CHEM 211 Ch.17 smartbook

Which is the correct equation for the calculation of percent ionization of the weak acid HA in aqueous solution?

% ionization = [H+]eq/[HA]0× 100%

The pH of a salt solution containing a small, highly charged metal cation is influenced by the hydrolysis reaction of the metal ion. Which of the following statements correctly explain the hydrolysis reaction of these metal cations?

-A hydrated metal ion produces an acidic solution because the metal ion withdraws electron density from the O-H bond, facilitating loss of H+. -Small, highly charged metal cations accept electron pairs from water molecules and form hydrated ions.

Which of the following statements correctly describe the relationship between a weak acid or base and its conjugate base or acid?

-The weaker an acid is, the stronger its conjugate base will be. -The stronger a base is, the more strongly the formation of its conjugate acid is favored.

Which of the following solutions of HCN will have the greatest percent ionization?

0.00010 M

The [OH-] of a 0.010 M Ba(OH)2 solution is _____ M and the pOH is equal to _____.

0.020, 1.70 Reason: Ba(OH)2 is a strong base and produces 2 moles of OH- ions for each mole of Ba(OH)2. [OH-] = (0.010 mol x Ba(OH)2 / 1 L )x 2 mol OH^−1 / 1 mol Ba(OH)2 = 0.020 M

Rank the following carboxylic acids in order of increasing acid strength

1. CH3COOH 2.BrCH2COOH 3. CICH2COOH 4.Cl3CCOOH

Rank these bases in order of increasing strength, placing the strongest base at the bottom of the list.

1. Cl3CCOO-2. Cl2CHCOO-3. ClCH2COO-4. CH3COO-.

Arrange the following compounds in order of increasing acid strength (weakest at the top to strongest at the bottom of the list).

1. H2O 2. HF 3. HBr

Arrange the following acids in order of greatest (at the top of the list) to least (at the bottom of the list) amount of H3O+ produced in solution at a given concentration.

1. HClO2 2. HF 3. HClO 4. HCN

Rank the following 0.1 M salt solutions in order of increasing pH (lowest pH at the top of the list).

1. NaHSO4 2. NH4NO3 3. NaHCO3 4. Na2CO3

Which of the following types of substances are classified as acids only under the Lewis definition?

Molecules that contain a polar multiple bond Molecules with electron deficient central atoms

What is the conjugate base of HNO2 if it reacts as a Bronsted acid in H2O?

NO2-

Select all the compounds in the following list that are strong bases.

NaOH Ca(OH)2

An aqueous NaCl solution was found to have a pH = 7.00. Select all the statements that correctly describe this solution.

Neither Na+ nor Cl- reacts with water. The NaCl solution was neutral.

Which of the following species are Lewis acids?

SO3 Cu2+ BF3

Which of the hydrogens in chloroacetic acid is(are) considered acidic or ionizable?

The hydrogen bonded to oxygen Reason: In carboxylic acids, the ionizable proton is the one bonded to oxygen. Hydrogen atoms bonded to carbon do not ionize.

Calculate and compare the pH values for 0.10 M solutions of NH4Br (Ka 5.6 × 10-10) and Al(NO3)3 (Ka 1.3 × 10-5). Which of the following statements correctly describe the acidity of these solutions?

The pH of the Al(NO3)3 solution is 2.94. The NH4Br solution has a higher pH than the Al(NO3)3 solution.

A salt in which the anion is the conjugate _____ of a weak _____ will produce a basic solution

base, acid

A salt in which the anion is the conjugate _____ of a weak _____ will produce a basic solution. (Assume that the cation does not hydrolyze.)

base, acid reason; The conjugate base of a weak acid is itself a weak base. It will react with H2O to produce OH- ions and the resulting solution will be basic.

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

The strength of a weak base is indicated by its ______ ionization constant Kb. The greater the value of Kb, the _____ the base.

base; stronger

Like other metal hydroxides, amphoteric hydroxides react with strong acids to produce metal ions and water. However, amphoteric hydroxides also react with _____ to produce complex hydroxides bound to the metal ion.

bases

In a Bronsted-Lowry acid-base reaction, the acid reacts to form its _____ and the base will form its _____

conjugate base; conjugate acid

In an aqueous solution at a given temperature, the product [H3O+][OH-] has a _____ value. This product is equal to _____ at 25oC.

constant, 1.0 x 10-14

The product of a Lewis acid-base reaction contains a new bond called a _______ covalent bond.

coordinate

A Lewis acid-base reaction results in the donation of a pair of electrons from the base to the acid in the formation of a(n) _____ bond.

coordinate covalent

Given the ion-product constant for water Kw = [H3O+][OH-], as the concentration of hydronium increases the concentration of hydroxide _____.

decreases

A Bronsted-Lowry acid is a proton _____ and must therefore contain at least one ionizable _____ atom in its formula.

donor; hydrogen

An acid can be defined as a substance that loses one or more H+ ions when dissolved in water. An H+ ion is a hydrogen atom that has lost a(n) ________ and is therefore just a(n) _______. The H+ ion is not an isolated ion, but interacts strongly with H2O to produce the _______ ion, which has the formula H3O+.

electron; proton; hydronium

True or false: For any acid-base reaction, Ka x Kb = Kw for the reacting acid and base.

false; Reason: Correct. Ka x Kb = Kw only for a conjugate acid-base pair, not for any acid and base reacting.

The two types of strong acids are binary acids containing hydrogen bonded to a(n) _____ atom and oxoacids in which the number of O atoms exceeds the number of ionizable protons by _____ or more.

halogen; 2

The stronger the acid, the _____ the [H3O+] at equilibrium and the _____ the value of Ka.

higher; larger

Which of the following mathematical relationships are correct for an aqueous solution at 25°C?

pOH + pH = 14.00 pH = -log[H3O+]

The degree of ionization for a weak monoprotic acid HA is given by the expression [H+]eq[HA]0[H+]eq[HA]0 × 100%. This is called the _____ ionization and is a measure of acid strength.

percent

An acid-base reaction occurs when one species loses a(n) ______ and another species simultaneously _____a proton. An acid-base reaction can therefore be viewed as a proton- _______process.

proton; gains; transfer

Acid ionization 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

Hydrated _____ metal cations act as weak acids because these metal ions are so successful at withdrawing electron density from the O-H bond of water, thus facilitating the loss of H+ to the solvent water to form H3O+.

small, highly charged

The two factors that influence the extent of ionization of an acid are the ______ and _____ of the HX bond, where HX is the general formula of an acid.

strength; polarity

The two factors that influence the extent of ionization of an acid are the ______ and ______ of the HX bond, where HX is the general formula of an acid.

strength; polarity

The aqueous solutions of a strong acid and a weak acid are compared. Match each acid with the species that is/are present in the greatest concentration in the final solution. Note that the generic formula HA is used for each acid and A- for the conjugate base in both cases

strong acid: H3O+, A- weak acid: HA

In the reaction illustrated here, a proton is transferred from _____, which is the Bronsted _____, to _____, which acts as the Bronsted _____.

water, acid, ammonia, base reason: a proton is transferred from H2O

A(n) ______ acid is one that ionizes only slightly in water, whereas a(n) _______ acid ionizes completely.

weak;strong

In general, the stronger an acid is, the _____ its conjugate base will be. The stronger the acid, the more the equilibrium shown below will favor the formation of the _____. HA + H2O ⇌ H3O+ + A-

weaker, conjugate base Reason: The stronger the acid is, the more completely it ionizes in water. Its conjugate base reacts less strongly with water. Relatively speaking, the conjugate base is weaker in its acid-base behavior than the acid itself. The stronger the acid, the more the equilibrium will favor the formation of the conjugate base.

A 0.10 M solution of HCN (Ka = 4.9 × 10-10) is 7.0 × 10-3 % ionized. What is the pH of this solution?

5.15

Calculate the Kb value for the acetate ion (CH3COO-) if the Ka value for acetic acid (CH3COOH) is 1.8 x 10-5

5.6 × 10^-10 reason: Kb= 1.0 x 10^-14 / 1.8 x 10^-5

Which of the following statements correctly describe the acid-base properties of a 0.10-M solution of ammonium cyanide (NH4CN)? Select all that apply. Ka of NH4+ = 5.6 x 10-10 and Kb of CN- = 1.8 x 10-5.

Both NH4+ and CN- will hydrolyze (react with water) in aqueous solution. CN- will behave as a base when it reacts with water. The solution will be basic.

Which of the following statements correctly describe the relative strengths of acids and bases, and of conjugate acid-base pairs?

CH3COO- is a relatively stronger base than Cl3CCOO-. Iodide ion, the conjugate base of HI, is a weak base.

Water is an amphoteric species. Match the product formed from water acting as an acid or a base.

H3O+ = water is acting as a base OH-= water is acting as an acid

Match each acid correctly to the number of ionizable protons.

H3PO4=3 H2CO3=2 CH3COOH=1

Which of the following statements correctly explain the relative strengths of the oxoacids shown: HBrO < HClO < HClO2 < HClO3?

HBrO is weaker than HClO because Br is less electronegative than Cl. HClO3 is stronger than HClO2 because HClO3 has more O atoms.

Which of the following compounds are strong acids?

HI, H2SO4, HClO4

Match each species to the correct Lewis acid-base definition.

Lewis base: electron pair donor Lewis acid: electron pair acceptor

An amphoteric substance can behave as either a(n) ______ or a(n) ______.

acid or base

A salt consisting of a small, highly charged metal cation and the anion of a strong acid yields a(n) _____ solution.

acidic

A salt in which the cation is the conjugate acid of a weak base will be ______. (Assume that the anion does not hydrolyze.)

acidic

In general, nonmetal oxides tend to be _____ while metal oxides tend to be _____

acidic, basic

A salt consisting of the _____ of a strong acid and the _____ of a strong base yields a neutral solution.

anion; cation Reason: The conjugate base of a strong acid is an anion, not a cation.

Calculate the pH and [H3O+] of a 0.080 M solution of NaOH.

pH = 12.90 [H3O+] = 1.3 × 10-13 M

Rank the sequence of the steps you would use to calculate Kb starting with the pH of a weak base solution of known initial concentration.

1. Use pH to calculate POH 2. Calculate [OH-] from pOH 3. Use [OH-] and reaction stoichiometry to calculate equilibrium concentrations of HB+ and B 4. Use the equilibrium expression and calculate the value of Kb

Correctly order the steps necessary to solve weak-acid equilibrium problems, starting with the first step at the top of the list.

1. Write balanced equation and Ka expression2. Define x as the unknown change in concentration that occurs in the reaction and assume x is small compared to the [HA]Initial.3. Construct a reaction table that incorporates x, and solve for x by substituting values into the Ka expression.4. Check that the assumptions are justified by using 5% test. If not justified then use quadratic formula to solve for x.

A 0.32 M solution of phenol, which is a weak monoprotic acid, has a pH of 5.22. Place the steps required to calculate the value of Ka for phenol in the correct order.

1. [H3O+] = 10^5.22=6.03*10^-4 2. Assume that [phenol] = 0.323. . 3.Ka= (6.0310^-6)^2/(0.32) =1.1210^-104 4.% ionization = (6.0310^-6)/(0.32)100= 1.87*10^-3% so the assumption is justified 4.04

A 0.10 M CH3COOH solution has a [H3O+] = 1.3 × 10-3 M. What is the percent ionization of CH3COOH with a Ka = 1.8 × 10-5?

1.3%

A 0.15 M solution of butanoic acid, CH3CH2CH2COOH (or C3H7COOH), contains 1.51 × 10-3 M H3O+. What is the Ka of butanoic acid?

1.5 x 10^-5

What is the pH of a 0.25 M solution of ethanolamine (Kb = 3.2 × 10-5)?

11.45 Reason: [OH−]20.25[OH-]20.25 = 3.2 × 10-5. [OH-] = 0.25×3.2×10−5‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾√0.25×3.2×10-5 = 2.8 × 10-3 and [H3O+] = 1.0×10−142.8×10−31.0×10-142.8×10-3 = 3.57 × 10-12 pH = -log(3.57 × 10-12) = 11.45

Nitrous acid, HNO2, has a Ka of 7.1 × 10-4. What is the [H3O+] in a 0.60 M solution of HNO2?

2.1 × 10-2 M Reason: [H3O+] = [NO2-] = Ka×[HNO2]‾‾‾‾‾‾‾‾‾‾‾‾‾√2

Calculate the Ka value for the anilium ion (C6H5NH3+) if Kb for aniline (C6H5NH2) is 4.0 x 10-10

2.5 × 10^-5 reason; Ka = 1.0×10^−14/4.0×10^-10

When calculating the pH of a weak acid solution it is justified to assume that [H3O+] derived from the acid is negligible when the [H3O+] is less than _____% of the initial acid concentration.

5%

Match the relative concentrations of hydronium and hydroxide with the type of solution.

Acidic solution= [H3O+] > [OH-] Basic solution=[OH-] > [H3O+] Neutral solution=[H3O+] = [OH-]

Which of the following statements correctly describe amphoteric hydroxides?

Amphoteric hydroxides react with both acids and bases. Al(OH)3 is an amphoteric hydroxide.

Which of the following statements correctly describe carboxylic acids, represented by the general formula RCOOH?

As R changes, the strength of the acid changes. Carboxylic acids are organic acids represented by the general formula RCOOH. Carboxylic acids are weaker acids than hydrohalic acids such as HCl.

The product of a Lewis acid-base reaction is (CH3)2OBF3.

BF3 accepts an electron pair in this reaction. An empty 2p orbital on B accepts an electron pair from O.

Which of the following nonmetal oxides produce a weak acid when dissolved in water?

CO2 P4O10

Which of the following anions will produce a neutral solution in water?

Cl-, NO3-, I-

Which of the following oxides will NOT produce a basic solution in water?

Cl2O Reason: Group 17(7A) oxides (nonmetallic oxides) form acidic solutions in water. Cl2O + H2O → 2HClO (hypochlorous acid)

Which of the following options correctly describe the structural characteristics of strong and weak bases?

Compounds that contain electron-rich N are weak bases. Amines such as CH3CH2NH2 are weak bases. Soluble hydroxides are strong bases.

Finding the pH of a weak base solution is very similar to that for a weak acid. What is the only step that is necessary in the calculation of pH of a weak base and not a weak acid?

Convert [OH-] to [H3O+].

Which of the protons depicted in the structure of acetic acid is considered acidic or ionizable?

D; Reason: In carboxylic acids, the ionizable proton is the one bonded to oxygen. Hydrogen atoms bonded to carbon do not ionize.

Select all the reactions in which the Lewis acid is a cation and the Lewis base is a molecule with one or more lone pairs of electrons.

Fe3+ + 6H2O ⇌ Fe(H2O)63+ Ni2+ + 6NH3 ⇌ Ni(NH3)62+

Which of the following are valid assumptions used in solving weak-acid equilibrium problems?

For very weak acids (Ka < 10-4) at concentrations greater than 0.10 M, [HA]eqm ≈ [HA]0, the original acid concentration. The [H3O+] from water is negligible.

A compound that contains one or more ionizable ____ atoms as well as one or more available _____ electron pairs can act as either an acid or a base, depending on the reaction.

H ; non-bonding

Which of the following formulas can be used to represent a hydrogen ion in aqueous solution?

H+ H3O+

Which of the following statements correctly explains why even distilled and deionized H2O contains some ions?

H+ can be transferred from one H2O molecule to another, forming H3O+ and -OH ions.

The autoionization of water is a process where water ionizes very slightly to form _____ ions and _____ions.

H+; hydroxide or OH-

The hydrogen phosphate ion, HPO42-, can act as both a Bronsted acid and Bronsted base in water. Select all the options that correctly describe the reaction that occurs when HPO42- acts as a Bronsted base in water.

H2O acts as the Bronsted acid. OH- is one of the products. H2PO4- is one of the products.

Predict which of the following species would act as an amphoteric compound, that is, as both a Bronsted acid and a Bronsted base?

H2PO4- HCO3- H2O

Which of the following statements correctly describes the relative strength of binary acids?

H2S is a stronger acid than H2O.

Which of the following acids are polyprotic?

H2SO3 H3PO4

Which statement best explains the trend in acid strength: H2SO4 > H2SO3 > H2SeO3?

H2SO4 is stronger than H2SO3 because it has more O atoms.

Select all the statements that correctly describe the acid-base behavior of H2O.

In aqueous HCl, water acts as a Bronsted base. Water is amphoteric. In aqueous NH3, water acts as a Bronsted acid.

Determine if aqueous solutions of the following salts are acidic, basic, or neutral

KBr= neutral NH4I=acidic KCN= basic

Which of the following salt solutions will be basic, assuming that all have concentrations of 0.1 M?

KCH3COO NaCN

Match the correct qualitative prediction for a salt solution in which both its cation and anion hydrolyze.

Ka (of the salt's cation) > Kb (of the salt's anion) matches Choice, The salt solution is acidic. Ka (of the salt's cation) < Kb (of the salt's anion) matches Choice, The salt solution is basic. Ka (of the salt's cation) ≈ Kb (of the salt's anion) matches Choice, The salt solution is neutral.

Which of the following statements correctly describe the acid-base properties of a 1.0-M solution of methylammonium fluoride (CH3NH3F)? Select all that apply. Ka of HF = 7.1 × 10-4 and Kb of CH3NH2 = 4.4 × 10-4

Ka of CH3NH3+ = 2.3 × 10-11 Both CH3NH3+ and F- will hydrolyze (react with water) in aqueous solution. The solution will be slightly acidic because Ka of CH3NH3+ > Kb of F-.

Select all the expressions that correctly express the relationship between Ka and Kb for a conjugate acid-base pair.

Ka × Kb = Kw Ka = Kw/Kb

Which of the following correctly represents Kb for a weak base of general formula B?

Kb = [HB+][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+

Select all the statements that correctly describe the acid-base behavior of oxides.

Some metals from Group 13(3A) form amphoteric oxides. Most nonmetal oxides are acidic. Alkali metal oxides are basic.

Which of the following statements accurately describe Bronsted-Lowry acid-base reactions?

Some species can act as either an acid or a base depending on the other species present. The reactants and products contain an acid and a base.

If the pH of a 0.010 M solution of a strong base is 12.30, what is the identity of the base?

The base could be Ba(OH)2.

How does a conjugate acid differ from its conjugate base?

The conjugate acid has one more H than its conjugate base. The conjugate acid of a neutral base will have a charge of +1. A conjugate base may be positively charged, neutral, or negatively charged.

Which of the following factors will affect the relative strength of oxoacids?

The electronegativity of the central nonmetal atom The number of O atoms attached to the central nonmetal atom

Which of the following options correctly describe a solution with a pH = 8.00?

The solution is basic. [OH-] > [H3O+]

Which of the following options correctly describe the behavior of strong and weak acids (general formula HA) in aqueous solution?

The solution of a strong acid will have a negligible concentration of unionized HA molecules. A weak acid is a weak electrolyte.

Select all the options that correctly account for the behavior of NH4Cl in aqueous solution.

The solution will have a pH < 7.00. NH4+ + H2O ⇌ NH3 + H3O+

When calculating the pH of a weak acid or weak base solution, we assume that the [H3O+] or [OH-] due to ionization is negligible compared to the concentration of acid or base. When is this assumption justified?

When the acid/base shows less than 5% ionization

Which of the following options correctly describe the ionization constant Ka?

[H2O] is not included in the Ka expression for a particular acid. Reason: Although Ka = [H2O]Kc, [H2O] is not included in the Ka expression for a particular acid. Ka = [H3O+][A−][HA] Ka is the acid ionization constant.

Which of the following options correctly represent the relationship between [H3O+] and [OH-] in aqueous solutions at 25°C?

[H3O+] = 1.0×10^−14/[OH−] [H3O+][OH-] = 1.0 × 10-14

Which of the following gives the correct mathematical operation required to calculate the [H3O+] given a pH of 5.0?

[H3O+] = 10-5.0

Consider a 0.10 M CH3COOH solution (Ka = 1.8 x 10-5). Which statement is correct about this system at equilibrium?

[H3O+] = [CH3COO-]

A 0.10 M NH4Cl solution is found to be acidic. Select the statement that correctly represents the relative [H3O+] and [OH-] in this solution.

[OH-] < [H3O+]

Which of the following gives the correct mathematical operation required to calculate the concentration of hydroxide ions in a solution having a pOH of 9.38?

[OH-] = 10-9.38

Which statements are correct when calculating Kb of a 0.040 M NH3 solution with a pH = 10.93 at 25°C?

[OH-] may be calculated from pOH [NH4+]eq = [OH-]eq and [NH3]eq = [NH3]initial - [OH-]eq

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 ________ bond to H+.

acceptor; lone; electrons; covalent

A Lewis acid is any species that _____ an electron pair, whereas a Lewis base is a species that _____ an electron pair.

accepts; donates

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 ionization of the acid _____

increases

The strength of an acid is measured by its tendency to _______ and produce ______ ions in aqueous solution.

ionize; hydrogen

For solutions with the same initial concentration of acid HA, the smaller the value of Ka, the ______ the % ionization and thus the ______ the acid.

lower, weaker

When [H3O+] = [OH-], the solution is

neutral

Calculate the pH and [OH-] of a solution of a 1.5 M solution of HCl.

pH = -0.18 [OH-] = 6.7 × 10-15 M Reason: pH = -log (1.5) = -0.18. Although the pH values of many familiar solutions fall between 0 and 14, in reality pH values frequently fall outside this range. Reason: [OH-] = Kw/ [H3O+] = 1.0×10^−14/ 1.5