13. (7 pts) A 50.0 mL sample of 0.180 M Fe(NO3)2 is added to 50.0 mL of 2.0 M NaCN. What is the
iron(II) ion concentration in this system at equilibrium?
. (6 pts) The measured pH of a saturated Ca(OH)2 solution is 12.35. Calculate the experimental value
for the Ksp of calcium hydroxide.
15.(12 pts) a) How many grams of solid ammonium chloride must be added to 250. mL of 0.500 M
aqueous ammonia to give a buffer with a pH of 9.40? (assume no change in volume)
b) If 2.00 mL of 3.00M nitric acid is added to 50.0 mL of the buffer prepared in part a), what will be the
pH of the resulting solution?
nigho diff 10 0 800.0 x
16. (12 pts) 20.0 mL of 0.120 M H2A, a weak acid, is titrated with 0.180 M NaOH.
a) The pH after adding 10.5 mL of base is 4.88. Calculate the experimental value of Ka, for H2A.
b) What is the pH at the second equivalence point? Kaz for H2A is 5.9 x 10-9.
17. (8 pts) A solution contains 0.25 M NaF and 0.14 M K2SO4. Ba(NO3)2 is added slowly to the solution
to gradually increase the concentration of barium ions.
a) You want to precipitate the maximum amount of sulfate (as BaSO4), but not allow any fluoride to
precipitate. What is the ideal [Baquot;] in the solution in order to accomplish this?
b) At the [Baquot;] you calculated for part a, what percentage of the original sulfate ion will remain in the
18. Sketch the titration curve for the titration of 40.0 mL of 0.120 M H2CO3 with 0.180 M KOH. Be sure
to clearly label any endpoints and be sure to show the volume of titrant is at these endpoints. Also,
indicate what the pH will be at any half-way point(s).