Okay, So in this video, we're answering question 108 from Dr 17 which tells us we have a solution that is 170.2 to Mueller and F people. It's too ions and 0.1 for Mueller and MG plus two ions. In part they were asked if potassium carbonate is used to selectively precipitate one of the cat ions while leaving the other cat eye. And in solution which cat and will precipitate first. What minimum concentration of potassium carbonate will trigger participation? Precipitation. Sorry of the cat eye on the precipitates first, um so the possible products we conform with our carbonate eye on our iron carbonate and magnesium carbonate and to figure out which one will precipitate first, all we need to do is to compare the scalability product. Constance those equilibrium, Constance, that air calculated from our amounts of ions and solution. So for iron carbonate, we have a lower liability product constant than for my museum carbonate, which means that iron carbonate is the least soluble in the most likely of department precipitate. While magnesium carbonate is the most soluble in the least likely to form precipitate eso, we're going to form a precipitate from iron carbonate before magnesium carbonate. And we want to know what concentration of que Tu Sio three will trigger the precipitation of r F E C 03 s. So, basically, if there are more ions that Aaron the solution, then there would be equilibrium than some of the solid reactant will have to form in order to reach equilibrium. And we're going to form a precipitate. So basically, when our reaction question Q is greater than our Selya bility product, Constant K um, so are our reaction quotient. Q is equal to our iron ions. Times are carbonate I arms and we know that that needs to be greater than our KSB. So basically, we need our concentration of carbonate ions to be greater than the K S p divided by our concentration of iron ions which were given. So we have 3.7 times 10 to the negative 11 for our ke sp divided by 110.2 To moller, that gives us 1.4 times 10 to the negative nine Moeller That's the concentration of potassium carbonate we need in order to initiate this precipitation of iron carbonate out of solution um, Andy were as what is the remaining concentration of the cat eye on the precipitates first, when the other cat eye on begins to precipitate. So what's the remaining concentration of iron ions wants? Magnesium carbonate begins to precipitate. So when is the other cat eye on going to start precipitating on? When are we going to start forming magnesium carbonate? We need to check when Q is greater than K for magnesium carbonate. So Q is just equal to our concentration of my museum ions, times their concentration of carbonate ions. And that needs to be greater than our K S P, which is 6.82 times 10 to the negative six for my museum carbonate. Um, so are carbonate ions. I need to be greater than 6.82 times in the neck of six, divided by our point No. One for Moller from our concentration of my museum ions, that gives us 4.87 times 10 to the negative for Moeller. So the magnesium I owns air going to start precipitating when our carbonate concentration is 4.87 times 10 to the negative for Mueller. Um, so what is our iron concentration when we have that concentration of carbonate ions are so basically all we need to do is plug that carbonate concentration and the K s P of iron carbonate into, um into our equilibrium expression. And what we end up with is 6.3 times 10 to the negative eight Moeller for our iron ion concentration.