From the value of Kf listed in Table 17.1, calculate the concentration of Ni2 +1aq2 and Ni1NH326 2+ that are present at equilibrium after dissolving 1.25 g NiCl2 in 100.0 mL of 0.20 M NH31aq2.

Video transcript

Hello, everyone in this video. We want to go ahead and solve for the modularity of CO2 plus as well as this complex ion here. So first I want to go ahead and write out my equation for c O Um BR two as well as the formation of our complex ion. So for our C O B R two, which is our cobalt two bro, might it's gonna go ahead and associate into its C 02 plus. KD on as well as two moles of our browning and ions. As for our formation of our complex ions, that's going to be one C 02 plus reacts with six moles of N H three to go ahead and form our C O N H 362 plus complex ion. So for our K. F value which we are given but we want to go ahead and bring it into its components of the concentration of our products over the concentration of our um starting reagents. So on top we will have the concentration of the complex ion Over the concentration of our CO2 plus and any coefficients. And the chemical reaction will be the power so we have six here. So now that would become our power of six on the K. F value equation. Of course we know that our care value is given to us. So this should equal to 1.30 times 10 to the fifth power. So keep putting this on the side for now I want to go ahead and do some dimensional analysis to get the mill arat E Of my C. O. B. R. Two. So I'll go ahead. Go ahead and do this in a different color. So starting off with the mass of C O. B. R two which is 1.75 g of C O. B. R. Two. I'm gonna go ahead and multiply this by its molar mass. So on the denominator I will have to 18.741 g. And on top I have one mole of cobalt to brew might. And then you can see that this gram unit will go ahead and cancel. So now that we have the moles of our C O. B. R. Two, I want to go ahead actually just for saving space wise to continue this mission analysis in regards to our leaders. So multiple that multiply this by mL. And we want to convert our male layers into leaders because we want that to be our unit for our malaria T. So one leader and mL. And we see that the male leader unit will go ahead and cancel leaving us with the moles of C. O. B. R. Two as well as leaders. So putting that into my calculator, I'll get 0.4 moller of C. O. B. R. Two or cobalt too bro might. We're gonna go ahead and assume that almost all of the cobalt to bromide will be converted into the complex ion. So The concentration of my c. 0 2 plus is going to be our unknown. Our concentration of our complex ion. What's rehearsal for is equal to 0.4 moller. And my concentration of her N. Age three is equal to 0.75 molar. Now going ahead to bring back that K. F. Equation right here, I'm basically going to go ahead and plug in my values now scroll down a little bit to give us a little bit more space. All right, so we have a K. F. Equaling to 1.30 times 10 to the fifth power equaling two. Well on top you have 0.4. And on the denominator we have X multiplied by 0.75 to the power of six. Of course we are solving for X here. So after some mathematical manipulation we get that the value of X is equal to when 0.04 is divided by while 1.3 times to the fifth power multiplied by 0.75 to the six power. And we can put all this into the calculator and get the numerical value of 1.7 to 88 times 10 to the negative six. We said that X is equal to the concentration of C. 02 plus and that is equal to 1.73. After running it to its appropriate significant figures. Ah So 1.73 times 10 to the negative six moller. So it's going to be one of my answers for this problem again scrolling down Now we can go ahead and solve for the concentration of our complex ion. So of CONH 3 to the power of six, so that's equal to n 0.4 subtracted by 1.7 to 88 times 10 to negative six. If we do the math here, every round to two decimal places will get 0. moller. And the reason that we use this extended values to eliminate any um error that we might have. So we can go ahead and use a bigger value or with more decimal places for more accuracy. And we can say then that the concentration of our complex ion Is equal to 0.04 Molar. And this is going to be my second and last answer for this problem again, we solve for the concentration of CO2 plus and the complex ion. Thank you all so much for watching