We all know from childhood that if you shake a bottle of soda before opening it, a powerful foamy “fountain” is guaranteed. It would seem that there is no secret in this – after shaking, the pressure in the bottle increases, as a result of which, when opened, the contents burst out under pressure. However, there is one nuance – a bottle of soda is a closed system. This means that to increase the pressure in it, you need to squeeze the bottle or pump something into it. Therefore, if you attach a pressure gauge to the lid, you will find that after shaking, the pressure does not increase. But what is really happening?
Shake the soda vigorously and open the lid, and you're guaranteed to get a fountain of foam. Photo source: ecestaticos.com
Contents
- 1 How carbonated drinks are made
- 2 Why bubbles appear and fizz when you open the soda
- 3 Why soda should be poured along the edge of the glass so that it doesn't foam
- 4 Why does soda “explode” after shaking?
How carbonated drinks are made
The fizz and pleasant tingling sensation in the mouth that we love so much about carbonated drinks is created by carbon dioxide (CO2) dissolved in the liquid. This is the same gas that you and I exhale, and which, according to some scientists, causes global warming.
It must be said that soda owes its appearance to beer, which people have valued for thousands of years for its subtle, bright taste and unique sensations in the mouth. And beer owes all this largely to bubbles. However, in this drink, carbon dioxide occurs naturally thanks to brewer's yeast.
Long before soda appeared, people noticed that bubbles give beer a more subtle and vibrant taste. Photo source: ultraimagehub.com
In 1767, a British chemist, Joseph Priestley, who worked as an ordinary brewer, decided to make other drinks carbonated like beer. He worked on his idea for a long time, and eventually created a device called a saturator. Such devices are used to create carbonated drinks to this day.
The principle of the saturator is quite simple – to saturate the drink with carbon dioxide, that is, to dissolve the gas in the liquid, CO2 is supplied to the bottle under pressure, which is much higher than atmospheric. To prevent this gas from escaping, the bottle is tightly closed with a lid, ensuring complete hermeticity of the container. As a result, even ordinary water becomes much tastier. However, you should not abuse carbonated water, as this can lead to health problems. And even more so, you should not often drink sweet carbonated drinks, which are even more dangerous to health. A striking example of this is the population of Mexico, where people drink Coca-Cola instead of water.
Why does soda bubble and fizz when you open it?
The gas in the bottle outside the liquid and the carbon dioxide dissolved in the drink reach chemical equilibrium. This term means that the rate at which carbon dioxide leaves the liquid is equal to the rate at which the same gas dissolves in it. When the lid is opened, the pressure in the bottle drops, which disrupts the chemical equilibrium. For this reason, the carbon dioxide dissolved in the liquid (H₂CO₃) is converted back to CO₂, i.e. it leaves the liquid.
The larger the surface area of the soda, the more intensively it releases carbon dioxide. Photo source: techinsider.ru
For this reason, bubbles filled with gas appear in the liquid, which are pushed out into the surrounding space. This process is accompanied by a characteristic hissing and foam formation. Moreover, the more the drink is prone to foaming, the more foam appears on its surface.
Why soda should be poured along the edge of the glass so that it does not foam
To make the glass less foamy and have more of the drink itself, it is poured carefully along the wall of the glass. And it doesn't matter what kind of drink it is – kvass, beer, champagne (another carbonated drink that appeared long before soda), etc. For example, for this reason, bartenders hold the glass at a certain angle when pouring beer. But how does it work?
Carbonated drinks should be poured along the edge of the glass to avoid foaming. Photo source: click-or-die.ru
The whole secret is that the rate at which carbon dioxide escapes from a liquid depends on its surface area, significantly increasing the surface area compared to when you slowly pour it along the walls.
For the same reason, the wider the glass or goblet, the faster the liquid in it becomes still. That's why glasses, for example, for champagne, are made narrow and tall.
When you shake soda, the pressure inside the bottle doesn't increase. Photo source: vk.com
Why does soda “explode” after shaking?
After shaking a bottle of soda, carbon dioxide actively begins to be released from it, but what is the reason for this? When shaking, we force the gas that is above the liquid to actively mix with it. However, as mentioned above, the contents of the bottle are in a state of chemical equilibrium. That is, the liquid cannot dissolve more carbon dioxide than is in it.
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For this reason, excess gas forms bubbles throughout the bottle. But what is a single bubble in water? This is an additional surface area of the water. Since many such bubbles appear in the liquid, its surface area increases greatly. Each bubble begins to expand, and the surface area of the liquid expands even more. As a result, when we open the bottle, the bubbles push the liquid out of it.