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In the mid-1700s, a Unitarian minister called Joseph Priestly became fascinated by science. The brewery next to his home in Leeds, England, made Priestly curious about what makes beer bubbly–and that’s what led Joseph Priestly to invent soda. Today, soda is so common that we might never stop to wonder exactly what it is.
Soda is a solution of carbon dioxide gas dissolved in water. When something dissolves, it gets spread out evenly. This even distribution of ingredients is what makes soda a solution. But soda is also a mixture because solutions are a type of mixture.
Keep reading to find out more about solutions, mixtures, and the science of soda. Learn how Priestly made the world’s first fizzy water and how his original process has been modified over time. And finally, discover how you can experiment with soda yourself, at home.
Soda Is Both a Solution and a Mixture
A “mixture” is when at least two substances are put together without being chemically combined. Key characteristics of mixtures are that the substances inside them
- Can be combined in varying amounts
- Stay the same individual substances
- Can be mechanically separated.
Mixtures can be liquids, solids, and gasses. In the table below, you can see some examples of how one substance–carbon dioxide–can be added to other substances to form mixtures.
|Mixture||Not a Mixture|
|Carbon dioxide and water||x|
|Carbon dioxide and oxygen||x|
Carbon dioxide can be combined with oxygen in any amount you choose. Because the carbon dioxide doesn’t combine chemically with the oxygen, you can separate it back out, and it will be unchanged. But carbon dioxide itself is a compound, not a mixture. Carbon and oxygen need to combine in an exact ratio chemically to make it. Once they are combined, you can’t easily separate them.
Soda is a mixture because the water and carbon dioxide–as well as any flavoring or coloring that’s added–can be put together in varying amounts. Even though it looks like it’s all one substance, it’s really not. Everybody has experienced a “flat” soda. Sodas can lose their bubbles over time as the carbon dioxide gas escapes the liquid.
Soda is a particular kind of mixture called a solution. In a solution, a solvent is used to dissolve one or more substances–the “solutes.” In soda, the solvent is water, and the solutes are carbon dioxide and sometimes other ingredients. The substances in the solution form a homogeneous mixture–one where all of the parts are distributed equally. Because the solute has dissolved inside the solvent, the solute stays distributed and doesn’t settle out over time.
Carbon dioxide all by itself doesn’t meet these criteria, so it isn’t a solution. Carbon dioxide and oxygen, by themselves, aren’t a solution. But when they are dissolved in a large amount of nitrogen, the result is the solution that you’re breathing right now–air.
|Solution||Not a Solution|
|Carbon dioxide and water||x|
|Carbon dioxide and oxygen||x|
For more information about mixtures and solutions, you can watch this video:
How Soda Is Made
When Joseph Priestly discovered that the fizz in beer comes from dissolved carbon dioxide, he used this knowledge to also create bubbles in the water. He created carbon dioxide by combining chalk with sulphuric acid and trapping the gas in a homemade contraption made from a pig’s bladder. He then dissolved this trapped gas in water, and soda was born.
Unfortunately, contact with a pig’s bladder gave the carbon dioxide a nasty taste. A Scottish doctor, John Nooth, figured out a better way to trap the carbon dioxide–in a glass. Jacob Schweppe, a Swiss watchmaker, developed the first system for creating carbonated water that was efficient enough for commercial applications. This was the beginning of soda as a popular drink.
At first, any flavorings were mixed with soda water either at home or in shops where soda was sold. Today, of course, flavored soda is mostly made in factories. Water makes up 90-99 percent of the average soda, so the process of filtering the water–usually through layers of sand–is very important. Any impurities in the water can negatively impact the taste of the soda. Carbonation from various industrial sources is then introduced. Because carbon dioxide can easily escape the solution, different manufacturers use different processes to create the perfect fizz and flavor.
To see an old-fashioned soda delivery company in action, watch this video:
And if you’re curious about how soda is made in commercial factories, you can have a look here:
Soda Science at Home
If learning about the science and history of the delicious solution we call soda has inspired you, maybe you’ll be interested in some soda science you can do at home.
Make Your Own Soda
The process of creating and trapping carbon dioxide isn’t simple and probably not something to try at home. But you can buy a variety of products that have already taken care of this process for you:
- Zipfizz Healthy Energy Drink Mix: This comes as a powder, but when you dissolve it in water, it becomes a carbonated energy drink full of vitamins and electrolytes.
- Baskiss Soda Siphon Maker: You can use Liss 8 Gram CO2 Cartridges to charge this soda siphon–then just add water to make your own soda. It’s an easy way to make bubbly water over and over.
If you want to flavor your soda, there are many options to choose from.
- Torani Syrup Variety Pack, Soda Flavors contains a variety of Torani’s famous fruit flavors.
- Get extra fancy and try Monin Lavender Syrup or Monin Exotic Citrus Syrup.
Maybe you’ll discover that you really love your homemade creations–and if you decide you want to make them regularly, you may want to check out these options:
- SodaStream Fizzi Sparkling Water Maker Bundle–it’s got everything you need to make your delicious bubbly drinks. It comes with cartridges, flavoring drops, and even bottles to hold the soda.
- Make Your Own Soda: Syrup Recipes for All-Natural Pop, Floats, Cocktails, and More: this book is full of great recipes if you’re looking to really up your soda game.
Experiment with Soda
When you harness the pressure that carbon dioxide creates when it escapes the soda solution, you can create some interesting effects.
- You can use soda as the leavening agent in some baked goods. You need to work quickly if you want to try it, though, because you don’t want the carbon dioxide to have completely escaped before you put your sweet treat in the oven.
- What’s more fun than experimenting with cake? Check out this video to find out:
Soda is a solution and a mixture because it consists of carbon dioxide heterogeneously dissolved in water. It was invented in the mid-1700s by Joseph Priestly. Both John Nooth and Jacob Schweppe made important contributions to making this solution commercially available.
Today, the soda industry is huge, and soda is mixed in large factories. It is possible to mix soda at home, though, and there are several products that you can buy to help you with this process.
Any mixture or solution can be taken apart into the substances used to make it–and when we do this with soda by letting the carbon dioxide escape, we can harness the escaping gas to create interesting effects.