Calculate the concentration of all species in a 0.15 M KF solution.

Video transcript

Hey everyone, we're told that for a 2.50 molar sodium hypochlorite solution, what would be the concentration of the species present at equilibrium essentially. They wanted to find the concentration of each species. So we have our sodium hypochlorite and this is going to disassociate into sodium ions plus hypochlorite ions. And hypochlorite ion is the conjugate base of our hipaa Cloris acid. So for our reaction, we're going to have our hipaa chloride ion and we're going to react it with water. When these two react, we end up with hipaa Cloris acid plus our hydroxide ions creating our ice chart. We were told that we had 2.50 molar of our hypo chloride ion and we had zero of our products. Initially, our change is a minus X. For a hypochlorite ion since we're losing reactions and a plus X on our products since we're gaining products and we can go ahead and disregard our water since it is a liquid. And for our equilibrium we're going to have 2.50 minus X. For our reactant and an X. And an X. In our products. Looking up the K. A. Of Hipaa Cloris acid in our textbooks, We find that it's going to be 2.9 times 10 to the -8. And since Hipaa chloride ion is our conjugate base, we want to use our KB instead of the K. A. So far KB, it's going to be our K. W. Over R. K. A. Now plugging in our values, we have 1.0 times 10 to the -14. And we're going to divide this by 2.9 times 10 to the -8. This will get us to a kB of 3.4483 Times 10 to the -7. Now that we have our KB, let's go ahead and find our value for X. Now for our KB. We also know that its products over our reactant. So it's our X times are X over 2.50 minus X. We can go ahead and check if our X in the denominator is negligible And we can do this by taking our value of 2.50 And dividing it by RK. of 3.4483 times 10 to the -7. And we end up with a value greater than 500 which means we can disregard the X. and lead denominator. If it were a value less than 500 we would have to keep our X. In the denominator. Now let's go ahead and simplify this a bit further. So we had our KB which was 3.448, 3 times 10 to the -7. And this is going to be equivalent to x squared over 2.50. We want to eliminate our 2.50 and our denominator. So we're going to multiply both sides by 2.50. Then we want to take the square root of both sides. Right after. Once we do this we end up with an X. That is equivalent to 9.2848 times to the negative four moller. So this is going to be our value for our hydroxide ions and our hipaa Cloris acid. Lastly we can go ahead and find our concentration of hydro ni um ions. We know that our KW is equivalent to our hydro ni um ions times our hydroxide ions, solving for our hydro ni um ions. We get 1.00 times 10 to the -14 which is our KW. And we divide it by our concentration of hydroxide ions which is 9.28 4, 8 times 10 to the -4. And this will get us to a concentration of 1.08 Times 10 to the -11 Moller. So let's go ahead and write out our answers to this question. We had our concentration of our sodium ions which was equivalent to 2.50 moller. We had our concentration of our hypochlorite ion and it was 2.50 minus R. X. Which was 9.28 Times 10 to the negative for Mueller. And this came up to 2.50 moller as well. Next we had our concentration of hipaa Cloris acid and our hydroxide ions Which came up to 9. times 10 to the negative for Mueller. And lastly we had our concentration of our hydro knee um ions which came up to 1.8 times 10 to the negative 11 moller. And this is going to be our final answers. So I hope this made sense and let us know if you have any questions.