all right guys in this video we're gonna go through everything you need to know about ligand substitution reactions okay so there's a lot to unpack here I'm going to go through it as concisely and clearly as possible but there is a lot of information so you're going to have to pay attention Okay this right here on the screen is directly out of the AQA a level chemistry specification so I'm going to read through this quickly to show what you're going to learn by the end of this video feel free to pause read yourself or completely skip this section if you're not too bothered I'm going to break it down throughout the video anyway in far more detail so feel free to skip ahead right so ligands we're going to look at what they are first off you need to know what the monodente ligands are water ammonia and chloride ions all right next up you need to know that the ligands ammonia and water are similar in size and are uncharged okay you also need to know the exchange of the ligands ammonia and water or h2o occurs without change of coordination number so for example you're going to be using these in reactions with Cobalt 2 plus and copper two plus and we're going to look at what is a coordination number what does this mean you also need to know that substitution reactions can be incomplete for example the formation of this guy right here this copper complex we'll look at that as well you also need to know that the chloride ligand is larger than ammonia and water and how this affects the substitution reactions you need to know the exchange of the ligand Water by chloride ions can involve a change of coordination number okay we'll look at that and some example equations you need to know biodontate ligands okay you need to know the names and the structures of both of these as well as the formula okay ligands can be multi-dentate you're going to have EDTA as our example we'll look at that as well heme all right these last three bullet points are all to do with hemoglobin now there aren't specific heme involving equations or reactions you need to know but there's some extra bits of information that are really important and they can throw in some random one two three Mark questions to do this so I thought it's best place to include in this video right as I said there is a lot to unpack here okay a lot of people struggle with this topic so let's try and break this down step by step and see what's going on so mono dentate ligands first off we're going to look at what is a ligand and what is a complex these are really fundamental concepts that you need to understand okay so what is a ligand and what is a complex okay a ligand is simply an atom ion or molecule which can donate an electron pair okay donates electron pair and what sort of bond does it form a coordinate Bond all right so let's write that out right so that's the first definition written out that you need to know a ligand is an atom ion or molecule that can donate a lone pair of electrons to form a coordinate bond this part about forming a coordinate bond is not required for the definition but it's really helpful to understand that concept what is a coordinate Bond exactly the same thing as a dative covalent bond okay this is a year one concept let's say we draw out a bond here okay just a straight line to signify a bond let's say we have atom a and atom B okay one of the electrons is from atom a one of the electrons is from atom B now this is a typical covalent bond where it's a shared pair of electrons now let's say we switch this up to be coordinate you get rid of one of the electrons and both of the electrons in the covalent bond come from one of the atoms so for example both of these guys come from atom B in this example just using random letters here but each of these would be a very specific atom in a proper equation or a structure so it's exactly the same thing as a coordinate Bond let's move on that's some Theory out the way what is a complex okay you're going to see this word thrown around all over the place when it comes on to transition metals and aqueous ions all those sort of things it's simply a central metal ion surrounded by ligands okay so that's our second definition done really simple Central metal ions surrounded by ligands so I'm going to break down the monodentate ligands right now and then I'll show an example structure of a monodentate ligand complex that we're going to have here now I'm not going to focus on all of the shapes that you need to know I'm going to do that in a separate video for all of the complex shapes and isomers that'll be released soon but for this video I'm just going to focus on the actual ligand substitutional reactions and everything you need to know for that so let's cover the monodentate ligands there's three you need to know what are they okay we've got H2O what's the other one NH3 and then lastly we've got chloride ion now these two right here H2O and NH3 water and ammonia these aren't neutral okay they don't have a charge on them these are molecules whereas this guy right here the chloride this is an ion and it has a charge and we're going to look at how that affects the ligand substitution reactions in a little while so you're going to see this word thrown around a lot okay dentate and mono so it's going to have mono is referring to one right it just means one and dentate is referring to the number of coordinate bonds that that respective ligand forms so you need to know mono dentate or one coordinate Bond you need to know by dentate two coordinate bonds and you need to know multi-dentate which is just anything more than two for the AQA specification it's going to be six and I'll break down what that example is so let's say we look at water as an example we're going to be forming What bond are we going to be forming coordinate Bond okay because it's a ligand right so this is where the lone pair is going to come from it's going to come from the oxygen very similar to organic mechanisms right the lone pair is going to come from the oxygen now let's say we're dealing with an example of a copper Central metal ion right here a copper two plus as an example what's going to happen here is this H2O molecule is going to form a dative covalent bond with this copper okay now you don't normally show it like this if you wanted to show it specifically what you would have here is the copper like this in the middle and then you would have simply an arrow and that's how we show a coordinate Bond you don't need to show the lone pair and you don't need to show a curly Arrow like in Organics this is inorganic chemistry so we show a coordinate Bond or a dative covalent bond simply with an arrow so when we're dealing with mono dentate ligands you're going to be forming a different number of coordinate bonds okay and we refer to this simply as coordination number now coordination number is simply the number of coordinate bonds involved in a complex and as I said I'll show an example in a second but before I do that I just want to briefly cover where the lone pairs come from so you need to know this okay so in a water molecule as I said the lone pair is on the oxygen in ammonia the lone pair is on the nitrogen and in chloride ion is pretty simple there's just a lone pair on the chlorida okay now how many coordinate bonds are able to form when we're dealing with water and ammonia you're going to be dealing with six okay you're going to be dealing with six coordinate bonds forming therefore the coordination number equals six so let's roll this out H2O and ammonia equals six coordinate bonds so you will get a coordination number of six right for the entire complex now a slightly different for chloride ions chloride ions are going to give you a coordination number of four and that is because they form four coordinate bonds around the central metal ion okay so let's look first off at some example equations when we're dealing with water or ammonia okay let's start with these two and then we'll move on to Chloride after and I'll explain why the coordination number changes from six to four okay okay so let's look at some example ligand substitution reactions you need to know for ammonia and water okay the examples given in the specification is for Cobalt two plus and copper two plus okay so let's draw out the equations for both of these see what happens with ammonia and H2O and you should be completely fine if you just remember these two so how do we draw a complex as a formula what you want to do is you want to start by opening a square bracket okay now in physical chemistry this would denote concentration right when you're doing a calculation it would denote concentration whereas inorganic chemistry it's going to signify a complex okay an aqueous complex or an aqueous ion complex whatever you want to call it this is what it's showing you okay so after the square bracket you want to show whatever the central transition metal ion is so let's use this example of cobalt and we'll Chuck that in right there next up you want to use rounded brackets outside of whatever ligand is present so I'm going to be starting with a water ligand and that's what you need to be aware of for these initial ligand substitution reactions is you're starting with what's referred to as a hexa Aqua complex okay hexar just meaning six Aqua meaning water okay six water molecules right here so rounded bracket H2O close the rounded bracket and then you have to show how many of these ligands are bonded on by a lower subscript so in this case it's going to be six right then we close the square bracket this is our complex are we finished no you have to show the oxidation state or otherwise known as the charge of the entire complex so if we're starting with a Cobalt two plus and we've got six water ligands what is the charge on water ligand it's neutral it's zero right so two plus six lots of zero is still two so it's just going to be two plus okay what is the state of this it's aqueous all right so this is our aqueous hexa Aqua Cobalt two plus complex it's real mouthful but that's what we're starting with now we're going to be substituting all six of these water ligands with ammonia okay I'm going to show that right here so we're adding ammonia right here how many did I say that we substituting it with six so we put six to signify six moles of this ammonia molecule right here and this is also aqueous okay this is all taking place in solution so we're going to form our new complex here our new cobalt complex now going to be exactly the same thing square bracket what is our transition metal center Cobalt what is our ligand it's no longer water it's going to be ammonia okay so we're going to Chuck that in our rounded brackets six of these guys okay all six ammonia ligands substituted the water ligands so we've still got six of those guys what's the charge what is the charge on ammonia neutral okay zero exactly the same charge here so it's still going to be two plus okay and now the last thing we have to show on top of the uh the state is the six water molecules have now been kicked off okay so this equation is super simple to remember just remember six is replaced by six six okay that simple all you have to get correct is the square brackets okay the rounded brackets surrounding the ligand right here and then the overall charge on the complex if you remember that and you remember that it's fully substituted or completely substituted with all six you'll be completely fine now what is the color change here okay now a lot of students absolutely stress about this including myself guys when I did my a levels I did the previous specification okay the pre-2016 spec and I had to remember every damn color you don't have to remember the Cobalt colors anymore okay AQA has not been very clear with this I see it in the textbook so I see it on online resources and online YouTube videos you don't need to know the Cobalt 2 substitution reactions color changes okay I'll link a AQA specific teaching guidance document that specifically outlines that these substitution reactions involve in Cobalt 2 plus color changes of reactions and products are no longer required okay so I'll link that down below if you're absolutely stressed out and you think you do have to learn them you don't okay so we're going to skip the colors here but we'll look at the colors of the copper complexes okay the copper two plus let's look at that equation right here and you have to know this this is really really important and it's slightly different okay so so far I've been throwing round the word complete that essentially means that all six ligands are replaced by all six of some other ligand right in this example ammonia what you need to be aware of with copper 2 plus is we get what's referred to as incomplete ligand substitution okay what does this mean it just simply means that not all six of the water molecules or water ligands are substituted and kicked off okay we're going to get partial substitution occurring I like to use the word incomplete because that's the one AQA likes but you can also say partial that's completely fine now this is always the case with copper okay when we use excess ammonia just keep that in mind when we use excess ammonia you're going to get this occurring now I'm not going to go into too much detail regarding limiting and excess reagents I covered all of that in my every observation and equation you need to know for aqueous ion reactions okay whereas in this video I'm just going to focus on the ligand substitution reactions so all you need to know here is that for copper two plus incomplete substitution occurs so what is our equation here we're going to start with exactly the same thing but just swapping out this Cobalt with a copper okay so it's going to be copper let's draw this in red copper right here water molecule to start with we're dealing with a hexa aqua copper II complex okay what is the charge here two plus exactly the same what is the state aqueous okay all of this is aqueous this is a liquid actually I should have put liquid there while we're reacting it with we're not reacting it with six moles of ammonia because we're dealing with incomplete substitution only four moles or four ligands of ammonia are reacting here that's also aqueous okay so what complex is forming here I'm going to draw it very similar now we're going to have four moles of ammonia that came from this right here okay so you're going to draw that in rounded brackets signifying the four ammonia ligands okay and there's four of those guys now there's still two water ligands remaining because only four have been substituted or kicked off of the molecule so it's going to be H2O here two close the square brackets what is the charge both of these are neutral okay they're both zero so the charge is exactly the same this is aqueous okay and then we're going to be kicking off four of the water molecules because four have been substituted by four ligands of ammonia so that's gonna be four H2O and again the state is liquid right there now this is something you need to know from the spec okay what is the colors what is the color change and what is the coordination number change so it's really important that you understand with these neutral ligands there is no change in coordination number okay what is the coordination number of this starting hexa Aqua complex six okay there are six ligands each ligand forms one coordinate Bond so our total six times one is six okay now over here we have ammonia but this is still only forming one coordinate Bond per ligand so we still have a coordination number of six okay now this one this copper two plus ligand substitution the incomplete substitution we're going from six right here to how many four plus two still six okay there is no change in coordination number now this switches up for chloride ions which we'll check out in a second but just remember for ammonia and water the neutral ligands involved in the specification there is no change in coordination number okay just keep that in mind right with coordination numbers out the way what is our color change going to be this right here this copper hex Aqua complex aqueous is going to be blue okay it's a blue solution now what do we change to here what is the color of this complex it's a deep blue solution okay from Blue to deep blue making sure to mention that it's a solution okay these are both aqueous this is not a precipitate all right guys so going back to our specification real quick we've covered these monodentate ligands I haven't explicitly said that these are similar in size okay the ammonia and the H2O but we'll look at that right now when we delve into the chloride ion ligand substitution but I have said these are uncharged now we've looked at two examples of ligand substitution reactions Cobalt 2 plus with the complete ligand substitution with ammonia and the incomplete ligand substitution with ammonia and copper two plus so we've looked at that now we've also looked at this right here this is also in the specified which I just mentioned incomplete okay really important that you know this next part we're going to look at is chloride ligands okay how are they different to ammonium water and you need to know the equations for the examples of cobalt two plus copper two plus and iron three plus and we'll look at that right now all right so as I said from the spec guys we need to know copper Cobalt both of those two plus and then iron three plus State okay so let's draw these out all right so I've drawn these out now when we add a solution of chloride ions so for example you could come from concentrated hydrochloric acid right when we add a solution of that to this a solution of hexa Aqua complexes whether it's copper Cobalt iron it doesn't really matter you're going to get another ligand substitution reaction at current okay the chloride ions are going to come in and substitute these water ligands all right that's just something you have to be aware of and we'll go through the equations right now now another thing you have to be aware of from the specification is let's say we have our neutral ligands right nh2 and H2 where'd that come from H2O and NH3 right these are uncharged and very similar in size how we know they're similar in size they're Mr okay their number of protons and neutrons H2O their molecular mass or their Mr is going to be 16 plus 2 which is 18 right NH3 what's the molecular mass of nitrogen 14 plus 3 is 17 right so these are very similar in mass and size so let's look at chlorine now we've got chlorine chlorine is a big boy okay chunky monkey what is the mass of chlorine the molecular mass of chlorine is 35.5 it's basically double these guys all right so in this case with chloride ions you cannot fit six around the central transition metal there's just not enough space okay so the maximum that you can fit around a transition metal in these instances is four okay so just remember that these are bigger then that is the reason why you can only fit four chloride ion or chloride ligands around a central transition metal so what does this mean then we're going to get a change in coordination number okay the number of coordinate bonds bonded onto that Central transition metal is going to change and we'll look at that right now and we'll go through the different color changes right real easy guys so four CL minus so Plus for cl minus plus 4 CL minus okay these are also aqueous now what is this going to produce it's going to produce another complex okay another aqueous complex and we're going to get complete ligand substitution okay even though we're reacting with four moles and not six because of the size and the charge difference we kick all six of these off replace it we have a slightly different shape which is tetrahedral I'm not going to go into shapes in this video but just realize the shape does change but we're still getting complete ligand substitution so let's draw out what our complex is going to be still got the central transition metal copper and we're going to get four chloride ions surrounding this okay and the way you draw this out is slightly different okay we're not going to be showing the rounded brackets on the chloride ions you literally just put cucl or whatever the transition metal is followed by CL close the square brackets and then put the charge to the top right now can you guys work out what the charge is going to be here if we've added and substituted these water ligands with the chloride ligands which have a minus one charge okay real simple here we've got two plus four times minus one so that's exactly the same thing as two minus four so we're going to get an overall charge here of two minus okay minus two charge right here now all that's left to do is put in our state symbol and kick off all six moles of water ligands all right so we're going to kick off those six water ligands right here and this is a liquid now don't get too stressed out about the states it's good to understand them so in the color changes you can say whether it's a solution or precipitate it Etc but normally AQA is pretty kind unless they say state symbols are required you can leave them off you should be completely fine it says that in the mark scheme of the past papers okay just make sure to include them if they do ask for them which they definitely can okay right so I've drawn out our other equations that you need to remember I've left one thing off on purpose guys what is the charge of this ironcl4 complex is going to be a one minus okay because we're starting with a three plus instead of a two plus you're going to be dealing with a one minus charge okay just keep that little caveat in mind and you'll be completely fine so what are our color changes going to be as I mentioned you don't need to know the color changes for the Cobalt 2 plus but I'm going to include it in this video just in case you want to know okay so I might as well include it so copper two plus what does this start as exactly the same as it in our incomplete ligand substitution this is a blue solution okay what is our product going to be this cucl4 2 minus is going to be a yellow solution yellow solution all right cool now I'm going to go over the Cobalt really quickly it's going to be pink pink solution right here and what is our Cobalt cl42 minus blue okay blue solution again AQA specify you no longer need to know the color changes for the two plus Cobalt reactions so just keep that in mind don't have to memorize these what is our starting hexa Aqua iron 3 plus complex technically this is purple okay purple violet or Lilac okay all of these colors are accepted I like to remember purple because it's really easy now something you really have to keep in mind here is even though the true color of this is purple in solution you normally don't get this okay this would normally appear as a yellow brown solution and the reason for that is it's been deprotonated once and you're left with Fe h2o5 oh okay you're left with this and this I don't know why I drew it in purple but this is a yellow brown solution okay so even though purple is correct you can also put yellow brown solution okay just keep that in mind and what is the color of our solution right here yellow okay another yellow solution forming here so do your best remember these color changes these color changes and you should be all good to go now something really really important here you need to keep in mind because the AQA can try and trick you if in a question they say solid copper chloride so copper chloride right here cucl2 this is a solid okay if this is dissolved in water if they say solid copper chloride is dissolved in water it's not going to be this it's not going to be cucl42 minus is going to be this okay and that's because the CU CO2 it's because it's cu2 plus C or minus there's two of these guys so it's going to be cuc02 when that dissolves in water it forms this okay just keep that in mind they may try and trick you they might not be that mean anymore but I've seen it come up before so just keep that in mind just remember it's the aqueous CU h2o62 plus complex okay just keep that in mind all right guys going through the spec taking it off step by step we've said that the chloride ligands are larger than the uncharged NH3 and H2O done we've looked at the different substitution reactions that occur with chloride ions involving our Cobalt 2 plus copper 2 plus and fe3 plus and how they have a change in coordination number okay goes from six to four next up let's look at our bidentate ligands all right guys by identity ligands there are two you need to be aware of okay you need to know the formula as well as the structure and the shape I'm not going to go through the structure and the shape in this video I'll save that for a different one but you do need to know the formulas so what are the two we need to know first one is ethane12 diamine okay real easy one here you're gonna have an ethane in the middle so a ch2 ch2 and then here we can see it's a one two diamine so it's just going to be an nh2 on either side now in an equation you don't really want to show the bonds right for the formula you just want to show you just want to show what atoms are present so it's going to be nh2 ch2 ch2 nh2 okay that is our ethane12 diamine the other one you need to know is a charged ion okay let's write that down here ethane diorate okay ethane diorate what does this look like real easy one C2 o4 what is the charge here two minus okay now we'll save the shapes of these for another video because you need to know about isomers and and shapes and bond angles and stuff like that but for the sake of the biodente ligand substitution reactions what do you need to know by okay what does it mean when it's by identity it means that every single ligand that is present is going to form two coordinate bonds okay by meaning two so let's look at this first one this ethane one two diamine where are the lone pairs that are going to be donated to form the coordinate Bond there's one on this nitrogen and one on this nitrogen all right pretty simple on this one right here I have to kind of show this the shape really don't I sew is going to be o c double bonded carbonyl group right here another carbonyl group and then an O okay the lone pair is right here okay so this is going to go on form a coordinate bond with the central metal whatever that may be and it's going to form two coordinate bonds per one ligand all right so just keep that in mind right so let's draw out our equations that you need to know again starting with a hex Aqua complex real simple stuff I'm going to start with a copyright but you can swap this out for any metal it doesn't specify in the specification which metals are going to be used as an example so I'm just going to use copper right here now six water molecules or six water ligands two plus charge right here this is going to react with how many ligands all right if we get in complete ligand substitution occurring all six of these water molecules have to be kicked off and substituted so are we going to react with six moles of this guy no we're not okay if we reacted with six moles of this you're going to get 12 coordinate bonds forming that's way too many okay each molecule is forming two coordinate bonds so we just have to halve the number of moles so it's going to be three lots of this okay so I would put three moles of the nh2 ch2 ch2 nh2 all right easy peasy I'm going to leave off the states here but this is all aqueous and then this is going to form our new complex okay what is our complex going to be you literally just have to change the water inside this bracket with this right here and change the six to a three charge stays exactly the same in this instance because this bindate ligand is neutral so let's draw that out we're going to have our square bracket copper nh2 ch2 ch2 nh2 closed rounded bracket three of those guys charge stays exactly the same all right easy as that guys all six water molecules have to be kicked off okay not too bad that is our equation that you need to know for the bidentate ligand substitution involving ethane 1 2 diamine now let's look at ethane diorate and see how it's slightly different right so I've moved things around slightly because I realized I wrote this equation under the ethane diode but that's not what you want to do okay so let's start with our same example I'm going to use copper again so copper hexa Aqua complex six of those guys two plus okay now we're reacting it with ethane diode this is all you have to write okay you don't have to write it out in any other format this is completely fine how many moons of this exactly the same okay I'm gonna get three moles three moles because each ligand has two coordinate bonds I know I'm repeating myself but repetition sometimes really helps out in making sure that you remember that these little caveats of information okay what is this going to form real easy replace the water or substitute the water with this that's why it's called a substitution reaction okay pretty simple stuff so let's draw this out copper rounded bracket we're going to show our c204 close rounded bracket how many of these guys there's three what is the overall charge now this has a two minus you don't want to put a two minus in the rounded brackets or outside the random bracket something like that you do not want to do that because now this is a complex okay this is an ion this is a complex so you want to show the charge outside the square brackets so what we're doing here is we're going from A2 Plus and we're minusing three lots of two minus Okay so three lots of two minus exactly the same thing as two minus six which equals minus four so this charge is going to be 4 minus again same thing with kick six water molecules off all right simple as that that is our other equation that you need to remember just remember that they may ask you to swap this out for a different transition metal iron chromium nickel whatever it may be they can test you on different things when it comes to this now if I was to ask you is there a change in coordination number here what would you say no there is no change okay we're going from a coordination number of six to a coordination number of six okay even though there's only three ligands here each ligand forms two coordinate bonds so we have three times two which is six okay exactly the same coordination number here nothing changes all right so we did that not too bad let's look at multi-dentate ligands okay this this guy right here EDTA four minus all right so I'm going to draw out EDTA four minus and show you what it looks like you don't need to remember this shape okay you just have to remember the formula EDTA four minus they make it pretty easy for you but I'm just going to draw it out so I can show you where the lone pairs come from to form those coordinate bonds all right guys so this is our e d t a right EDTA four minus that's all you need to know it as elite four minus when you're writing out your equations this is way too complex okay so where do our coordinate bonds come from there's a lone pair right here lone pair right here there's a lone pair on the nitrogen as well on the on both of these nitrogens and there's a lone pair on the other two oxygens okay there's a lot of symmetry going on here if you split this molecule in half you can see perfect symmetry okay so each nitrogen and oxygen has a lone pair ignoring these ones okay the lone pair does not come from the carbonyl it comes from the negatively charged oxygen right here so if I showed you this structure and I said okay how many coordinate bonds is this going to form it's going to form six okay so even though we have one ligand each of these EDTA four minus ligands is going to form six coordinate bonds so in that case we're going to get complete ligand substitution occurring with only one ligand right so let's draw out an example equation here for this ligand right here this EDTA so again I'm going to start with copper as my example two plus right this is our hex Aqua complex plus EDTA okay that's all you have to write it as I keep repeating myself but that's literally all you have to do EDTA four minus pretty simple now all six of these water molecules is going to get kicked off because we're dealing with six new coordinate bonds right here okay so our complex is just going to be copper rounded brackets replace the H2O with the EDTA okay close rounded brackets square brackets for the complex and then the charge has changed okay two plus minus four is just minus two so we're going to have a two minus charge right here and then all six water molecules got kicked off right this is our equation that you need to remember really simple one again this can be swapped out for a different transition metal just keep that in mind therefore the charge on the overall complex may change for example if it's an fe3 plus okay just get in mind all right not too bad we've covered the multi-dentate ligand that's everything you need to know it's not too complicated there right so let's move on to our last three bullet points this is all about hemoglobin okay heme and hemoglobin not really involving any sort of substitution reactions here but it still involves coordinate bonds so I thought it was some useful information to throw on at the end of the video and then after that we'll go into some practice questions so if you don't really want to know about heme feel free to skip ahead do some practice questions okay it's really important that you revise do some practice questions test your knowledge and do some active recall so I'm going to go over this super quickly it's all you need to know guys is straight out the specification there's no more crazy information that you need to know so I'm going to read this out right here so heme is an iron2 complex okay and fe2 plus complex and it contains a multi-dentate ligand all right next up oxygen forms a coordinate bond to fe2 in hemoglobin and this allows oxygen to be transported in the blood okay that's literally all you need to know there's not it doesn't get more complicated they're only going to be able to throw in some one or two mock questions for this okay next thing is carbon monoxide okay carbon monoxide is incredibly toxic to mammals okay humans as well because we're mammals um but carbon monoxide can form a strong coordinate bond with hemoglobin okay and it can displace oxygen okay it's stronger than the bond that hemoglobin makes with oxygen Okay so you can replace it you can build up in your blood and kill you all right pretty much that so it's incredibly toxic and you do need to know this okay it can replace oxygen inside the hemoglobin molecule and why is that because it forms a stronger Bond okay if you guys do biology you'll be fully aware of this all right some test yourself question guys going to start with some easy ones here and then move on to some slightly more difficult ones so first one what is a ligand and what type of bond can it form so pause the video work through these questions see if you get them right so what is a ligand guide the definition you need to remember is that it's a molecule atom or iron that can donate a pair of electrons to a central metal ion okay all right that's the first Mark what type of bond can it form pretty simple coordinate Bond okay not too bad two marks in the bag question two describe what it means for a ligand substitution to be incomplete and give an example equation for this type of reaction okay so I may not have explicitly said this in the video okay so incomplete ligand substitution is when one ligand is only partially replaced by another in a complex okay not too bad here what is our example equation there is only one that you need to know involving copper two plus so let's draw that out right now done guys okay real simple one here just remember four moles of ammonia four moles of water are kicked off and substituted okay and this is the incomplete Logan substitution reaction you need to know all right question three guys ethyl one two diamine is an example of a bile dentate ligand name a different biodontic ligand and write an equation for a reaction involving this ligand and a solution containing aqueous Iron II ions right so can you remember what the other bilentate ligand is that you need to remember diorate okay ethane diorate and what is the symbol for this c2o4 2 minus okay so let's draw out an equation for this reacting with an aqueous Iron II ion complex and see what's going on here all right guys easy as that remember we've got three modes of the ethane direct reacting here because each one of these ligands forms two coordinate bonds so six of these guys is replaced by three of these but our coordination number does not change okay what does change is our charge okay two plus three lots of two minus so two minus six is four minus and that is our change in charge or oxidation state whatever you want to call it completely fine and that is our example equation from this question hopefully you guys got that right all right guys last question here question four write out the equation for where a hexa aqua copper 2 complex reacts with conch HCL and explain what happens to the coordination number all right so let's draw out our equation here using copper two plus all right cool I've written out our equation here six water ligands are kicked off and replaced by four chloride ions this is still complete ligand substitution okay but we're getting a change in coordination number so what we have to do next is explain what happens to the coordination number it changes from six to four and we have to explain it okay explain is our Command word this just describes it we're just changing it from six to four why is that the case it's because chloride ions are larger okay and that is why only four are able to fit around the central metal ion all right that would be our answer there that was our final question let's go back to our specification tick things off last three things here was just to do with hemoglobin that's really easy just memorize those fine details and you'll be completely fine I put a ton of time into this video so I really hope you found it helpful if you did like the video it really helps the channel out if you have any questions let me know down below and remember guys I have not included the shapes the bond angles and the isomers of these complexes and I haven't included the chelate effects okay the chelate effect is more to do with entropy Gibbs free energy and enthalpy change and it's to do with the stability of these complexes but I will save that for a different video this video was just focused on the ligand substitution reactions themselves okay so keep that in mind realize that you have to learn this go through the specification yourself cater it to you take it off as you go do practice questions okay all of this is incredibly important best of luck with your revision and upcoming exams guys until next time peace