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the concept of spectator ions comes up really frequently in chemistry so in this video we'll look at a definition and examples and we'll give you some practice identifying spectator ions so we have a chemical reaction like the one here we have our soluble substances they'll say aq that means they're aqueous and dissolved in water then we'll have things like solids liquids and gases here we have a solid so this is actually just a solid at the bottom of the test tube after this reaction if we break this up into the ions just the ones that are aqueous and soluble this is what we get so this is what's called a complete ionic equation it shows all of the ions and then it shows any solids here like this that we didn't split up when we're talking about spectator ads we're looking for things that are the same on both sides so pause and try to figure out what's the same on both sides of this complete ionic equation those will be the spectator ions i didn't write aqueous for everything i just showed the solid here but all of these would be aqueous so i have ba2 plus here nothing on this side like that this is bonded to the sulfate chlorides i have two chlorides here and here so these are spectator ions and we would cross those out we're not really interested in those two potassium ions here in the reactants and in the products these are spectator ions get rid of those and then what's left that's what we call a net ionic equation that would look like this in our net ionic equation we don't have spectator ions let me write the states in so we have these two aqueous ions they come together we get this barium sulfate which is a solid it's a precipitate falls to the bottom of the test tube spectator ions are the same on both sides so pause and identify the spectator ions here in the complete ionic equation this is our original equation it's already balanced here's our complete ionic what are the spectator ions as we look at it we have fe here and fe2 plus those are different we have a solid aqueous those aren't spectator ions same for the copper these are different the only thing that's the same that's the sulfate ion this is the spectator ion if we cross these out what's left would be a net ionic equation let's try another one first let me balance this you have to balance this molecular equation first before you work with ions i think a 3 here and a 3 here so now we've balanced this and i should put my states in as well so here i've split them up in the ions and everything's aqueous except for this iron three hydroxide that's a solid and notice how these subscripts here they show up again when we write the ions that's important we need to balance the equation because it'll show up here as well so pause and identify the spectator ions i have three chloride ions here and right there those are spectator ions three sodium ions three sodium ions and what's left that's the net ionic equation so identifying the spectator ions is pretty easy they're the same on both sides and we know the ions those will have the plus and minus after them but it's a little more challenging to know which ones are aqueous and which ones are solids and then how do you know these charges for each of the substances so let's take a look at an example and explain how we do that so there are two ways to figure the states out for each substance the first is memorize the solubility rules this is pretty helpful so we see that here the nitrate ion no3 minus pretty much soluble all the time that means it'll dissolve so anything with the nitrate after it that's going to be aq potassium nitrate over here so that's easy we can also see group one elements like this potassium here they're going to be soluble so we can write an aq here so all we have left to figure out is this lead to iodide the solubility rules tell us when we have something like iodine in general it's going to be soluble unless it's bonded to lead silver or mercury so this is insoluble it's not going to dissolve because of that it's going to be a solid that means it's going to sink to the bottom of the test tube as a precipitate so when these two substances react we get the solid so this is probably the best way to figure out what the states are for each substance you can also use a solubility table if you're allowed by your instructor but the solubility rules are usually quicker and more effective let's figure out about the ions next when we're finding the charge on ions we have polyatomic ions like the nitrate you have to be able to recognize them some teachers that use a chart like this where you can see the nitrate ion has a negative charge others want you to memorize it i would recommend memorizing things like nitrate sulfate some of the common ones so we know that the nitrate is going to have a negative charge since there are two of them that means the lead is going to have to be two plus that's a transition metal we don't always know its charge for these other elements here we'll need to look at the periodic table so on the periodic table we didn't see lead because it's a transition metal we had to figure it out but for potassium that's right here in group one that'll be one plus iodine right here over here group 17 7a that'll have a negative charge and now we can split these up into their ions pretty easily we could say we have pb 2 plus and i won't write aqueous each time plus 2 nitrate ions plus we have two of the potassium ions and the two goes to everything so we have two iodide ions and those are the reactants in the products we don't split solids liquids or gases apart so we're just going to have that pbi2 which would be a solid and then we have two potassium ions plus two nitrate ions so now we're back to just identifying our spectator ions pause see if you can figure out which of these are spectator ions so we have two nitrate ions in the reactants and two in the products these haven't changed they're spectator ions we can cross those out two potassium ions here and then in the products two potassium ions those are good so these are the spectator ions in this reaction if i want the net ionic equation i just remove these right in the states clean it up a bit and with those spectator ions removed i only have what changed in the chemical reaction and what's nice is you can check if you're right you have 2 plus and then two times one minus two plus and two minus that adds up to zero this is a neutral compound so its charge all adds up to zero if you count the atoms up they're balanced that's a good way to check so we found the spectator ions we crossed them out and we were left with the net ionic equation let's give you one more practice problem and we'll be done so pause and figure out which compounds are soluble then i'll put the periodic table up and you can figure out the charge as well so everything's aqueous except for the silver chloride let's look at the periodic table so we have the charges now split it apart into its ions note this equation's already balanced so these are the ions and the only thing we have that's solid is silver chloride everything else is aqueous cross out the spectator ions and you'll have that net ionic equation here the spectator ions are the nitrate ion and the sodium ion and this is our net ionic equation you'll note that charge is conserved we have a plus and minus here in the reactants they balance out to zero and this is a neutral compound so that's balanced and the atoms they're balanced as well that's our net ionic equation and these those are the spectator ions that we've crossed out so to develop these skills and be able to identify spectator ions you need lots of practice so at the end of this video there's a link for more practice on how to do these types of equations and in the description as well links to finding solubility and determining the charge on ions this is dr b with examples definitions and some practice identifying spectator ions thanks for watching you