Is steam a mixture?
Steam is a compound, strangely enough.
In the article that follows, we’ll explain what steam is, and why it is (or is not) a mixture, compound, or pure substance.
First, What Is The Difference Between A Mixture, Compound, Or Pure Substance?
A mixture is a material that is made up of more than one kind of substance. The substances that make up a mixture can be elements, molecules, and/or compounds in any kind of combination.
The thing is with mixtures is that there needs to be at least two of the substances which are not bonded to each other. These substances can be separated, even if you have to go down to the molecular level to do it.
There’s no chemical bonds between them. Usually they retain their original physical characteristics but not always.
A compound is a material made up or more than one substance, where the substances are bonded together. The substances can be elements, molecules, or compounds.
These substances cannot be easily separated, and they generally lose their original physical characteristics when bonded together.
A pure substance can be a compound, but will never be a mixture.
A substance qualifies as a pure substance is it is made up of only one thing, with that thing being an element or a compound.
If the substance has more than one element or compound, then the substance cannot be considered a pure substance.
Next, What Is Steam, Exactly?
To classify steam as a mixture, compound, or pure substance, we have to first understand really well what steam is.
Liquid water is a compound, and it is formed when two hydrogen atoms bond with one oxygen atom.
When you heat liquid water, the substance evaporates, and turns into a gas.
When the water changes phase, the hydrogen and oxygen atoms remain bonded together as they were before as a liquid.
At the molecular level, gaseous water and liquid water are the same composition, though the molecules themselves behave differently at the different temperatues.
Is Steam A Compound?
Yes, steam is a compound.
The reason? Liquid is a compound.
And since there is no chemical or molecular make up difference between liquid water and gaseous water, steam is a compound.
Is Steam A Mixture?
In general, pure steam is not a mixture.
As discussed above, steam is water, but just in a different phase.
It is a compound, which is two or more different substances that are bonded together.
To be a mixture, a substance would need two or more different substances that are not bonded together.
Since the substances that make up each molecule of steam are bonded together, it cannot be a mixture.
That being said, we can imagine a situation where steam could be considered a mixture.
For example, let’s say the evaporated water (the steam) was mixed up with another gas, like the air.
If you took a sample of steam just straight out of the room you are in, over a boiling pot, odds are pretty good that you also captured some of the air from the room with it.
The air we breath is composed of several different gases: oxygen, hydrogen, and nitrogen, for example.
A sample of steam taken casually from your kitchen would be considered a mixture of the evaporated water and the various gases, as they would not be bonded to each other.
If you are answering this question on a test, make sure you are clear that you are speaking of “pure steam” (aka pure water) or the air/steam mixture you’d otherwise casually collect.
Is Steam A Pure Substance?
This depends upon whether the steam is purely “steam” or is mixed with something else.
As we discussed above, steam is water, just in a different phase (gaseous vs liquid).
And remember back to what a pure substance is: a material made up of one kind of element or compound.
Water is a compound.
Thus, steam technically should be considered a pure substance (like water is a pure substance), as it is made up of only one kind of compound (water).
However, in reality, steam is rarely found without being mixed with the air. It is certainly possible to have steam without air mixed in.
But most samples that we’d collect would have the evaporated molecules mixed in with the steam.
Thus, steam can be a pure substances, but only if the steam is pure.
If the steam is not pure, then the sample mixed with the air could not be considered a pure substance.
Is Steam An Element?
No, steam is not considered an element.
An element is a substance that cannot be broken apart or broken down into other substances.
Gold is a good example of an element, as it cannot be broken apart into other substances.
Steam is evaporated water molecules.
Water is a compound, made up of hydrogen and oxygen bonded to each other.
The hydrogens and oxygens can be broken apart into their separate forms.
Because water (aka steam) can be broken apart into oxygen and hydrogen, it cannot be considered an element.
Interested in learning more about pure substances and mixtures? Or whether materials like paper, bronze, copper, milk, vinegar, blood, glass, baking powder, and honey are considered pure substances or mixtures?
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