You have to prepare a pH = 5.00 buffer, and you have the following 0.10 M solutions available: HCOOH, HCOONa, CH3COOH, CH3COONa, HCN, and NaCN. How many milliliters of each solution would you use to make approximately 1 L of the buffer?

Video transcript

Hey everyone. So here we have a student that needs prepared buffer of ph five and she chooses to meth opera phenolic acids Which has a PK of 4.84. And she also has 0.1 molar of two month opera pandemic solution and 0.12 Mahler of sodium two meta probe on a weight solution. Or asked how much volume and male leaders Does she need to prepare a total of ml of her buffer. So we're gonna use our handle Stonehouse about equation which is ph it was P. K. A. Plus the law the concentration of the conjugate base. What about the concentration of the weak acid? And we need to find the volume of the acid in the volume of the base. So we're giving ph and PK A. We're gonna have five. It was 4.84. Plus the law SCB guarded by W. A. If you subtract 4.84 from both sides, We're going to get 0.16 equal to the log other ratio, We're going to do 10, It is 0.16 power. And it's going to be equal to the concentration. And this will give us 1.44 by four. So now we can use the equation. M. A thomas B. A. It was M. B times VP. And we have the concentrations of each but we don't have the volume of the acid or the base. We're gonna have 0.1 times be a Equal to 0.12 tom Vp. So here we have two variables and the solution in total has 50 mL. So we're going to be A plus B. B. Equal to 50. So B. B Equals 50 -7. A. So now we can substitute this for VP. So we're going to get 0.1 times be A Equals 0.12 times 50 minus V. A. And this, it's gonna be a concentration that can't you get based and this it's gonna be a contradiction of the weak acid. So we can divide these two instead of equal to 1.4454. So we're going to get 0.12 times 50 minus V. A Divided by 0. times be a Equal to 1. by four. So now we must have both sides 0.1 times V. A. We're gonna get 0.12 times 50 minus V. A. Equal to 0.1 or four times be A. So we're going to get six 10.12. Come to be a. It was 0.144 times be a. Sophie adds 0.12 B. A. On both sides. We're going to get six Equals 0. 454 B. A. And now we divide by 0.264 54. The V A. Going to get 22 .7 male leaders and B. B. 50 minus V. A. We're gonna get 50 minus 22 0.7. Would you give us 27.3 male leaders? So for two metals proper know it, We're gonna have 22 0.7 male leaders. And for sodium to metal proper, No. Eight. We're gonna get 27.3 male leaders. Thanks for watching my video. And I hope it was helpful.