Here are some of them:. Mixtures A mixture is made from different substances that are not chemically joined. Mixtures and compounds Mixtures have different properties from compounds. Mixture Compound Composition Variable composition — you can vary the amount of each substance in a mixture Definite composition — you cannot vary the amount of each element in a compound Joined or not The different substances are not chemically joined together The different elements are chemically joined together Properties Each substance in the mixture keeps its own properties The compound has properties which are different from the elements it contains Separation Each substance is easily separated from the mixture It can only be separated into its elements using chemical reactions Examples Air, sea water, most rocks Water, carbon dioxide, magnesium oxide, sodium chloride An example - iron, sulfur and iron sulfide Iron and sulfur react together when they are heated to make a compound called iron sulfide.
Here are some of them: the mixture can contain more or less iron, but iron sulfide always contains equal amounts of iron and sulfur the iron and sulfur atoms are not joined together in the mixture, but they are joined together in iron sulfide the iron and sulfur still behave like iron and sulfur in the mixture, but iron sulfide has different properties from both iron and sulfur you can separate the iron from the mixture using a magnet, but this does not work for iron sulfide.
Variable composition — you can vary the amount of each substance in a mixture. Definite composition — you cannot vary the amount of each element in a compound. The different substances are not chemically joined together.
Now, you can imagine if there's heterogeneous mixtures, the opposite would be homogeneous mixtures. Those would be mixtures that when you look at it from a macro point of view, it looks consistent any point of the mixture.
Homogeneous mixtures. And homogeneous mixtures, there's another term for it, which you have probably heard. They're also known as solutions. And as I mentioned, when we talk about mixtures, we could be talking about solid, liquid or gas. Oftentimes in our head, we think liquid immediately, but it can be solid liquid or gas. And so the same thing is true for solutions. You can have solid liquids or gases. And an example of a solid solution would be, say a metal alloy.
Where at the macro level it's color, how well does it conduct electricity? How malleable is it? How hard is it? It looks like the properties are uniform throughout the alloy.
If I have some type of metal alloy, if I were to just look at it like this, if I were to look at say bronze, well, from my point of view, it has the same properties throughout the bronze. And I should probably do bronze in a more bronze color right over here.
But if you were to look at it with a very sensitive microscope or based on the models that we now know what is going on in that metal, in that alloy, what's happening is you actually have a mixture of metals. But it is a homogeneous mixture of metals because at a macro level, you can't really see the differences.
Now at a micro level, you can, because there are different metals mixed in together in this alloy. Now, as can imagine you also have liquid solutions and in chemistry, these are the ones that we'll often deal most. We will also deal with solid and gas solutions as well.
And when I think of a homogeneous liquid mixture or a liquid solution, the one that comes to mind for me, but we'll see a lot of these in our journey through chemistry is salt water. Salt water. Salt water has sodium chloride dissolved in water. Often separating the components of a homogeneous mixture is more challenging than separating the components of a heterogeneous mixture. Distinguishing between homogeneous and heterogeneous mixtures is a matter of the scale of sampling.
On a small enough scale, any mixture can be said to be heterogeneous, because a sample could be as small as a single molecule. In practical terms, if the property of interest is the same regardless of how much of the mixture is taken, the mixture is homogeneous.
Some mixtures can be separated into their components by physical mechanical or thermal means. Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Introduction to Chemistry. Search for:. Substances and Mixtures. Learning Objective Distinguish chemical substances from mixtures. Key Points Matter can be broken down into two categories: pure substances and mixtures.
Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule.
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