hi there I'm Jeremy Krug and in this video we're moving on with unit 4 section 2 as we continue to talk more about net ionic equations in our last video we learned about how to determine the solubility rules and to determine if something is soluble or not in solution in this video we're going to apply those rules so let's try an example here let's see what happens when Solutions of barium nitrate and sodium sulfate are mixed vigorously well the first thing that you want to do is isolate your reactants and write them in ionic form if possible so in this first one we have the barium nitrate and we know that nitrates are solubles we need to write that in its ion form so that would be barium two plus and nitrate ions now next we have sodium sulfate so that's also soluble and we know that because it says that there's a solution of that as well so is it soluble yes so we have to write these in its ion form so that would be sodium in a plus and sulfate is so4 to negative now once you write these reactants in ion form you need to realize that the ions are going to try to swap Partners so that means that this barium over here is going to try to pair up with the other negative ion and likewise this sodium is going to try to pair up with the other compounds negative ion they're going to try to swap out now we have to ask ourselves which of those combinations is going to produce an insoluble compound now in order to answer this we have to know our solubility rules and if you remember the solubility rules from last video you might remember hopefully that barium sulfate is the combination that's going to be insoluble so yes you need to know those solubility rules now these other ions that don't do anything we call those spectator ions because essentially well they're Spectators they're just sitting there they're not doing anything they aren't actually participating in the game as it were they aren't participating in the chemical reaction so what's going to happen is the barium two plus ions are going to react with the sulfate so42 negative ions and when they get together they're going to make barium sulfate and so this is how you would write the overall equation for this process now when you write this this is something called the net ionic equation and the net ionic equation essentially omits these spectator ions those ions that really aren't doing anything in the reaction let's try another example let's try a chemist takes a flask of potassium chloride and adds a few drops of silver nitrate solution so once again we start with the first one potassium chloride that's soluble so we have to write it in its ion form so that would be K plus and cl negative and then we have silver nitrate solution of course that's in solution so it's soluble so silver nitrate would be AG plus and then nitrate is NO3 negative and just like last time those ions are going to try to swap Partners the outsides are going to get together or try to get together in the insides we'll try to get together so once again we have to ask ourselves which of those combinations is going to produce an insoluble compound and once again you have to think back to your solubility rules ornate nitrates are soluble but silver chloride is not soluble is it so you have to know that this is the combination that's actually going to make the insoluble precipitate the product so that means that these other two your potassium ion and your nitrate ions those are called spectator ions aren't they so we have to take the AG Plus and a CL negative and those will combine to make agcl solid so that's how you'd write the net ionic equation for that process let's try another example Solutions of calcium nitrate and zinc chloride are mixed in a beaker once again the same process calcium nitrate well soluble all nitrates are soluble so that would be calcium ion ca2 plus and NO3 negative just like that and then we have zinc chloride once again that's soluble so it's zinc two plus and chloride negative and just like we did before these ions are going to try to swap out and we have to ask ourselves which of these is going to make the insoluble precipitate and you might be thinking well hang on here all nitrates are soluble so it's not that one and chlorides are soluble too aren't they and this is not an exception so it actually looks like none of these will make the insoluble precipitate and that's correct as it turns out there is no precipitate formed and all of these are actually spectator ions the calcium the nitrate the zinc and the chloride and so when that happens when the nothing's going to react well it's no reaction and that does happen sometimes where you add two solutions and you look in the beaker or look in the flask and nothing happens it's a no reaction now just so you know generally speaking on the AP Chemistry exam they're not going to give you too many of these no reactions there's going to be something that reacts for the most part but just be aware that in the real world in the laboratory yeah you can mix Solutions and nothing happens that is not unusual let's try another one Solutions of potassium phosphate and lead to nitrate are allowed to react in a test tube so same deal here we're going to take the potassium phosphate and that's a solution so it's K plus and phosphate is po4 three negative and we're going to add lead to nitrate to that so that would be PB two plus and then NO3 negative and the same thing the ions are going to swap out here here and we have to ask ourselves which of these two combinations is going to make the insoluble compound and hopefully you remember the rule from the last video that phosphates are generally insoluble aren't they so it's going to be the lead to phosphate and that means that your potassium and your nitrate those don't make a solid so those are going to be the spectator ions and so I'm going to write them over here just in their ion form and we're going to make this lead to phosphate so when you write the net ionic equation we have pb2 Plus po4 3 negative the phosphate will yield lead to phosphate so there's our knit ionic equation one little detail that you want to take care of though notice this is not a balanced equation you want to balance that equation so we have three lead atoms and and two phosphate ions on both sides of the arrow so that's generally speaking how we write net ionic equations now we could stop there and say that's it but the fact is there are a couple other things you need to know about there are some details there are a few compounds that sometimes you'll encounter in these equations in these products that don't actually exist there are three special cases where that's the case and these are substances that do not exist at normal temperatures and pressures they just really don't exist and so instead of being produced they're going to undergo what's called a gas Evolution reaction now the first one carbonic acid is one that we've talked about a little bit in unit three carbonic acid will basically spontaneously turn into water and carbon dioxide and so this is essentially carbonated water is what you have here now sulfurous acid h2so3 undergoes something similar except it's going to produce water and sulfur dioxide gas so that's the gas Evolution reaction for that one and ammonium hydroxide doesn't really exist either at normal temperatures and pressures it's going to do something similar except it's going to produce water and ammonia gas you need to know those three and what they produce let's try a couple of examples with these the first one is one that you've probably seen before solid baking soda sodium bicarbonate is poured into a beaker containing a solution of vinegar dilute acetic acid you may have done this reaction in elementary school and you've probably seen what happens when you mix baking soda and vinegar well let's take a look at this here so the solid baking soda is sodium bicarbonate now notice that this is not in solution so we don't ionize it ionic compounds are only ionized when they're dissolved in water so since this is not dissolved we just have to write it as nahco3 now the vinegar that acetic acid is a weak acid and you might remember from you know back in unit 3 weak acids are not ionized to any appreciable amount so we just write it as its formula H c2h3o2 and once again we're going to try the same thing we're going to try to swap these ions out here and think which of these two is going to make something well if you take the H and add it with hco3 you're going to have something you'll have H2 CO3 these others you know sodium and acetate and that's going to be soluble in that solution so those are going to be ionized now one thing that we hopefully remember is that h2co3 doesn't really exist in this reaction we should probably cross that out and replace it with water and carbon dioxide gas and if you look at this equation and the way it's written there really aren't any spectator ions everything is doing something and so we're going to write it pretty much like this the nahco3 solid which is the baking soda is going to react with the vinegar that's the H c2h3o2 aqueous and we're going to make liquid water and carbon dioxide gas you'll see that in the form of bubbles probably quite vigorously bubbling and then you'll have sodium ions aqueous and acetate ions aqueous as well so that's the equation for what's going on when you mix baking soda and vinegar let's try one more example here with a gas Evolution reaction and in this example we're going to take a few drops of sodium hydroxide solution and add it to a beaker containing aqueous ammonium chloride so we'll start with the sodium hydroxide up here and that's a strong base and it is certainly going to dissociate all the way so we have sodium ions and we have hydroxide ions and then ammonium chloride anything that starts with ammonium is of course going to be soluble isn't so we have nh4 plus and we have CL negative so once again we're trying to swap these ions and we should try to imagine what's actually going to make something here well it's not the sodium and chloride is it because that's soluble but ammonium and hydroxide tend to do something don't they we would think that they'd be ammonium hydroxide right of course sodium and chloride are spectator ions but we also know that ammonium hydroxide is not really going to exist is it in this equation it's going to be ammonia and water in H3 and H2O so we actually do have a couple spectator ions here we have the sodium and the chloride are The Spectator ions so what's left is going to be the nh4 plus which is our ammonium ion aqueous and our hydroxide ions aqueous will produce water in its liquid state and ammonia gas and H3 and so if you mix this you're probably going to smell that ammonia gas it's probably going to have a fairly strong odor to it which is another sign of a chemical reaction I hope you learned about how to write net ionic equations if you did please slam that thumbs up button and leave a comment down below if you'd like that really does help the algorithm I'm Jeremy Kroger I've been teaching apicometry for something like 24 years and I hope you are able to learn AP Chemistry with these videos join me in my next video and we're going to be learning about other types of reactions some of which are not in solution thanks for watching