What’s the Matter?
Baking a cake was never so educational – or so fun! Come into the kitchen with Ask Science and learn about the four fundamental states of matter.
Lee Falin, PhD
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What’s the Matter?
Many of us grew up hearing about the 3 states of matter: solid, liquid, and gas. You might be surprised to learn that there are actually quite a few more than 3 states of matter. We might try to excuse ourselves from knowing about these other states of matter because they must be very uncommon, right? Unfortunately, one of these lesser-known states of matter isn’t uncommon at all. Plasma is considered the fourth, fundamental state of matter and is actually the most common state of matter in the universe. Go figure!
Let’s take a look at how we interact with these different phases of matter when we bake a cake. So grab your favorite cake recipe and follow me to the kitchen.
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Solids
It’s pretty easy to identify the solids in our cake baking exercise. In solid matter, the molecules that make up a substance are packed together very tightly. One of the effects of this is that solids typically have a definite shape that resists being changed.
As we reach for our mixing bowl, hand mixer, measuring spoons, and chef’s hat, everything we’ve gathered together is a solid.
Liquids
The molecules of a liquid are packed together less tightly than that of a solid, which allows them to slide around quite a bit. This means that a liquid can change its shape to fit its container. However the overall volume (or total space the liquid takes up) generally doesn’t change, as long as the temperature and pressure stay the same.
Liquids are also pretty easy to identify, milk and water for example are obviously liquids we’ll need for baking our cake.
Gas
Unlike solids and liquids, matter that is in the gas state typically doesn’t retain its state. The molecules of a gas aren’t packed tightly together at all and tend to float around wherever they want, completely independently from one another.
If you have a gas-powered oven, then when you turn your oven on to bake the cake, a flammable gas (either propane or methane) is piped into your oven to provide fuel for the fire. If you have an electric oven, take comfort in the fact that the reason mixing baking soda and the milk allows your cake to rise, is because acids and bases produce carbon dioxide, which in this case is in a gas state.
Plasma
What about this mysterious plasma I mentioned at the beginning? Well like gasses, the molecules of plasma are not packed together tightly. One of the main differences between plasma and gasses is that plasmas can conduct electricity and can be strongly affected by electromagnetic fields.
See also: Why Doesn’t Static Electricity Kill You?
You might be surprised to learn that plasma was one of the first states of matter you probably interacted with during your cake baking, by simply turning on the light switch. Fluorescent lights are filled with special gasses that become plasmas when hit with a strong enough burst of electricity.
Misfits of Matter
As you glance around the kitchen, waiting for your cake to finish cooking, you’re feeling a bit smug about your new understanding of the states of matter. But then your eyes fall on the eggs and you face a moment of doubt. Are eggs liquids or solids? What about the whipped cream you were going to put on top of the cake? Is it a solid, liquid, or gas?
Many substances consist of more than one state of matter mixed together. When this mixing is done on the microscopic scale, its known as a colloid. For example, egg whites are solids mixed into a liquid, a type of colloid called a gel. Other gels you might find in the kitchen include jelly and gelatin.
Whipped cream is not only a delicious topping for any cake, but it is also a type of colloid known as a foam, which is a gas mixed in with a liquid.
Conclusion
So now, not only do you (hopefully) have a delicious cake in your oven, but you also know about the states of matter that went into preparing it. Just keep in mind that matter can change between its various states. So just because your water is a liquid right now, doesn’t mean it was always – or will always be – that way (just think about those delicious popsicles we eat in summer). Matter can transition between the 4 fundamental states through various means, which we’ll discuss in a future episode.
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Milk, gas oven and brown eggs images from Shutterstock
