Physical & Chemical Changes

by Jules Bruno
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So now we can talk about reversible and irreversible changes to matter. We're going to say here that a reversible change is a change that could be reversed to restore the original substance off a given compound. Now what it classified as a reversible change. We have phase changes. We have the dissolving of compounds and liquids and, of course, physical changes. If we take a look here at this example, we have carbon dioxide, which is CO two s. Here means it's in. It's solid form, it undergoes some process and now it's gas. G here means gas. What? It went through this process, but I didn't change the identity of the original substance. It's still carbon dioxide. It's just in its gashes form. So we're going from the solid form to the gashes form. Phase change, we said our common type off reversible change. And when we're talking about these reversible changes, that means we're going through the different phases of matter. Now when we're talking about bond forming reactions, that means that the molecules within our substance are coming closer together and forming connections. Typically, when we're talking about bond forming, we could talk about going from a gas to a liquid that would be called compensation. Remember, we talked about compensation of water vapor on windows. We could go from liquid to solid liquid to solid. We put water into a nice tray and put it in the freezer. And what happens to it? It freezes so liquid to solid is freezing. But we can also go straight from gas to solid. This is a term not all of us may know, but going from a gas toe a solid, you're depositing a solid. So this is called deposition? Yeah. Now the opposite side of that, If I can form bonds by going through the different phases of matter, then I should be able to break bonds by going through the different phases of matter. So if we're going from a solid to a liquid, we're going to be doing melting now in chemistry. Another name for melting is fusion. So we can say melting or fusion fusion is that's the fancy way of talking about it. Now. Fusion is an interesting word because it could mean different things, depending on what area and chemistry you're talking about when we're talking about the concept of melting we can use fusion, but fusion can also be involved with nuclear chemistry, nuclear chemistry. We're talking about fusion. We're talking about different types of elements, combining together to make a bigger element. But for right now, don't worry about nuclear chemistry because that's several chapters later. For now. When we say the term fusion, we're referring to it in terms of melting now you could also go from liquid to gas. If you're going from a liquid to a gas, that's evaporation or vaporization. So we're talking about vaporization here. Then we can also go straight from solid to gas. Solid to gas is called sublimation. So just remember, in a reversible change, we can go backwards and restore our original material. We haven't truly changed the identity of our substance. Common examples are face changes dissolving and, of course, our physical changes. Now that we looked at reversible changes, let's move on to irreversible changes