Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

Group Problem 1. There is a solution of a mixture of the following: AgNO3, Hg2 i

ID: 1041835 • Letter: G

Question

Group Problem 1. There is a solution of a mixture of the following: AgNO3, Hg2 ions, and Pb(NOs)2. The -10. -18 concentration of each of the metal ions in solution is 0.050 M and a volume of 0.250 L, give the order in which the metal ions will precipitate out by adding 1.00 M HCI. What volume of HCl is needed to precipitate the first ion? 2. One of the buffers to maintain the pH of blood is the carbonic acid, H2CO3, buffer. Carboni acid is diprotic and it's equilibrium constants are Ka1 4.2x107 and Ka2 4.8x 1011. How would your prepare 5.0 L a carbonic acid buffer of a pH of 7.2 from 0.250 M H2COs? You have available NaHCOs (MW 84.0) and Na2COs (MW- 106). Hint: First decide which acid-base pair to use.

Explanation / Answer

Solution:

1.

i) Precipitating order

First AgCl

second Hg2Cl2

Third PbCl2

ii) AgCl(s) <-----> Ag+(aq) + Cl-(aq)

Ksp = [Ag+][Cl-] = 1.6×10^-10

when [ Ag+ ] = 0.050

0.050M × [Cl-] =1.6×10^-10M^2

[ Cl- ] = 3.2×10^-9M= 3.2×10^-9mole/L

No of mole HCl required for 250ml = 8.0×10^-8mol

Therefore,

Volume of the 1M solution required = (1000ml/1M)×8.0×10^-8 = 0.00008m