64) Use appropriate equations to account for the solubility of the amphoteric al
ID: 559538 • Letter: 6
Question
64) Use appropriate equations to account for the solubility of the amphoteric aluminum hydroxide [AlOH low and high pHs 456789 10 11 121 65) The following pictures represent solutions at various stages in the titration of a weak acid HzA with aqueous NaOH. (Na' ions and water molecules have been omitted for clarity,) «M o) (a) To which of the following stages do solutions 1-4 correspond? i) Halfway to the first equivalence point ii) II) At the first equivalence point ii) Halfway between the first and second equivalence points iv) Beyond the second equivalence point (b) Which solution has the highest pH? Which has the lowest pH? 66) Determine the pH of (a) a 0.40 M CH,COOH solution, (b) a solution that is 0.40 M C CH,COONa COOH and 0.20 M 67) Which of the following solutions can act as a buffer? (a) KCUHCI, (b) KHSOu/H SO4, (c) Na:HPOu/ NaH:PO4, (d) KNO,/HINO 68) .X, (molar mass-288 g) is 2.88 x 10 g/L. What is Ki for the 69) A volume of 75 mL of 0.060 M NaF is mixed with 25 mL of 0.15 M Sr(NOs). Calculate the concentrations in the final solution of NO,, Na', S, and F.(Kip for SrF:-2.0x 10) 70) Calculate whether or not a precipitate will form if 2.00 ml of 0.60 M NH, are added to 1.0L of 1.0x 10 M FeSO4 (Given that K.- 1NnJ (Nitiloin. 1.8 x 103 and K, [Fe(OH)21-1.6 × 10-14)Explanation / Answer
Q65
1)
solution 1 has mostly --> A-2 and HA-
therefore, this must be between equivalence point 1 and 2
from the list, it is the halfway between 1st and 2nd points, choose iii
2)
this is mostly H2A acid and HA-, which implies first buffer reagion
it is in the halfway of the 1st equivalence point, i)
3)
there ar eOH- and only A-2 present, this is excess OH- addition, since no more H+ is present
therefore, choose, beyond the 2nd equivalence point iv
4)
this has HA- alone
this must be in the 1st equivalence point, choose ii
b)
the highest pH --> by definition, OH- ions presence increase pH, choose 3
the lowest pH -- > must be the one with more H+ present, from the list, only 2) has most of it
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