What is the formula, including the charge, for each of the following complexes?

(a) An iron(III) complex with six water ligands

(b) A nickel(II) complex with two ethylenediamine and two bromide ligands

(c) A platinum(II) complex with two chloride and two ammonia ligands

Video transcript

Hi, everyone. Welcome back. Our next problem says, determine the formula and charge of these given co-ordination compounds. We have three different coordinations, complex names and our answer choices A through D are different formulas for each of these. So let's just look at each of these. In turn, number one says a copper two complex with two water ligands and four cyanide ligands. So to write out the formula, we start with open bracket for a complex copper is cu we have two water ligands. So open parentheses h2o closed parentheses, subscript two and then four cyanide ligands. So open parentheses CN subscript four and then closed brackets. That's our complex, but we still need to determine its charge. So we would say our copper, we know it's copper two. So its charge must be positive two, water is neutral. So it gives a charge of zero cyanide has a charge of negative one and there's four. So four multiplied by negative one, the charge of the cyanide is negative four. So our overall charge will be two plus zero minus four will be two minus for the overall charge. So let's move on to number two. Although it might not be a good idea before we do that to double check our answer choices and see if we can eliminate any that have incorrect formulas for number one on a test, that's a good way to quickly get to the right answer and maybe not have to work through every single problem. So if we look at choice A, it has cu H2O 2 CN four overall charge of two minus. So this has a correct formula for the first compound. But choice B shows an overall charge of just negative one. So that's incorrect. And choice B is therefore incorrect. Choice C also sergeant shows a charge of negative one. So it's incorrect. But choice D shows the correct charge of negative two. However, when we look closely at the formula, it lists only two cyanide ligands instead of four. So we've actually eliminated BC and D. So I'd be very lucky on a test because I could right away without even looking at the other two complexes. I'd have my answer of choice A, it's the only one with the correct formula and charge for complex number one. But we want to be thorough here. So we will look at our other two complexes. Number two says a gold three complex with 3D NDEN ligands. Diane is dy Elaine, it is a neutral ligand. And so we write our formula with open bracket. The abbreviation for gold is A U. It's one of the Latin ones and diane. Of course, open parentheses, lowercase dien closed parentheses, subscript three and then close brackets. Diane is neutral. We know gold three as a charge of positive three. So our overall charge is three plus and we confirm that in choice. A we have this correct answer for complex number two. Finally, we'll look at number three. A ruthenium three complex with two ethylene diamine ligands and two thiocyanate ligands. So we have open bracket. Are you for your Bruni ethylene diamine has the Nick has the or abbreviation I should say of en lowercase E lowercase N and it has a charge of zero, it's neutral. We know we have two of those. We've got open parentheses, en subscript two after the closed parentheses. And we have two thiocyanate ligands. Thy Nate is SCN sulfur carbon nitrogen and it has a charge of negative one multiplied by two since there are two of them. So it has a charge of negative two. So we'd put open parentheses, SCN close parentheses, close brackets, our charge on rhenium, it's Ruini three. So it will be positive three. So our overall charge will be positive three plus zero minus two. Just be a single positive charge on the overall complex, which if we look at choice. A number three is indeed the formula written and the charge written. So once again, the formula in charge of each of these compounds is found in choice A cu H2O 2 CN four overall charge two minus for number two A U dien three overall charge positive three and number three are you en two SCN two overall charge positive one? See you in the next video.