 So again, this is one of our qualitative tests to just identify the presence of particular functional groups. And in this case, it's the hydroxyl group or the OH group. Now we know that the OH group occurs in one of three places for different types of alcohols. For the primary alcohols, the OH group is on an end carbon. For secondary alcohols, there will be a couple of carbons and an OH group, which is sitting in the middle. And then for the tertiary alcohols, there will be a third carbon attached to those other two and the OH group coming there. Now I've simplified this by not adding any hydrogens or any additions. And that helps us to focus in a little bit on exactly what's going on. So because this is a qualitative test, we just need to identify the position of the hydroxyl group. So we need to know where it is. So the best way of doing that is to use something where we have a color change. That is, if a reaction occurs, we can actually see that that reaction has occurred by identifying a change in color. Two oxidizing agents are particularly good for this. They are the permanganate iron, which is a purple color and is the preferred iron. You can also use the dichromate iron, which is an orange iron. However, it's a little bit more dangerous to use. And so we tend not to use it as much. It is in your data table. So it in your table of standard reduction potentials. So it is certainly one that you can use theoretically. And the color changes that we would expect to see for a positive result are colorless. If we are using the permanganate irons from purple to colorless and orange to green, the chromate irons is going to be what you're going to find for the reduction of the dichromate iron. So both of these are oxidizing agents. They cause oxidation to occur in other species. The easiest one to start with, of course, is the tertiary alcohol because the tertiary alcohol will show no reaction. We will not get any reaction from our tertiary alcohol. So no matter what we do, we can warm it up. Nothing's going to happen. We will see no reaction. And that will tell us that this is a tertiary alcohol. If we have a primary or a secondary alcohol, then we will see a reaction. So there will be a reaction. So we'll go tick to color change. And tick to color change. In the laboratory, it's pretty difficult to stop primary alcohols from going right through to carboxylic acids. We can check and see whether or not they are acids by doing something very simple, such as identifying the pH of the solution. Many of these acids also have a particular aroma. So you can sometimes detect it from that as well. But a test for pH is sometimes the simplest one. You can also carry out a nice simple reaction such as the addition of a carbonate, for example. We now know that acids react with carbonate to produce carbon dioxide gas. And so therefore that will also help us identify our acids. Of course, the key functional group here is a carbon double bonded to an oxygen and then single bonded to another oxygen, which is also bonded to a hydrogen. So this is our carboxylic acid functional group. And it's what happens when we oxidize a primary alcohol. Now there may be an intermediate, so we may actually get our aldehyde or our alkanal, which is an intermediate between each of these two. If the reaction conditions are cool and we have some way of being able to slow the process down a little bit, maybe very dilute solutions, we may actually be able to stop at the aldehyde, but it's very difficult in the laboratory to actually do this. So usually we push the reaction right through and form the carboxylic acid. For a secondary alcohol, what we're going to produce is a ketone. So our hydroxyl group becomes a double bonded oxygen. Again, we have a tick for color change. And so we're going to have our new product, which is going to be the ketone or the alkanone of whatever the original secondary alcohol was. Now remember, what we're doing here is we're just doing qualitative tests. So we just wanna know what's present in each of these. The actual chemistry and being able to write the equations. And as we've looked at in other videos, being able to write the oxidation half equation and being able to identify the correct reduction half equation depending on which of the oxidizing agents you're using from the standard table of reduction potentials will give you a chance to write the full reaction occurring. It is important when you're discussing each of these processes to identify the reaction conditions. And it's important when you're carrying these out to recognize that we can use warm, cold, or hot solutions of the permanganate and the dichromate ions. And we can also make them either acidic or basic. And so some of the times you'll find that we've actually added hydrogen ions, for example, into our solutions to make them acidified solutions of permanganate or dichromate. The most common reaction conditions that we would have though, if we wanted to make sure we saw some very clear color changes is if we have a primary alcohol, we use warm to hot acidified permanganate. We're going to drive that primary alcohol all the way through to the acid. We do likewise for our secondary but that's going to stop at the ketone. So reacting with a carbonate ion or testing the pH will tell you the difference between those two even though the color change will look the same. And then obviously the tertiary alcohol won't react. So important that you see each of these reactions in the laboratory. And thanks for watching.