CH 18 Smart book
Which of the following species usually act as weak bases? Select all that apply.
PO43- CH3NH2 CH3COO-
______ metal ions are acidic in aqueous solution because their hydrated form can transfer an H+ to water.
Small, highly charged
Which of the following solutions of HCN will have the greatest percent dissociation?
0.00010 M
A Bronsted-Lowry acid is a proton _____ and must therefore contain at least one ionizable _____ atom in its formula.
donor; hydrogen
In a Bronsted-Lowry acid-base reaction, equilibrium will favor the _____ if the reacting acid and base are strong. The reaction will always favor the formation of the _____ acid and base.
products; weaker
A salt consisting of the anion of a _____ acid and the cation of a _____ base yields an acidic solution.
strong; weak
The direction of an acid-base equilibrium depends on the relative strengths of the acids and bases involved. Since strong acids and strong bases readily accept and donate protons, the equilibrium will always favor the reaction of the _____ acid and base and the formation of the _____ acid and base.
stronger; weaker
A(n) acid is one that dissociates only slightly in water, whereas a(n) acid dissociates completely into ions.
weak strong
True or false: For any acid-base reaction, Ka x Kb = Kw for the reacting acid and base.
f
What is the Ka of an acid if a 0.500 M solution contains 1.70 x 10-4 M H3O+?
5.8 x 10-8
How does a conjugate acid differ from its conjugate base? Select all that apply.
A conjugate base may be positively charged, neutral, or negatively charged. The conjugate acid of a neutral base will have a charge of +1. The conjugate acid has one more H than its conjugate base.
Which of the following species is present in the greatest concentration in a 1.0 M solution of CH3COOH?
CH3COOH
All strong acids and bases appear equally strong in H2O. This is because in water the strongest acid possible is , while the strongest base possible is . In both cases the equilibrium favors the dissociation products, and water is said to exert a effect on any strong acid or base.
H3O+ OH- leveling
The pH of a solution is a measure of its _____ concentration.
H3O+ ion
A particular salt contains both an acidic cation and a basic anion. If the Ka of the cation is greater than the Kb of the anion, a solution of the salt will be ______. If the Ka of the cation is less than the Kb of the anion, a solution of the salt will be ______.
acidic; basic
A salt consisting of the _____ of a strong acid and the _____ of a strong base yields a neutral solution.
anion; cation
Select all the statements that correctly describe the aqueous solution of a metal cation.
A solution containing small, highly charged metal cations will be acidic. A metal cation can withdraw electron density from the O-H bonds of H2O molecules, releasing H+ ions.
A 0.15 M solution of butanoic acid, CH3CH2CH2COOH, contains 1.51 x 10-3 M H3O+. What is the Ka of butanoic acid?
1.5 x 10-5
Which of the options given expresses the solution to the following calculation to the correct number of significant figures? pH = -log(1.12 x 10-12)
11.951
Nitrous acid, HNO2, has a Ka of 7.1 x 10-4. What is the [H3O+] in a 0.60 M solution of HNO2?
2.1 x 10-2 M
Which of the following statements correctly describes the behavior of strong acids, HA, in aqueous solution?
A strong acid dissociates completely into ions in water. [H3O+] = [A-] ≈ [HA]init Strong acid molecules are not present in aqueous solutions.
Which of the following statements describe the behavior of strong and weak acids (general formula HA) in aqueous solution? Select all that apply.
A weak acid is a weak electrolyte. The solution of a strong acid will have extremely few to no undissociated HA molecules.
Which of the following statements does NOT describe a type of weak acid?
All hydrohalic acids in Period 3 or below
Select all the compounds in the following list that are strong bases.
CaO NaOH
Which of the following anions will produce a neutral solution in water? Select all that apply, and assume that any associated cations do not affect the pH.
I- NO3- Cl-
Which of the following options correctly describe the constant Ka? Select all that apply.
[H2O] is not included in the Ka expression for a particular acid. Ka is the acid-dissociation constant.
Calculate the pH and [H3O+] of a 0.080 M solution of NaOH.
[H3O+] = 1.3 x 10-13 M pH = 12.90
Oxoacids have the general formula illustrated, where the number of bonds to the central element E can vary. For the same element E, acid strength will _____ as the number of O atoms increases. For the same number of O atoms, acid strength increases as the _____ of element E increases.
increase; electronegativity
As the initial concentration of a weak acid decreases, the percent dissociation of the acid _____.
increases
Which of the following monoprotic acids would give a solution with the lowest pH at the same molarity?
HSO4- (pKa = 1.99)
Which of the following factors will affect the relative strength of oxoacids? Select all that apply.
The electronegativity of the central nonmetal atom The number of O atoms attached to the central nonmetal atom
The strength of a weak base is indicated by its -ionization constant Kb. The greater the value of Kb, the the base.
base stronger
The quantity -log[H3O+] is called the of a solution.
pH
Acid dissociation is represented by the general equation HA + H2O (l) ⇌ H3O+ (aq) + A- (aq). For a strong acid the equilibrium lies far to the _____ and [H3O+] is much _____ than [HA]. For a weak acid, on the other hand, the equilibrium lies far to the _____ and [H3O+] is much _____ than [HA].
right; higher; left; lower
HCN has a Ka value of 6.3 x 10-10 while acetic acid has a Ka value of 1.8 x 10-5. HCN is a _____ acid than acetic acid and will therefore have a _____ pKa value.
weaker; higher
H2S is a _____ acid than HCl because S is _____ electronegative than Cl, while HBr is a _____ acid than HCl because the H-Cl bond is shorter and has _____ strength than the H-Br bond.
weaker; less; stronger; greater
An acid has a Ka of 1.34 × 10-6. What is the pH of a 0.509 M solution?
3.08
Which of the following options correctly describe the structural characteristics of strong and weak bases? Select all that apply.
Amines such as CH3CH2NH2 are weak bases. Compounds that contain electron-rich N are weak bases. Soluble hydroxides are strong bases.
Select ALL the weak acids from the following list.
HF HCN CH3CH2COOH
In order to determine the overall acidity of a 0.1 M solution of NaHCO3, the and values for HCO3- must be compared. Ignore the use of any superscripts or subscripts in your answers.
Ka Kb
Select all the expressions that correctly express the relationship between Ka and Kb for a conjugate acid-base pair.
Ka x Kb = Kw Ka = KwKb
Which of the following expressions correctly represents Kb for a weak base of general formula B?
Kb = [BH+][OH−][B]
In order to determine whether a solution of NH4C2H3O2 is acidic, basic, or neutral, what two values could be compared?
Kb of CH3COO- Ka of NH4+
The two general types of weak base include molecules that contain one or more atoms and the conjugate bases of weak .
N acids
Select ALL the strong bases from the following list.
Na2O LiOH Ca(OH)2
Which one of the following 0.1 M salt solutions will be basic?
NaCN
Which of the following compounds can be classified as bases according to the Arrhenius definition? Select all that apply.
NaOH Ba(OH)2
Select the correct statements describing a solution containing a salt composed of the cation of a strong base and the anion of a polyprotic acid. Select all that apply.
The anion will hydrolyze to produce either H3O+ or OH- ions depending on the relative values of Ka and Kb of the anion. The cation has no impact on the pH of the solution.
Which of the following statements correctly describe a 1.0 M solution of KCN? Select all that apply.
The solution is basic. The solution contains a significant concentration of the weak base CN-.
Select all the factors that affect the ease with which a proton is released from a nonmetal hydride (represented by the general formula E-H.)
The strength of the E-H bond The electronegativity of the central atom (E)
Select the correct descriptions of the leveling (limiting) effect of water on strong acids and strong bases. Select all that apply.
The strongest acid in an aqueous solution is the hydronium ion. A strong acid will cease to exist in aqueous solutions because water will readily accept its proton to form hydronium ions.
A Bronsted-Lowry base is a proton . A Bronsted-Lowry base must contain an available pair of in its formula in order to form a(n) bond to H+.
acceptor lone electrons sigma
A salt consisting of the anion of a weak _____ and the cation of a strong _____ yields a basic solution.
acid; base
A salt consisting of a small, highly charged metal cation and the anion of a strong acid yields a(n) _____ solution.
acidic
An acid donates a proton to form its conjugate , which therefore has one less atom and one more charge than its acid.
base H negative
Given the ion-product constant for water Kw = [H3O+][OH-], as the concentration of hydronium increases the concentration of hydroxide _____.
decreases
The stronger the acid, the _____ the [H3O+] at equilibrium and the _____ the value of Ka.
higher; larger
Since pK = -logK, a low pK value corresponds to a _____ K value. A strong acid will have a _____ Ka value and a _____ pKa value.
large; large; low
For solutions with the same initial concentration of acid HA, the smaller the value of Ka, the _____ the % dissociation and thus the _____ the acid.
lower; weaker
The pH of a solution is a logarithmic value. This means that ______.
only digits after the decimal point are significant
Calculate the pH and [OH-] of a solution of a 1.5 M solution of HCl.
pH = -0.18 [OH-] = 6.7 x 10-15 M
