In this video, we're going to take a look at the different tasks that we can use in order to identify the different types of anions within our chemical solution. So anytime we have a reaction occurring, remember that a reaction only occurs if we produce a solid, liquid or a gas as a product. Now based on these phases being formed, ions will also exist within the solution. So you'll make one of these forms or maybe more than one of these forms, solids, liquids or gases, and you'll have ions floating around as well. Now we can identify these different ions through a series of tests.
For right now, we'll take a look at the anions and later on we'll take a look at the cat ions. So we're going to need room guys. So let me take myself out of the image. So for the first three ions, we're dealing with chloride ions, bromide ion and iodide ion. They're all in Group 7 A, so remember these are all our halogens. We're not talking about fluoride ion F minus because of certain properties. It's too dangerous to talk about in terms of these reactions, so we tend not to discuss it in terms of identifying it. All right? So we're going to say for our chloride ions, bromide ions and iodide ions, they're all basically the same thing. To a solution, we add nitric acid and then we followed up with silver nitrate.
Now what's going to happen in each case? Is that the silver we'll combine with the halogen? OK, so here since all of them have the same exact number in terms of their charges, they're just going to cancel one another out and and then the elements combined. So we're going to get silver chloride here, we're going to get silver bromide and silver iodide. Here's the thing. Each one of these compounds is a solid. So by adding these ingredients or reagents HNL three to each one of these ions, we're going to form these different solids or precipitates. OK, so a solid is equal to a precipitate. Now if you don't know what I'm talking about, make sure you go back and take a look on my videos dealing with solution chemistry. When we talk about the solubility rules, when we talk about ions and electrolytes, when we talk about molecular equations, net ionic equations, and total ionic equations, this those concepts are being brought here right now in order to talk about tests we can run to figure out which ions we have.
Now here's the thing, all of them, when we add nitric acid and silver nitrate produce all these solids. So how do we know which ion we have? In particular, while each one of these solids has a distinct color to them, silver chloride will be seen as a white precipitate, OK and that white precipitate will thicken overtime. So thinking overtime, so what's going to happen here is it's going to get cloudy within the beaker. OK, so let's say you or a test tube, let's say we have a test tube here. You're going to have your white precipitate down here. I know it's black, but we need, oh, it's going to be a white precipitate. And the solution itself is going to get cloudy over time. That's what I mean by thickening. Silver bromide, silver bromide. It's going to be close to white precipitate like silver chloride, but it's going to be more of a creamy white precipitate. It's going to look slightly different. So silver chloride is a pale white. Silver bromine is a creamy white and then silver iodide. We're going to get a yellow precipitate. All of these will cause the solution to get cloudier because of the formation of that precipitate.
So that's how we're able to differentiate which one of these ions we have. So if you have an unknown solution and you're trying to investigate which one of these three ions you have and all of them you add nitric acid followed by silver nitrate and then you look to see what is the color of the precipitate that form match the color with the ion. If no precipitate forms, that means we don't have chloride ion, bromide ion or iodide ion. Next we're trying to investigate if we have carbonate ion or we have bicarbonate ion. So carbonate is this CO3^-2 and bicarbonate is this HCO3^-. Now bicarbonate is also called hydrogen carbonate as well as as well as bicarbonate. So what's going to happen here is to these things we add hydrochloric acid, HCL. Now what is going on reaction wise? So here we have carbonate and we add HCL to it. Now HCL is made-up of H plus and CL minus. What's happening here is the positive H here is going to combine with the carbonate here, and because their numbers are different, they're going to Criss cross. Two goes there and one comes here to give us H2CO3. This is carbonic acid, which is not stable, so when it forms in solution it doesn't stay that way. It quickly decomposes, which means it breaks down to produce water as a liquid plus CO2 gas.
South here, we're going to get the formation of carbon dioxide gas. OK. So what we're going to say here is we're going to get basically CO2 gas bubbles out of the solution. And I'm going to say CO2 is colorless, has no color to it, OK. And we're gonna say here, when it does this, it could change. This is going to change the water to cloudy white. Now the same thing can be done if we used bicarbonate because it would also combine with the H plus from the HCL. But here, since their numbers are the same, they just cancel out and combine together and again you'd make carbonic acid, which again would produce water and CO2. So both of these things, if we had HCL will produce carbon dioxide as a gas, indicating that they're present. But how would I be able to tell if I have carbonate instead of bicarbonate? What additional thing could I do? Well, what I could do here additionally? Additionally, I could add, if we add magnesium sulfate, that will help me determine if I have carbonate or bicarbonate for sure. So if I add magnesium sulfate, what it's going to do here? It's going to form a white precipitate if carbonate is present, and then here if bicarbonate is present, we will have no precipitate form. So that's how we're able to differentiate the two.
So again, adding HCL to both will produce CL2 gas. But if we want to be sure if we have one instead of another, we do an additional step, we add magnesium sulfate. If carbonate is present, we form a right white precipitate. If no carbonate is present, we get no precipitate. Next we have sulfate and bisulfate or what's called hydrogen sulfate. So for this one we can add HCL and then we follow it up with barium chloride. And what happens here is if we have the barium chloride, the bearing is going to connect connect with the sulfate to give me barium sulfate, which will be a solid. The same thing would happen whether I used buy sulfate or just regular sulfate. They both will produce this, which would be a white precipitate. But what if I wanted to make sure I had one ion instead of another? What could I do? Well to differentiate between sulfate and bisulfate, what I could do is I could add sodium carbonate. Now here if I add, actually we don't even need to do this yet, but we could do. Instead of that, we can heat the solid. So we heat the barium sulfate that we have, OK? And we're going to say here, if we get SO3 gas is produced with light heating, then that means that we had our bisulfate. But if you get SL3 gas with only strong heating, that means we used sulfate. OK, so that's how we're able to differentiate which one of these ions is truly present now here, like I said.
So that's one thing we could do. Another thing that we could do to differentiate between the two is we could add sodium carbonate. Now if we add sodium carbonate, we're going to say if a lot of CO2 gas is evolved, meaning released, then bisulfate is present. OK, so if you're releasing a lot of gas, buy sulfate is present. If little to no CO2 is present, then that means that we used sulfate. So again, these are important to know just in case you have a lab practicum or you have an experiment that's going on when they're asking you to identify different types of anions. These are the most common types of anions and the tests that we can use to figure them out. Next we have our sulfite ion. So to this sulfide ion we add hydrochloric acid. So we add HCL and we're going to say here when we add that HCL, so we're going to have SO3^-2 and then we have HCL which is made-up of H plus and CL minus. So the H plus and the SL3 to minus are going to react. So the two from here comes here and the one from here comes here. And what do we get? We get sulfurous acid. Now sulfurous acid is similar to carbonic acid that we saw earlier. This will undergo decomposition as well to produce liquid as water plus SO2 gas, sulfur dioxide gas.
So here we'll have the evolution or evolving of SO2 gas, which indicates that we have sulfite ion present. And one way you can tell that you have so two present is it'll be a strong smell, not a pleasant smell either. So you'll smell that. So two being produced and it smells really bad. So that indicates that our sulfide ion was present. Now finally we have our nitrate ion and L3 minus. So to this we can add cold iron to sulfate. And then we follow and then we follow up with some sulfuric acid. Now we're going to say that this is called the brown ring test. So basically from the name, you're going to form a brown ring within the test tube. So this lets us know that we have the presence of nitrate ion within this solution. So again, anions are our negative ions. These are the most common ones that we fall into contact with when we do a lab experiment. And these are just some of the tests that we can run in order to identify them. Some of them have common tests. So you have to look at the precipitate that forms, what color is it to help us differentiate the different types of halid anions that we have. And then for other ones, we have to do an additional step in order to differentiate if it's one ion versus another. So we've covered the anion portion here. We're going to take a look at the cation portions later on.
