(2) Equilibrium Flashcards
(9NFC_1) At a concentration of 1 M, the weak acid HNO2 is 2% ionized and the pH of the solution is 1.7. What happens when KNO2(s) is dissolved into the solution?
(Increases/Decreases)
The extent of HNO2 ionization _____
The concentration of H+ _____
The pH _____
The extent of HNO2 ionization (decreases)
The concentration of H+ (decreases)
The pH (increases)
HNO2 H+ –> + NO2-
Adding KNO2 causes an increase of NO2- ions. Using Le Chatelier’s principle, reaction shifts to the left.
(9NFC_2) What is the iron (II) ion concentration in a solution prepared by mixing 445 mL of 0.417 M iron (II) nitrate with 425 mL of 0.364 M sodium hydroxide? The Ksp of iron (II) hydroxide is 7.9 × 10-16
0.124 M
Use ICE table for reaction Fe2+ + 2OH- –> Fe(OH)2. Hydroxide ion is the limiting reactant, so divide excess moles of Fe2+ by total volume.
(9NFC_3) What is the silver ion concentration in a solution prepared by mixing 403 mL of 0.357 M silver nitrate with 389 mL of 0.504 M sodium carbonate? The Ksp of silver carbonate is 8.1 × 10-127.
- 2 x 10^-6 M
http: //www.jiskha.com/display.cgi?id=1363044188
(9NFC_4) The Ksp of CaSO4 is 4.93× 10–5. Calculate the solubility (in g/L) of CaSO4(s) in 0.250 M Na2SO4(aq) at 25 °C.
0.0268 g/L
(9NFC_6) Which of the following will be more soluble in an acidic solution than in pure water? Select all that apply.
(A) Zn(OH)2 (B) RbClO4 (C) PbSO4 (D) CuCN (E) CuCl
(A), (C), (D)
(9NFC_7) For which of the following mixtures will Ag2SO4(s) precipiate? Select all that apply. Ksp for Ag2SO4(s) is 1.2 x 10^-5.
(A) 150.0 mL of 0.10 M Na2SO4(aq) and 5.0 mL of 0.20 M AgNO3(aq)
(B) 150.0 mL of 0.10 M Na2SO4(aq) and 5.0 mL of 0.30 M AgNO3(aq)
(C) 150.0 mL of 0.10 M Na2SO4(aq) and 5.0 mL of 0.40 M AgNO3(aq)
(D) 150.0 mL of 0.10 M Na2SO4(aq) and 5.0 mL of 0.50 M AgNO3(aq)
(C) 150.0 mL of 0.10 M Na2SO4(aq) and 5.0 mL of 0.40 M AgNO3(aq)
(D) 150.0 mL of 0.10 M Na2SO4(aq) and 5.0 mL of 0.50 M AgNO3(aq)
(9NFC_8) Sodium sulfate is slowly added to a solution containing 0.0500 M Ca2+(aq) and 0.0370 M Ag+(aq). What will be the concentration of Ca2+(aq) when Ag2SO4(s) begins to precipitate? What percentage of the Ca2+(aq) can be separated from the Ag+(aq) by selective precipitation? Ksp for Ag2SO4 is 1.20 x 10^-5. Ksp for CaSO4 is 4.93 x 10^-5.
[Ca2+] = 0.00562 M
88.8%
http://www.jiskha.com/display.cgi?id=1333744605
(9NFC_9) Suppose you have a solution that contains 0.0460 M Ca2+ and 0.0990 M Ag+. If solid Na3PO4 is added to this mixture, which of the following phosphate species would precipitate out first? Ksp for Ca3(PO4)2 = 2.07 x 10^-33. Ksp for Ag3PO4 = 8.89 x 10^-17
(A) Ca3(PO4)2 (B) Ag3PO4 (C) Na3PO4
When the second cation just starts to precipitate, what percentage of the first cation remains in solution?
(A) Ca3(PO4)2
13.6%
(9NFC_10) Assume an organic compound has a partition coefficient between water and diethyl ether equal to 7.07. If there are initially 7.37 grams of the compound dissolved in 80.0 mL of water, how many grams will remain in the aqueous layer after extraction with one 30.0 mL portion of ether?
- 02g
http: //answers.yahoo.com/question/index?qid=20130913183553AAnO06q
(9NFC_11) Which would be the more effective extraction route for a mixture of compounds X and Y: a single extraction using 75 mL of ether or combining the extracts from three separate extractions using 25 mL of ether?
(A) 1 x 75 mL (B) 3 x 25 mL (C) does not matter, they should be about equal
(B) 3 x 25 mL
(9NFC_12) You want to extract a solute from 100 mL of water using only 300 mL of ether. The partition coefficient between ether and water is 2.1. Calculate q, the fraction of solute that would remain in the water under each of the following extraction conditions:
(a) A single extraction with 300 mL of ether (b) Three extractions with 100 mL of ether (c) Six extractions with 50 mL of ether
(a) A single extraction with 300 mL of ether: 0.14
(b) Three extractions with 100 mL of ether: 0.034
(c) Six extractions with 50 mL of ether: 0.013
(9NFC_13a) A mixture of methyl orange, methyl red, and phenolphthalein are dissolved in an aqueous solution at pH = 8. A small volume of this solution is placed on an anion exchange column. The stationary phase is a polymer with fixed positively charged groups initially ion-paired with Cl- anions. Anions in the solution exchange with the Cl- anions, and thus are temporarily retained on the column.
Indicator | HA color | A- color | Ka
meth org red yellow 3.4 x 10^-4
meth red yellow red 7.9 x 10^-6
phenolpht colorless pink 4.0 x 10^-10
What colors do you predict for methyl orange and methyl red in a solution in which the pH is set independently at pH = 8? Phenolphthalein is colorless in this solution
Methyl orange is yellow. Methyl red is red.
(9NFC_13b) A mixture of methyl orange, methyl red, and phenolphthalein are dissolved in an aqueous solution at pH = 8. A small volume of this solution is placed on an anion exchange column. The stationary phase is a polymer with fixed positively charged groups initially ion-paired with Cl- anions. Anions in the solution exchange with the Cl- anions, and thus are temporarily retained on the column.
The equilibrium, Keq, between the polymer and the A- form of the indicator is:
polymer+Cl + A-(aq) polymer+A + Cl-(aq)
What happens as a concentrated solution of NaCl(aq) is poured down the column?
The equilibrium shifts to the left and the indicator moves down the column
(9NFC_13a) A mixture of methyl orange, methyl red, and phenolphthalein are dissolved in an aqueous solution at pH = 8. A small volume of this solution is placed on an anion exchange column. The stationary phase is a polymer with fixed positively charged groups initially ion-paired with Cl- anions. Anions in the solution exchange with the Cl- anions, and thus are temporarily retained on the column.
Indicator | HA color | A- color | Ka
meth org red yellow 3.4 x 10^-4
meth red yellow red 7.9 x 10^-6
phenolpht colorless pink 4.0 x 10^-10
For the equilibrium, Keq, between the indicators and the polymer shown above, which indicator is most predominantly retained by the stationary phase?
Methyl orange
(9NFC_19) Consider an amphoteric hydroxide, M(OH)2(s), where M is a generic metal.
M(OH)2(s) M2+(aq) + 2OH-(aq) Ksp = 8x10^-16
M(OH)2(s) + 2OH-(aq) M(OH)4(2-) Kf = 0.07
Estimate the solubility of M(OH)2 in a solution buffered at pH 7.0, 10.0, and 14.0
pH @ 7.0 = 0.08 M
pH @ 10.0 = 8 x 10^-8 M
pH @ 14 = 0.07 M
