all right I promised you with a buildup to things so let's get things started let's light the lights and let's make the final step H happen for Ionic equations tonight what is an ionic equation and what does it have to do with our precipitation reactions ionic equations display how things actually exist rather than write them in a way that's nice and neat um ionic equations display how the compounds atoms and ions exist in reality the big thing is an ionic equation displays soluble ionic compounds and strong acids as ions in an ionic comp in an ionic equation soluble ionic compounds and strong acids will be written as ions I capitalize strong acids for a reason and soluble should be capitalized as well because if it's not a soluble ionic compound or a strong acid then we're going to write the compounds the way they normally would how we normally write equations how we're used to seeing equations that actually has a name to it those are referred to as molecular equations a molecular equations how we normally write things and all compounds are written as compounds let's take a look at the molecular equation for the reaction of silver nitrate and potassium chloride this is the molecular equation when we write the ionic equation we're going to split apart any ionic compound that's aquous remember when we talked about electrolytes we said that ionic compounds split up into ions when they're in water so if we were to look inside a glass of water we wouldn't really see silver nitrate right what we'd actually see would we we would see the silver ion floating around and we would see the nitrate ion floating around because in an ionic compound an ionic compound that's soluble in water breaks up into its ions same for our potassium chloride we wouldn't see pottassium chloride together as a unit if it's dissolved in water instead and this little squibble here is AQ right in parenthesis what we'd see instead would we would see the chloride ion and the nitrate ion we'd see the potassium ion and the chloride ion separated let me clean things up here a little bit for you so that's what we'd actually have on the reactant side physically if we looked inside our water we'd have a bunch of silver ions floating around a bunch of nitrate ions floating around a bunch of pottassium ions floating around and a bunch of chloride ions floating around not these units together on the product side however silver and chloride have found true love right they've formed a precipitate they are more attracted to each other than they are to water molecules so they're going to come out of solution and because they come out of solution and they formed a solid they actually exist as a solid they actually exist as a unit of silver and chloride so when I'm writing this ionic compound that shows how things physically exist I'm going to keep them together as a unit my potassium nitrate however uh that's not the case right potassium nitrate are aquous and we know from our electrolyte lecture if it's aquous it's broken up if it's I aquous and I it breaks up so our potassium and our nitrate ions would be written separately what I have written for you right here this long drawn out thing is known as an ionic equation couple important things to keep in mind when we're dealing with ionic equations phases are important because phases determine whether or not something's broken up or together I will take off points if phases are absent or they're wrong right I went to all the effort to make my little AQ squibble there there in parentheses next to everything if phases are missing your equation is wrong the other thing is it's an ionic equation don't forget to write your charges if your charges are missing on your ions then the equation's wrong right I can't just write silver I have to write silver plus one I can't write just potassium I have to write potassium plus one I can't just write chlorine I have to write chlorine negative 1 who shouldn't have charges showing my compounds together here right so it doesn't have any charges showing you have to be careful these are the sorts of questions where I always recommend that you double or triple check your answers on exams because it's really easy just out of sheer absent-mindedness to forget a phase or to forget a charge writing an ionic equation is really pretty easy all you're going to do is you're going to break your ionic compounds up into their ions and then you're going to balance the place where people run into problems with ionic equations is they want to invent ions remember your nomenclature rules if you can't name it you can't write it for example let's take a look at this this equation here where we have strontium chloride aquous reacting with potassium sulfate aquous our first step is to break our aquous ionic compounds up I have strontium chloride right here strontium is a group 2A element so I know it's it's going to be 2+ then I have chloride have you ever memorized a CL sub 2 ion no so don't invent one it's a plus sign right there so your Ion is going to be chloride group 7 a so it's NE 1 then we come to potassium sulfate potassium is Group 1 a again have we ever memorized something K sub 2 no so don't invent a polyatomic ion when you haven't memorized one so that's potassium plus one then you should have memorized and should recognize that s so4 is sulfate now the other side of the arrow here I wrote way too large hard not to do quite frankly with the stylus we have strontium sulfate solid if it's a solid that means that the attraction the ions have for each other is greater than our attraction for water they love each other and no water molecule in the world can pull them apart so they're a solid and they stay together because they physically exist together potassium and chloride however they have no love for each other so they're broken up they've broken up just did something weird um and I meant that on the computer there all right potassium and then it's chloride so it's ne1 now balance I have one strontium one stomium I have two Chlor chlorines up here so I'm going to have two chlorides in my equation I have two potassiums so I'm going to have two potassiums in my equation down here right I'm taking care of those subscripts now with a balancing step not by inventing new ions once sulfate one sulfate one strontium one strontium I have two potassiums over here and two chlorides over here so I have to add two potassiums here and two chlorides there and that's it as long as you remember your nomenclature rules writing ionic equations is easy they're so easy in fact that um Kermit could handle them with no problem he would find them much easier than being green everybody write down Kermit k e r m i t Kermit after you write down Kermit I would strongly urge you to pause the Rea pause the reaction pause the lecture and try this on your own here apparently I need lunch pause the reaction and try this on your own did you pause me please please tell me you pause me I know I've been going on for a while now but I really want you guys to try this on your own look me in the eye that's right screen to eyeball here and tell me that you paus this all right let's check first step break things up that are aquous so I've got lead 2 nitrate so I have lead two I know it's lead two because of my nomenclature rules right I've memorized that I have nitrate at1 and I know I have two of them so my lead would have to be whoa threes are just impossible to write with a stylus all right there we go then I've got pottassium again and I've got bromide now on the product side lead two bromides are solid so it stays together solids Stay Together remember they're they're they've Fallen they found true love they're not going to be torn apart by the water molecule and and we've got our pottassium and I'm just out of room and our nitrate now we balance I've got one lead but I have two nitrates so I'm going to have to add two nitrates here two potassiums two bromides two potassiums two nitrates and I have to say it chemistry is easy life is hard let's take a closer look at this reaction okay same reaction right here the reaction we just solved for and here's our ionic equation right if you couldn't read my chicken scratch here it is nice neat and typed out didn't know I could do that huh if you look at this reaction there's something that leaps out at you why does it leap out at you because I put it in a different color than the others um you'll see that you have both pottassium and nitrate occurring on both sides of the equation in the exact same fashion right I have two potassium ions here and I have two potassium ions here no change I have two nitrate ions here and two nitrate ions here again no change so if they're not changing are they really participating in the reaction no they're not they're what are known as spectator ions ions that do not participate in the reaction they are just present on both sides of the equ they are present on both sides of the equation and usually they're just used to get the other ions into solution so my pottassium and nitrate aren't participating in the reaction that makes them spectator ions so my potassium and my nitrate are spectator ions so we can cancel them out they appear on both sides of my equation so I can go ahead and cancel them out that leaves me with with just the ions that are participating the reaction my reaction is really Love Story between my lead and my bromide getting together my lead two my lead two ion reacts with two bromide ions to form lead 2 bromide solid that's the actual reaction occurring we refer to what I've written here as the net ionic equation the net ionic equation displays only the ions that prot participate in the reaction now every chemistry textbook you read in the entire world will tell you that the way that you get the net ionic equation is to write the ionic equation and then cross out anything that appears on both sides and that is the pinky way out that's the pinky finger out way of doing it it's also the hard way and the way prone to give you mistakes here's the easy way to do it and here's the way I did it as an undergraduate and I would recommend that you address it identify your precipitate in this reaction our precipitates are lead to bromide the precipitates always going to be the product of your net ionic equation to get the reactants just split up your product to get the reactance in your that ionic equation just split up your product I've got lead two here so that's going to be one then I've got bromide there don't forget phases and then balance that's the easy way to do it right identify that precipitate and then Break It Up chemistry is easy life is hard uh although life could be very hard um if you're dealing with Miss Piggy on a daily basis write down Miss Piggy m i SS and then Piggy e i g g y piggy all right write the net ionic equation identify the precipitate then write the ions that make up with the precipitate on both sides so we've got an equation here and we're being asked to write the net ionic equation rather than write the full-fledged ionic equation since they're just wanting the net ionic equation I'm going to identify my precipitate my solid calcium sulfide and then I'm going to write the ions that make it up on the reactant side so I have calcium and calcium is going to be at plus two and remember it's on the aquous phase and then it's reacting with sulfide 2 negative also in the aquous phase balance well one one one one so I'm balanced chemistry is easy life is hard let's have you try one all right pause me try it real quickly did you pause me I paused I pause did you pause do we have a pause connection all right oh we sound like dogs dogs we got pause here um oh now I'm thinking Planet of the Apes keep your stinking paws off me um o all right now I'm really thinking planet of the a all right identify your precipitate I think I'm going to watch that tonight the Charlton hon version not the mark wallberg version um oh whoops identify my precipitate too distracted my precipitate is always my solid so I've got magnesium sulfide write the ions that make it up magnesium and sulfide chemistry is easy life is hard ah here's what we've been building to the entire time I'm giving you two reactants I want you to complete the molecular equation in other words I'm wanting you to tell me what two products are going to form then write the ionic equation identify the precipitate identify the spectator ions and write the netic ionic equation for me ah that that's four things deep breath we spent the last couple hours doing each one of these four things as a separate problem so all I'm asking you to do is what you've already done first thing I would do is I'd complete that molecular equation completing that molecular equation also gets us a step towards the ionic equation because what's the first thing we do oh and pause me by the way and try this on yourself the first thing we do when we're writing that molecular equation is we list the ions right I've got silver I've got per chlorite I've got sodium and I've got iodide well remember Outside Inside to form my new compounds so my silver and my iodine are going to form a new compound and my sodium and my perchloride are going to form a new compound now I need to assign phases so I've got silver iodide and I've got sodium chloride my phases do I have have a rule that involves sodium yes anything with a group 1 a element is soluble so it's aquous anything that contains iodine is aquous except for silver silver is an exception so it's going to be a solid now we balance and we're balanced everything is a one: one ratio this is my solid so it's my prec itate what about my spectator ions easy way to identify spectator ions they're always going to be the ions they're always going to be the ions that make up the aquous product and here our aquous product is our sodium chlorate so the ions that make up our sodium per chlorite are sodium and per chlorite so they would be my spectator ions whatever the ions are that are in our aquous product are always going to be our spectator ions so it's sodium and per chlorite remember they have to be ionics our ionic equation we're almost there right we already listed our ions up here we just have to do the products silver iodide is going to stay together because it's a solid sodium for chlorites aquous so we split it up so there's our ionic equation now for our net ionic equation we simply take our product that's our precipitate silver iodide and we split it up into the ions that make it up and we balance and we're balanced Booyah what can I tell you chemistry is easy life is hard also as a paron gift why don't you write down um Beaker write down Beaker meep meep write down Beaker if you've written down Beaker you're free to go why are you still listening bye o why are you still here have you seen the teaser scene in Deadpool that actually a teaser scene to Ferris Beer's day off