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Chemistry
Q:
Which one of the following conditions is always true for a titration of a weak acid with a strong base?
A.A colored indicator with a pKa less than 7 should be used.
B.If a colored indicator is used, it must change color rapidly in the weak acid's buffer region.
C.Equal volumes of weak acid and strong base are required to reach the equivalence point.
D.The equivalence point occurs at a pH equal to 7.
E.The equivalence point occurs at a pH greater than 7.
Q:
Which of the following conditions is/are met at the equivalence point of the titration of a monoprotic weak base with a strong acid?
1/ The moles of acid added from the buret equals the initial moles of weak base.
2/ The volume of acid added from the buret must equal the volume of base titrated.
3/ The pH of the solution is less than 7.00.
A.1 only
B.2 only
C.3 only
D.1 and 3
E.2 and 3
Q:
A buffer contains 0.50 mol NH4+ and 0.50 mol NH3 diluted with water to 1.0 L. How many moles of NaOH are required to increase the pH of the buffer to 10.00? (pKa of NH4+ = 9.25)
A.0.035 mol
B.0.15 mol
C.0.35 mol
D.0.41 mol
E.2.8 mol
Q:
How many moles of HCl must be added to 1.0 L of 1.0 M NH3(aq) to make a buffer with a pH of 9.00? (pKa of NH4+ = 9.25)
A.0.36 mol
B.0.44 mol
C.0.56 mol
D.0.64 mol
E.1.8 mol
Q:
A buffer is composed of 0.400 mol H2PO4- and 0.400 mol HPO42- diluted with water to a volume of 1.00 L. The pH of the buffer is 7.210. How many moles of HCl must be added to decrease the pH to 6.210?A.0.200 molB.0.327 molC.0.360 molD.0.400 molE.3.60 mol
Q:
A buffer is prepared by combining 150 mL of 0.50 M NaOH and 250 mL of a 0.75 M weak acid, HA. If the pH of the buffer is 5.50, what is the Ka of the acid?A.1.3 10-11B.1.3 10-6C.2.1 10-9D.3.2 10-6E.4.7 10-6
Q:
The Ka of bicarbonate ion, HCO3-, is 4.8 10-11. What [CO32-]/[HCO3-] ratio is necessary to make a buffer with a pH of 11.00?A.0.21B.0.32C.0.68D.4.8E.6.8
Q:
If 0.50 L of a buffer containing 1.0 mol H2PO4- and 1.0 mol HPO42- is diluted to a volume of 5.0 L, the pH
A.increases by 1.
B.decreases by 1.
C.increases by 10.
D.decreases by 10.
E.remains unchanged.
Q:
If the ratio of acid to base in a buffer increases by a factor of 10, the pH of the buffer
A.increases by 1.
B.decreases by 1.
C.increases by 10.
D.decreases by 10.
E.remains unchanged.
Q:
What mass of solid NaCH3CO2 (molar mass = 82.0 g/mol) should be added to 1.0 L of 0.50 M CH3CO2H to make a buffer with a pH of 7.21? (pKa of CH3CO2H = 7.21)
A.0.0 g
B.1.9 g
C.41 g
D.71 g
E.1.6 102 g
Q:
What is the pH of a buffer that results when 0.40 mol NaHCO2 is mixed with 100.0 mL of 2.00 M HCl(aq) and diluted with water to 250 mL? (Ka of HCO2H = 1.8 10-4)A.-0.301B.3.05C.3.44D.3.74E.4.05
Q:
What is the pH of a buffer that results when 0.50 mole of H3PO4 is mixed with 0.75 mole of NaOH and diluted with water to 1.00 L? (The acid dissociation constants of phosphoric acid are Ka1 = 7.5 10-3, Ka2 = 6.2 10-8, and Ka3 = 3.6 10-13)A.1.82B.2.12C.6.91D.7.21E.12.44
Q:
What is the pH of a buffer that results when 0.50 mole of H3PO4 is mixed with 0.25 mole of NaOH and diluted with water to 1.00 L? (The acid dissociation constants of phosphoric acid are Ka1 = 7.5 10-3, Ka2 = 6.2 10-8, and Ka3 = 3.6 10-13)A.1.82B.2.12C.6.91D.7.21E.12.44
Q:
What is the pH of the buffer that results when 32 g sodium acetate (NaCH3CO2) is mixed with 500.0 mL of 1.0 M acetic acid (CH3CO2H) and diluted with water to 1.0 L? (Ka of CH3CO2H = 1.8 10-5)A.2.52B.4.23C.4.44D.4.64E.4.74
Q:
What is the pH of the buffer that results when 12.0 g of NaH2PO4 and 8.00 g of Na2HPO4 are diluted with water to a volume of 0.50 L? (Ka of H2PO4- = 6.2 10-8, the molar masses of NaH2PO4 and Na2HPO4 are 120.0 g/mol and 142.0 mol, respectively)A.4.10B.6.96C.7.21D.7.46E.9.90
Q:
What is the pH of a buffer composed of 0.35 M H2PO4-(aq) and 0.65 M HPO42-(aq)? (Ka of H2PO4- is 6.2 10-8)A.6.94B.7.21C.7.48D.7.73E.9.06
Q:
Which of the following mathematical expressions is the Henderson-Hasselbalch equation?
A.
B.
C.
D.
E.
Q:
All of the following statements concerning acid-base buffers are true EXCEPT
A.buffers are resistant to pH changes upon addition of small quantities of strong acids or bases.
B.buffers are used as colored indicators in acid-base titrations.
C.the pH of a buffer is close to the pKa of the weak acid from which it is made.
D.buffers contain appreciable quantities of a weak acid and its conjugate base.
E.buffers are resistant to changes in pH when diluted with water.
Q:
When mixed in appropriate amounts, each of the following mixtures can produce an effective buffer solution EXCEPT
A.HCl and NaH2PO4
B.Na2HPO4 and Na3PO4.
C.NaHCO3 and Na2CO3.
D.NaH2PO4 and Na2HPO4.
E.NaOH and NaF.
Q:
Which of the following combinations would be best to buffer an aqueous solution at a pH of 9.0?A.H3PO4 and H2PO4-, Ka1 = 7.5 10-3B.HNO2 and NO2-, Ka = 4.5 10-4C.CH3CO2H and CH3COO-, Ka = 1.8 10-5D.H2PO4- and HPO42-, Ka2 = 6.2 10-8E.NH4+ and NH3, Ka = 5.7 10-10
Q:
Which of the following combinations would be best to buffer an aqueous solution at a pH of 7.0?A.H3PO4 and H2PO4-, Ka1 = 7.5 10-3B.HNO2 and NO2-, Ka = 4.5 10-4C.CH3CO2H and CH3COO-, Ka = 1.8 10-5D.H2PO4- and HPO42-, Ka2 = 6.2 10-8E.NH4+ and NH3, Ka = 5.7 10-10
Q:
What is the pH of an aqueous solution composed of 0.64 M NH4+ and 0.20 M NH3? (Ka of NH4+ = 5.6 10-10)A.4.80B.8.75C.9.20D.9.25E.9.76
Q:
What is the pH of a solution that results from adding 250 mL of 0.50 M NaOH to 750 mL of 0.50 M HF? (Ka of HF = 7.2 10-4)A.1.87B.2.84C.3.44D.3.62E.6.29
Q:
What is the pH of a solution that results from adding 150.0 mL of 0.200 M HCl to 150.0 mL of 0.350 M NH3? (Kb of NH3 = 1.8 10-5)A.9.01B.9.13C.9.26D.9.50E.10.01
Q:
What is the pH of a solution that results from diluting 0.30 mol acetic acid (CH3CO2H) and 0.20 mol sodium acetate (NaCH3CO2) with water to a volume of 1.0 L? (Ka of CH3CO2H = 1.8 10-5)A.4.35B.4.57C.4.74D.4.92E.5.14
Q:
What is the effect of adding NaOH(aq) to an aqueous solution of ammonia?
1/ The pH of the solution will increase.
2/ The concentration of NH4+(aq) will decrease.
3/ The concentration of NH3(aq) will increase.
A.1 only
B.2 only
C.3 only
D.2 and 3
E.1, 2, and 3
Q:
An acid-base equilibrium system is created by dissolving 0.50 mol CH3CO2H in water to a volume of 1.0 L. What is the effect of adding 0.50 mol CH3CO2-(aq) to this solution?1/ The pH of the solution will equal 7.00 because equal concentrations of a weak acid and its conjugate base are present.2/ Some CH3CO2H(aq) will ionize, increasing the concentration of CH3CO2-(aq) and increasing the pH.3/ Some CH3CO2-(aq) will react with H3O+, increasing the concentration of CH3CO2H(aq) and reestablishing the solution equilibrium.A.1 onlyB.2 onlyC.3 onlyD.1 and 3E.1, 2, and 3
Q:
Which is the stronger Brnsted-Lowry acid, Fe(H2O)62+ or Fe(H2O)63+?Explain.
Q:
Write a net ionic equation for the neutralization reaction of hydrochloric acid and potassium hydroxide. Identify the spectator ion(s).
Q:
The chemical equations below show the reaction of Al(OH)3 as a Lewis acid and as a Lewis base, respectively.Al(OH)3(s) + OH-(aq) Al(OH)4-(aq)Al(OH)3(s) + 3 H3O+(aq) Al3+(aq) + 3 H2O()Substances that can behave as either Lewis acids or bases are called ________ substances.
Q:
When a Lewis acid combines with a Lewis base, the base supplies both electrons to the bond. This type of chemical bond is called a(n) ________ covalent bond.
Q:
A molecule that can behave as either a Brnsted-Lowry acid or base is termed ________.
Q:
When a Lewis acid and a Lewis base combine, the product may be referred to as an acid-base ________.
Q:
All of the following species behave as Lewis acids EXCEPT ____.
A.BH3
B.Al3+
C.SO2
D.Al(OH)3
E.NH3
Q:
Identify from the following list of molecules and ions which behave as Lewis acids: CO2, NH3, BCl3, Fe3+.
A.CO2 and NH3
B.NH3 and BCl3
C.CO2 and Fe3+
D.CO2, BCl3, and Fe3+
E.CO2, NH3, BCl3, and Fe3+
Q:
Which of the following molecules or ions is the strongest acid?
A.CH3CO2"
B.CH3CO2H
C.CFH2CO2H
D.CF2HCO2H
E.CF3CO2H
Q:
All of the following compounds are acids containing chlorine. Which compound is the weakest acid?
A.HCl
B.HClO
C.HClO2
D.HClO3
E.HClO4
Q:
Which of the following statements is INCORRECT?
A.H3PO4 is a stronger acid than H2PO4-.
B.HClO3 is a stronger acid than HClO2.
C.HNO3 is a stronger acid than HNO2.
D.[Fe(H2O)6]2+ is a stronger acid than [Fe(H2O)6]3+.
E.HOCl is stronger acid than HOBr.
Q:
Which of the following species is the strongest acid in an aqueous solution?
A.CH3CH2CO2H
B.CH2ClCO2H
C.CH3CO2H
D.CCl3CO2H
E.CHCl2CO2H
Q:
What is the pH of 1.0 M Na2SO3(aq) at 25 C? (Ka1 = 1.2 10-2, Ka2 = 6.2 10-8)A.3.40B.6.03C.7.96D.10.40E.10.60
Q:
Which of the following chemical equations corresponds to Kb1 for SO32-?A.HSO3-(aq) + H2O() H2SO3(aq) + OH-(aq)B.SO32-(aq) + H3O+(aq) HSO3-(aq) + H2O()C.H2SO3(aq) + OH-(aq) HSO3-(aq) + H2O()D.HSO3-(aq) + OH-(aq) SO32-(aq) + H2O()E.SO32-(aq) + H2O() HSO3-(aq) + OH-(aq)
Q:
Which of the following chemical equations corresponds to Ka3 of phosphoric acid?A.HPO42-(aq) + H2O() PO43-(aq) + H3O+(aq)B.PO43-(aq) + H2O() HPO42-(aq) + OH-(aq)C.H3PO4(aq) + H2O() H2PO4-(aq) + H3O+(aq)D.H3PO4(aq) + 2 H2O() HPO42-(aq) + 2 H3O+(aq)E.H2PO4-(aq) + H2O() HPO42-(aq) + H3O+(aq)
Q:
What is the pH of the solution which results from mixing 75 mL of 0.50 M NH3(aq) and 75 mL of 0.50 HCl(aq) at 25 C? (Kb for NH3 = 1.8 10-5)A.0.60B.2.67C.4.74D.4.93E.9.26
Q:
What is the pH of the solution which results from mixing 50.0 mL of 0.30 M HF(aq) and 50.0 mL of 0.30 M NaOH(aq) at 25 C? (Ka of HF = 7.2 10-4)A.1.98B.5.84C.8.16D.10.85E.12.02
Q:
The pH of aqueous 0.50 M hypobromous acid, HBrO, is 4.45. What is the Ka of this acid?A.2.5 10-9B.5.0 10-9C.3.4 10-7D.3.5 10-5E.7.1 10-5
Q:
The pH of aqueous 0.10 M pyridine (C5H5N) ion is 9.09. What is the Kb of this base?A.8.0 10-10B.1.5 10-9C.9.0 10-6D.1.6 10-5E.1.2 10-5
Q:
What is the pH of 0.010 M aqueous hypochlorous acid? (Ka of HOCl = 3.5 10-8)A.2.00B.4.50C.4.73D.6.54E.7.45
Q:
What is the pH of 0.50 M aqueous ethylamine? (Kb of C2H5NH2 = 4.3 10-4)A.1.84B.3.37C.10.33D.10.63E.12.16
Q:
What is the pH of 0.25 M aqueous acetate ion? (Kb of CH3CO2- = 5.6 10-10)A.4.32B.4.93C.9.07D.9.68E.13.40
Q:
What is the pH of 0.30 M aqueous formic acid? (Ka of HCO2H = 1.8 10-4)A.0.52B.1.61C.2.14D.3.74E.4.24
Q:
What is the OH- concentration in 0.48 M CH3CO2-(aq)? (Kb of CH3CO2- = 5.6 10-10)A.2.7 10-10 MB.6.2 10-10 MC.1.1 10-5 MD.1.6 10-5 ME.2.4 10-5 M
Q:
What is the H3O+ concentration in 0.50 M HOCl(aq)? (Ka of HOCl = 3.5 10-8)A.1.8 10-8 MB.3.5 10-8 MC.2.9 10-7 MD.1.3 10-4 ME.5.0 10-1 M
Q:
Given the following equilibrium constants,Ka (HSO4-) = 1.2 10-2Kb (CH3CO2-) = 5.6 10-10Kw = 1.00 10-14determine the equilibrium constant for the reaction below at 25 C.HSO4-(aq) + CH3CO2-(aq) SO42-(aq) + CH3CO2H(aq)A.6.7 10-12B.2.1 10-7C.1.5 10-3D.6.7 102E.2.1 107
Q:
Given the following acid dissociation constants,Ka (H3PO4) = 7.5 10-3Ka (NH4+) = 5.6 10-10determine the equilibrium constant for the reaction below at 25 C.H3PO4(aq) + NH3(aq) NH4+(aq) + H2PO4-(aq)A.4.2 10-12B.7.5 10-8C.4.2 102D.1.3 107E.2.4 1011
Q:
What is the equilibrium constant for the following reaction at 25 C.HCl(aq) + KOH(aq) H2O() + KCl(aq)A.1.00 10-14B.1.00 10-7C.1.00D.1.00 10+7E.1.00 10+14
Q:
What is the equilibrium constant for the following reaction,HCO2H(aq) + CN-(aq) HCO2-(aq) + HCN(aq)and does the reaction favor the formation of reactants or products? The acid dissociation constant, Ka, for HCO2H is 1.8 10-4 and the acid dissociation constant for HCN is 4.0 10-10.A.K = 1.00. The reaction favors neither the formation of reactants nor products.B.K = 2.2 10-6. The reaction favors the formation of products.C.K = 2.2 10-6. The reaction favors the formation of reactants.D.K = 4.5 105. The reaction favors the formation of products.E.K = 4.5 105. The reaction favors the formation of reactants.
Q:
Which ionic compound forms a pH-neutral aqueous solution at 25 C?
A.NaHCO3
B.LiClO4
C.LiF
D.NH4Cl
E.K2S
Q:
At 25 C, all of the following ions produce an acidic solution, except ____.A.NH4+B.HSO3-C.HPO42-D.[Fe(H2O)6]3+E.[Al(H2O)6]3+
Q:
At 25 C, all of the following ionic compounds produce a basic aqueous solution, except ____.
A.NaF
B.Na3PO4
C.NaNO2
D.NaHSO4
E.NaCH3CO2
Q:
Hydrofluoric acid has a pKa value of 3.14. What is the value of pKb for fluoride ion?A.1.4 10-11B.7.2 10-4C.3.14D.10.86E.17.14
Q:
Which of the following weak acids has the strongest conjugate base in an aqueous solution?A.formic acid (HCO2H), Ka = 1.8 10-4B.hypobromous (HOBr), Ka = 2.5 10-9C.hydrogen sulfite ion (HSO3-), Ka = 6.2 10-8D.nitrous acid (HNO2), Ka = 4.5 10-4E.phosphoric acid (H3PO4), Ka = 7.5 10-3
Q:
If 0.10 M aqueous solutions are prepared of each of the following acids, which produces the solution with the lowest pH?A.benzoic acid, Ka = 6.3 10-5B.acetic acid, Ka = 1.8 10-5C.hydrocyanic acid (HCN), Ka = 4.0 10-10D.hydrogen sulfite ion (HSO3-), Ka = 6.2 10-8E.hypobromous (HOBr), Ka = 2.5 10-9
Q:
Which of the following chemical equations corresponds to the base ionization constant, Kb, for hydrogen sulfite ion (HSO3-)?A.HSO3-(aq) + H2SO3(aq) 2 H2SO3(aq)B.HSO3-(aq) + H2O() SO32-(aq) + H3O+(aq)C.HSO3-(aq) + OH-(aq) SO32-(aq) + H2O()D.HSO3-(aq) + H3O+(aq) H2SO3(aq) + H2O()E.HSO3-(aq) + H2O() H2SO3(aq) + OH-(aq)
Q:
Which of the following chemical equations corresponds to the acid ionization constant, Ka, for benzoic acid (C6H5CO2H)?A.C6H5CO2-(aq) + H3O+(aq) C6H5CO2H(aq) + H2O()B.C6H5CO2H(aq) + H2O() C6H5CO2-(aq) + H3O+(aq)C.C6H5CO2H(aq) + OH-(aq) C6H5CO2-(aq) + H2O()D.C6H5CO2H(aq) + H3O+(aq) C6H5CO2H2+(aq) + H2O()E.C6H5CO2-(aq) + H2O() C6H5CO2H(aq) + OH-(aq)
Q:
An aqueous solution with a pH of 10.60 is diluted from 1.0 L to 2.0 L. What is the pH of the diluted solution?
A.5.30
B.9.60
C.10.30
D.10.60
E.10.90
Q:
An aqueous solution with a pH of 2.00 is diluted from 1.0 L to 3.0 L. What is the pH of the diluted solution?
A.0.67
B.2.00
C.2.48
D.4.33
E.6.00
Q:
What is the OH- concentration of an aqueous solution with a pH of 9.83? (Kw = 1.01 10-14)A.1.3 10-10 MB.6.8 10-5 MC.6.8 10-1 MD.1.5 10-2 ME.7.4 109 M
Q:
What is the OH- concentration of an aqueous solution with a pH of 2.77? (Kw = 1.01 10-14)A.5.9 10-12 MB.1.7 10-3 MC.5.2 10-2 MD.1.1 101 ME.5.9 102 M
Q:
What is the H3O+ concentration of an aqueous solution with a pH of 8.77?A.1.7 10-9 MB.5.9 10-6 MC.1.6 10-4 MD.5.23 ME.5.9 108 M
Q:
What is the pH of 6.5 10-5 M KOH(aq) at 25 C? (Kw = 1.01 10-14)A.-4.19B.1.54C.4.19D.9.81E.12.46
Q:
What is the pH of 0.75 M HCl(aq) at 25 C? (Kw = 1.01 10-14)A.-0.12B.0.12C.0.75D.2.75E.13.87
Q:
Which one of the following aqueous solutions will have a pH of 2.00 at 25 C? (Kw = 1.01 10-14)A.0.020 M HNO3B.2.0 M NaOHC.10.0 M HBrD.10.0 M KClE.0.010 M HCl
Q:
What is the H3O+ concentration in 7.1 10-3 M NaOH(aq) at 25 C? (Kw = 1.01 10-14)A.7.2 10-17 MB.1.4 10-12 MC.2.9 10-3 MD.12 ME.7.0 1011 M
Q:
A solution is prepared by diluting 0.055 mol HNO3 with water to a volume of 1.75 L. What is the pH of the solution?
A.-1.50
B.0.031
C.1.26
D.1.50
E.12.50
Q:
At 50 C, the water ionization constant, Kw, is 5.48 10-14. What is the H3O+ concentration in neutral water at this temperature?A.3.00 10-27 MB.2.74 10-14 MC.5.48 10-14 MD.2.34 10-7 ME.1.01 10-7 M
Q:
Which of the following molecules or ions is amphiprotic in water?A.NH4+B.F-C.CH3CO2HD.HC2O4-E.CO32-
Q:
Which is NOT an amphiprotic species in water?A.HClO3B.HSO3-C.H3O+D.HS-E.HCO3-
Q:
Molecules or ions that can alternately behave as either a Brnsted-Lowry acid or base are called
A.polyanions.
B.hydronium ions.
C.polyprotic acids or bases.
D.conjugate acids or bases.
E.amphiprotic.
Q:
The conjugate base of HPO42- is ____.A.OH-B.PO43-C.H2PO4-D.H2OE.H3O+
Q:
What is the conjugate base of [Fe(H2O)6]3+(aq)?
A.H3O+
B.[Fe(H2O)6]2+
C.[Fe(H2O)5H3O]4+
D.[Fe(H2O)5OH]2+
E.[Fe(H2O)5]3+