissolved.
The fizz is carbon dioxide gas, forced into the drink under pressure at the factory and sealed in. While the bottle is closed, the gas has nowhere to go. Open it and the pressure drops, so the gas starts to escape as bubbles.
How fast it escapes depends on temperature. In warm liquid the molecules move faster, and dissolved gas molecules escape more easily. Ice-cold water can hold about twice as much carbon dioxide as water at room temperature. So a warm drink fizzes up violently the moment it's opened, often spraying out over the top, and then quickly runs out of fizz. That's why fizzy drinks are best kept cold and closed.
The same rule matters far beyond the kitchen. Warm water holds less oxygen than cold water, which is why fish can struggle in rivers during a heatwave. And as the oceans warm, they can absorb less of the carbon dioxide that people release into the air.
The principle: Solubility of gases. Gases dissolve better in a liquid at lower temperatures and higher pressures, so warming a fizzy drink or opening it drives the gas out.