CHM142 Exam 3
greater
The closer the component concentrations are to each other, the ______the buffer capacity.
[Ag+]2[SO32-]
The expression for the solubility-product constant for silver sulfite, Ag2SO3, is
9.8 x 10^-8
The solubility of copper(II) iodate, Cu(IO3)2, is reported as 0.12 g per 100.0 mL of solution. What is the solubility product constant for this salt?
11.88
The values of pKa's for H3PO4 are pKa1=2.12, pKa2=7.21, and pKa3=12.38. Use the appropriate pKa to find the value of pKb for H2PO4-
greater
the greater the concentrations of the buffer components, the ______ the capacity to resist pH change
solubility
the maximum amount of solute that can be dissolved in a given quantity of a solvent at a specific temperature; usually given as the number of grams of solute in 1L of a saturated solution
molar solubility
the number of moles of solute in 1 L of a saturated solution
buffer range
the pH range over which a buffer acts effectively
end point
the point in a titration at which an indicator changes color
weaker
the stronger the acid is, the _____ is conjugate base
Co is the base, Ni is the acid
what are the lewis acid and lewis base in the equation 4CO + Ni --> Ni(CO)4
electronegativity and strength of bond
what does the acid strength of non-metal hydrides depend on?
electronegativity and number of O atoms
what does the acid strength of oxoacids depend on?
3.1 x 10^-10
what is the Kb of the 2-hydroxylammonium ion (pKb = 4.49)
1.59 x 10^-10
what is the Kb of the benzoate ion?
-0.00319
what is the change in entropy when 0.450mol of potassium freezes at 63.7 C (delta H = 2.39)
4.3
what is the correct concentration ratio of [CH3COO-]/[CH3COOH] of a buffer solution that has a pH of 5.37 (Ka = 1.8 x 10^-5)
5.76
what is the pH of 0.135M methylammonium bromide, Kb = 4.4x10^-4
8.38
what is the pH of 0.40M NaF
right
when an acid reacts with a fast that is further down the reactivity series, the reaction proceeds to the ____
strontium sulfate, calcium carbonate, barium iodate
which compound is more soluble in water? strontium sulfate/barium chromate copper(II) carbonate/calcium carbonate barium iodate/silver chromate
Fe(OH)3
which of the following will be more soluble in acid solution than in water? CuI PuCl2 Fe(OH)3 CaCO3
gibbs free energy
ΔG = ΔH - TΔS
slightly greater than % ionization in 0.10 M HNO2(aq).
The % ionization in 0.010 M HNO2(aq) must be
11.70
A 20.0 mL sample of a 2.00 x 10-2 M solution of nitrous acid, HNO2, is titrated with a 3.00 x 10-2 M solution of NaOH? What is the pH after 20.0 mL of NaOH solution have been added? Ka for HNO2 equals 4.5 x 10-4.
Ka2, 7.5
A buffer consists of 0.16M NaH2PO4 and 0.32M Na2HPO4. Phosphoric acid is a triprotic acid (Ka1 = 7.2 x 10^-3, Ka2 = 6.3 x 10^-8, Ka3 = 4.2 x 1-^-13). Which buffer is most important? What is the buffer pH?
10.20
A buffer is prepared by mixing 50.0mL of 0.050M sodium bicarbonate and 10.7ml of 0.10M NaOH (Ka = 4.7 x 10^-11)
4.92
A buffer solution contains 0.200 M CH3COOH and 0.250 M CH3COONa. What is the pH of the buffer solution after the addition of 10.0 mL of 0.100 M NaOH to 50.0 mL of the buffer? Ka for CH3COOH is equal to 1.8 x 10-5.
HI
A buffer solution could be formed when a solution of sodium acetate, (CH3)2COONa, is mixed with a solution of NH3 KOH. HI. CH3OH. NaCl.
9.18
A buffer that contains a 0.491M base, B, and 0.297M of its conjugate acid, BH+, has a pH of 9.14. What is the pH after 0.00200mol HCl is added to 0.250L of solution
entropy
A quantitative measure of disorder or randomness, symbolized by S.
acidic
A salt that consists of a small, highly charged metal cation and the anion of a strong acid yields an _____solution
basic
A salt that consists of the anion of a weak acid and the cation of a strong base yields a ___solution.
acidic
A salt that consists of the cation of a weak base and the anion of a strong acid yields a/an _____solution.
The OH- concentration will decrease and the Ca2+ concentration will increase
A saturated solution of calcium hydroxide, Ca(OH)2, is in contact with excess solid Ca(OH)2. Which of the following statements correctly describes what will happen when aqueous HCl (a strong acid) is added to this mixture, and system returns to equilibrium? (For Ca(OH)2, Ksp = 6.5 × 10-6) - The solubility of Ca(OH)2 will be unchanged. - The OH- concentration will decrease and the Ca2+ concentration will increase. - The OH- concentration will increase and the Ca2+ concentration will decrease. - The concentrations of both Ca2+ and OH- will increase. - The solubility of Ca(OH)2 will decrease.
0.075, 0.045, 0.015, 0.00012
A volume of 96 mL of 0.060M NaF is mixed with 32 MmL of 0.15M Sr(NO3)2. Calculate the concentrations of the following ions in the final solution (Ksp = 2.0 x 1-^-10) [NO3-] [Na+] [Sr2+] [F-]
slightly
Any "insoluble" ionic compound is actually ______soluble in aqueous solution
HBrO < HClO < HBr
Arrange the following acids HClO, HBrO, and HBr in order of increasing strength (weakest to strongest). HClO < HBrO < HBr HClO < HBr < HBrO HBrO < HBr < HClO HBrO < HClO < HBr HBr < HBrO < HClO
3 < 2 < 1
Arrange the following reactions according to increasing ∆Sº. 1: 2NH3(g) → N2(g) + 3H2(g) 2: N2O4(g) → 2NO2(g) 3: 2NO(g) + O2(g) → 2NO2(g)
1.3 x 10^-3M
At 25 ºC, the solubility-product constant (Ksp) for lead iodide, PbI2, is 8.5 x 10-9. What is the molar solubility of PbI2?
-268 kJ
At 25 ºC, ∆Gº=-141.7 kJ/mol for the following reaction 2SO2(g) + O2(g) → 2SO3(g) What is ∆Gº when 3.75 mol of SO3(g) is formed?
317.6
At 500.0 K ∆Sº for the reaction Cl2(g) + 3F2(g) → 2ClF3(g) is -265.1 J/(K· mol). If at the same temperature Sº(Cl2(g))=241.2 J/(K· mol) and Sº(F2(g))=219.7 J/(K· mol) what is the value of Sº of ClF3(g) at 500.0 K?
amphoterism
The ability of a substance to act as an acid and a base is known as
1.0 x 10^ -23
The acid ionization constant (Ka) for HI is estimated to be 1 x 109. What is the value of Kb for I-?
9.87
CCl4 has a normal freezing point of -22.92 ºC and at this temperature the molar enthalpy of fusion, ∆Hm,fus, is equal to 2.47 kJ/mol. Calculate the molar entropy of fusion (∆Sm,fus) of CCl4.
HONH2 (Kb = 1.1 x 10-8)
Consider 0.010 M aqueous solutions of five weak bases. Which solution will have the lowest pH? (CH3)2NH (Kb = 5.4 x 10-4) NH3 (Kb = 1.8 x 10-5) CH3NH2 (Kb = 4.4 x 10-4) (CH3)3N (Kb = 7.4 x 10-5) HONH2 (Kb = 1.1 x 10-8)
first law of thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed.
10.4
Find the pH of a buffer than consists of 0.34M CH3NH2 and 0.58M CH3NH3Cl (pKb of CH3NH2 = 3.35)
Ca(s) + Br2(l) + 3O2(g) → Ca(BrO3)2(s)
For which of the following reactions is ∆Gº equal to ∆Gfº of Ca(BrO3)2(s)? Ca(s) + 2Br(g) + 6O(g) → Ca(BrO3)2(s) Ca(s) + Br2(l) + 3O2(g) → Ca(BrO3)2(s) Ca(s) + Br2(g) + 3O2(g) → Ca(BrO3)2(s) Ca(g) + 2Br(g) + 6O(g) → Ca(BrO3)2(s) Ca(g) + Br2(g) + 3O2(g) → Ca(BrO3)2(s)
CaSO3(s) → CaO(s) + SO2(g)
For which of the following reactions is ∆Sº positive? Ca(s) + Cl2(g) → CaCl2(s) H2O(g) → H2O(l) O2(g) + 2SO2(g) → 2SO3(g) CO2(g) → CO2(s) CaSO3(s) → CaO(s) + SO2(g)
0.02418, 0.024, 4.1x10^-13
HF has a Ka of 6.8 x 10^-4. What are [H2O+], [F-] and [OH-]?
0.0131
In a 0.731M solution, a weak acid is 12.5% dissociated. Calculate Ka
0.040 M KCl
In which of the following aqueous solutions would you expect AgCl to have the lowest molar solubility? pure water 0.015 M MgCl2 0.025 M AgNO3 0.010 M FeCl3 0.040 M KCl
9.44
Instructions for making up a buffer solution say to mix 75.0 mL of a 0.125 M solution of ammonia, NH3, with 35.0 mL of a 0.175 M solution of ammonium chloride, NH4Cl. What is the pH of this solution? pKb of ammonia is 4.74.
0.0490
Lead nitrite is added slowly to a solution that is 0.0700M in Cl- ions. Calculate the concentration of pb2+ ions required to initiate the precipitation of PbCl2 (Ksp for PbCl2 is 2.40 x 10^-4)
ratio
Since Ka is constant, the [H3O+] of the solution depends on the ______ of buffer component concentrations
melting and vaporization at higher temperatures, dissolving of most soluble salts.
Spontaneous endothermic processes include:
freezing and condensation at low temperatures,combustion reactions, oxidation of iron and other metals.
Spontaneous exothermic processes include
-1356.9
Using the standard molar entropies of O2(g) [Sº= 205.1 J/(K·mol)], NH3(g) [Sº = 192.5 J/(K·mol)], N2(g) [Sº= 191.6 J/(K·mol)], and H2O(l) [Sº= 70.0 J/(K·mol)], and the values of ∆Hfº of NH3(g) (∆Hfº= -46.1 kJ/mol) and H2O(l) (∆Hfº= -285.8 kJ/mol), calculate the value of ∆Gº for the following reaction at 25.0 ºC. 4NH3(g) + 3O2(g) → 2N2(g) + 6H2O(l)
8.0 x 10^-7
What is the molar solubility of PbF2 in a 0.20 M solution of NaF? Ksp(PbF2) = 3.2 x 10-8
HPO42-(aq) + H3O+(aq) → H2PO4-(aq) + H2O(l)
What is the net ionic equation for the reaction that occurs when a small amount of hydrochloric acid is added to the Na2HPO4/NaH2PO4 buffer solution?
HCO3-(aq) + OH-(aq) → CO32-(aq) + H2O(l)
What is the net ionic equation for the reaction that occurs when a small amount of potassium hydroxide is added to the K2CO3/KHCO3 buffer solution?
11.97
What is the pH of 0.11M diethylamine where its Kb is 8.6x10^-4?
KCN/HCN, Na2SO4/NaHSO4
What solution can act as a buffer solution? KCN/HCN Na2SO4/NaHSO4 NH3/NH4NO3 NaI/HI
bromocresol green (Ka = 2.0 x 10-5)
Which of the following indicators is suitable for the titration of 0.10 M NH3 (Kb = 1.8 x 10-5) with 0.15 M HCl? thymol blue (Ka = 6.3 x 10-10) phenolpthalein (Ka = 4.0 x 10-10) cresol red (Ka = 3.5 x 10-9) bromocresol green (Ka = 2.0 x 10-5) bromothymol blue (Ka = 1.0 x 10-7)
SnO
Which of the following oxides is amphoteric? CaO FeO SO3 SnO CO2
NaNO2
Which of the following salts will form a basic solution in water? NH4Cl NaNO3 NaNO2 NaBr NaCl
CH3NH2(aq) + HBr(aq)
Which of the following titrations will result in a noticeably acidic solution at the equivalence point? HNO3(aq) + KOH(aq) CH3NH2(aq) + HBr(aq) HClO2(aq) + NaOH(aq) CH3COOH(aq) + LiOH(aq) KOH(aq) + HCl(aq)
ClO3-
Which one is the weakest base? BrO- BrO3- ClO- ClO3- ClO2-
NaNO2/HNO2 (Ka = 4.5 x 10-4)
Which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 3.20-3.40? NaOCl/HOCl (Ka = 3.2 x 10-8) CH3COONa/CH3COOH (Ka = 1.8 x 10-5) NaCl/HCl NH3/NH4Cl (Ka(NH4+) = 5.6 x 10-10 NaNO2/HNO2 (Ka = 4.5 x 10-4)
Yes, the ppt is AgBr(s)
Will a precipitate (ppt) form when 300.0 mL of 5.0 × 10-5M AgNO3 are added to 200.0 mL of 2.5 × 10-7M NaBr? Answer yes or no, and identify the precipitate if there is one.
Yes
Will a precipitate of BaF2 form when 50.0 mL of 6.2 x 10-2 M Ba(NO3)2 solution is added to 50.0 mL of 2.8 x 10-3 M NaF? Ksp(BaF2) = 1.8 x 10-7
negative, negative, negative
Without doing calculation, predict the sign of delta S for each of the reactions: H2S (g) + 0.5O2 --> 1/8S8 + H2O HCL + NaOH --> NaCl + H2O 2NO2 --> N2O4
common ion effect
a decrease in the solubility of an ionic compound caused by the addition of a common ion
neutral
a salt that consists of the cation of a strong base and the anion of the strong acid will yield a ____ solution
buffer solution
a solution that resists change in pH when small amount of acid or alkali is added
lewis acid
accepts electron pair
polyprotic acids
acids that contain more than one ionizable proton and release them sequentially
monoprotic acids
acids that contain one ionizable hydrogen
leveling effect
all strong acids and bases are equally strong in water
increases
as the initial concentration decreases, the percent dissociation of the acid
12.79, 10.90, 1.928
calculate the pH during the titration of 30.00ml of 0.1000M KOH and 0.1000M HBR solution after the following additions of acid: - 7.00ml - 29.50ml - 38.00ml
spontaneous change
change is one that occurs without a continuous input of energy from outside the system.
nonspontaneous
change occurs only if the surroundings continuously supply energy to the system.
9.1 x 10^-7
determine the Kb of a weak base of 0.23M solution if the base has a pH of 10.66 at 25 C
lewis base
donates electron pair
temperature, physical state, formation of a solution, atomic size, molecular complexity
factors that affect entropy
different
for oxoacids with ______ numbers of O atoms, acid strength increase with the number of O atoms
same
for oxoacids with the _____ number of O atoms, acid strength increases and electronegativity of E increases
1.0 x 10^-6
in very dilute solutions with concentrations below ______ the approximation should not be used
acidic
is Cr(NO3)3 acidic, basic or neutral?
basic
is NaHS acidic, basic or neutral?
acidic
is Zn(CH3COO)2 acidic, basic or neutral?
equivalence point
occurs when the moles of acid equal the moles of base in a solution
buffer capacity
the amount of acid or base a buffer solution can absorb without a significant change in pH
solubility product constant
the equilibrium constant for a solid that is in equilibrium with the solid's dissolved ions
standard molar gibbs energy of formation
the gibbs energy change for reaction in which one mol of a substance is formed from elements in their standard states
