The following diagram represents an ionic compound in which the red spheres represent cations and the blue spheres represent anions. Which of the following formulas is consistent with the drawing? KBr, K2SO4, Ca1NO322, Fe21SO423.

Video transcript

Welcome back everyone consider the diagram below. That illustrates an ionic compound. The cat ions are represented by light green spheres and the ann ions are represented by purple spheres, choose among the following compounds that match the given illustration. We have aluminum, oxalate, barium, acetate, rubidium chloride and sodium dick roommate to choose from. So if we know that light green spheres represent are an ions. We would count a total in this image. Sorry, a total of our light green spheres being and sorry, are light green spheres are cat ions, not an ions. So we would count a total number of cat ions being 20. And then for our purple spheres Which represent our an ions, we would count a total of just 10. Simplifying this ratio, we can say that we have a ratio between to cat ions 2 1 An Ion. So recall that are given compounds are all ionic compounds and we want to recall the ionic compounds consists of metals plus non metals or metals plus polly atomic ions and they're essentially just considered salts. So they're going to disassociate into their ionic components or dissociate as ions. And so beginning with our first compound, aluminum, oxalate. We have a L two c 204 in parentheses with a subscript of three. This salt is going to completely dissolve into two moles of our aluminum, three plus ions. We know that it's three plus, since we have that subscript of three outside of our parentheses. And sorry, there should be a parenthesis here And then we would also dissociate into three moles of our poly atomic ion being oxalate C204 with a two minus charge, since aluminum has that subscript of two and we know that the charges of our ions swapped in our chemical formula. So based on this dissociation we can see that we have two moles of our three plus aluminum caddy on 23 moles of R two minus oxalate an ion which does not match our ratio. So we know that this compound is not in our illustration because again we need a 2 to 1 caddy into an ion ratio. So we can rule our first compound out actually, we'll just cross it out here. So now moving on to our second compound, barium acetate which is B. A. And in parentheses we have CH three C. 00. With a subscript of two on the outside this salt is going to dissociate into one mole of our barium two plus Catalan we know that it's a two plus cat and because we have that subscript of two outside of our acetate poly atomic ion and then we have two moles of our acetate, an ion CH three C. 00 minus and it's a minus one since barium has a subscript of one. But we also should memorize this poly atomic ion in general chemistry. So looking at our ratio between Arkady into an ion, we have one cat eon of barium for two moles of our acetate an ion. And so this does match or rather no, we need to carry ons for one, an eye on. And so we have to an ions here for this compound. So this actually does not match. And we would rule this out as being depicted in our illustration. Moving on to our third compound, we have rubidium chloride. This salt is going to dissociate into one mole of our rubidium plus one caddy on, plus one mole of our chloride, one minus an ion. And here we can see we have a 1 to 1 ratio between Arkady into an ion which does not match our illustration. So we can roll it out from our choice and then we have lastly sodium dye chrome eight and a two cr +207. This salt associates into two moles of our sodium plus one catty on and one mole of our di chrome eight an ion which is a two minus an ion. And sorry, all of our ions. And each of these dissociation should have the label since they are dissolved ions. And so note that we have for this ratio two moles of our cat ions to one mole of our an ion which does match our illustration ratio between our Canadians to an ions being the green spheres to purple spheres. And so because this illustration or sorry, this ratio matches our illustration, we would say that therefore sodium dye chrome eight matches our illustration. And so our final answer is going to be our formula sodium dye chrome corresponding to choice D. In the multiple choice as the correct answer. So I hope this made sense and let us know if you have any questions.