Look back to literally anywhere in time where there are humans, and you’ll find fire. Fire has been an integral part of our society for ages, and thus it only makes sense that we’re able to understand what it is.
However, in a discussion — or argument, depending on how you phrase it — I got into with a friend the other day was asking what state of matter fire is. There are four fundamental properties:
- Gas
- Liquid
- Solid
- …and plasma
It’s not a solid, so we can rule that out right off the bat, but it’s not really a liquid. Would we consider fire a gas? Not exactly. Probably not plasma, either. That’s when it comes to asking where we officially classify fire.
The first thing to do to officially break this down is to figure out what the major properties are of each of the states, and looking at which of those properties fire is able to qualify as. By doing this, we’ll be able to get a basic idea of where fire would make sense.
Well, let’s start by comparing fire to a gas. Most gases have no fixed shape or volume. Fire doesn’t really have a shape, and the volume expands or contracts depending on what you add to it (in this case, oxygen). So it’s a gas, right? Not quite — if you put fire in a container, it’s not going to expand and fill the container in the same way as any other gas. This disqualifies it from constituting as a gas.
Next, we’ll check out a solid. That would mean it has a fixed shape, nice and stable. The biggest issue here is fire not having this main, integral property. If you try and pick it up, it will burn through your hand (likely), rather than keeping the same shape you found it in. It moves if you blow on it. Fire isn’t a solid, either.
Up next: a liquid. Liquids don’t have to conform to a particular shape — meaning it’s looking good for fire — but they also do have a fixed volume, something the fire undoubtedly lacks. So it isn’t really a liquid either.
