CHEM 2 UNIT EXAM 3

Formula for [OH-] *when given pH

14.00 = pH + pOH

What is Ka of a weak acid HX if a 0.303 M solution of HX has a pH of 2.341?

6.97x10-5

Which of the following salts yields an acidic solution in water? A. NaNO3 B. KBr C. LiF D. AlCl3 E. NaI

AlCl3 is an acidic salt because of the acidic cation Al3+.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

What is the pH of a 9.5x10-4 M aqueous solution of Ba(OH)2?

Ba(OH)2 is a strong base. By definition, strong indicates that the base completely dissociates in water.Ba(OH)2 Ba2+ + OH- Because Ba(OH)2 is a strong base and there is a one to two mole ratio between Ba(OH)2 and OH- 1.9x10-3 M OH- pH = 14.00 + log[OH-] = 14.00 + log(1.9x10-3) = 11.28

Which of the following salts yields a neutral solution in water? A. CuCl2 B. NH4NO3 C. BaCl2 D. Na2CO3 E. NaCN

BaCl2 is a neutral salt because neither the cation or the anion undergoes any significant hydrolysis.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

For which of the following is the equilibrium constant called the "Kb of CN-"? CN-(aq) + H3O+(aq) <=> HCN(aq) + H2O(l) HCN(aq) + H2O(l) <=> CN-(aq) + H3O+(aq) HCN(aq) + OH-(aq) <=> CN-(aq) + H2O(l) CN-(aq) + H2O(l) <=> HCN(aq) + OH-(aq) HCN(aq) + H3O+(aq) <=> CN-(aq) + H4O2+(aq)

CN-(aq) + H2O(l) HCN(aq) + OH-(aq) Kb is the equilibrium constant for a weak base. It is the equilibrium involved when a weak base is added to water. This is also referred to as hydrolysis. The reaction is written with the base reacting with H2O giving the products of the conjugate acid of the base and OH-.

For which of the following is the equilibrium constant called the "Kb of CO32-"? HCO3-(aq) + H2O(l) <=> CO32-(aq) + H3O+(aq) CO32-(aq) + H2O(l) <=> HCO3-(aq) + OH-(aq) H2CO3(aq) + H2O(l) <=> H3O+(aq) + HCO3-(aq) HCO3-(aq) + H2O(l) <=> H2CO3(aq) + OH-(aq) CO32-(aq) + H3O+(aq) <=> HCO3-(aq) + H2O(l)

CO32-(aq) + H2O(l) HCO3-(aq) + OH-(aq) Kb is the equilibrium constant for a weak base. It is the equilibrium involved when a weak base is added to water. This is also referred to as hydrolysis. The reaction is written with the base reacting with H2O giving the products of the conjugate acid of the base and OH-.

What is the concentration of OH- in a 3.55x10-3 M aqueous solution of Ca(OH)2?

Ca(OH)2 is a strong base. By definition, strong indicates that the base completely dissociates in water.Ca(OH)2 Ca2+ + 2OH- Because Ca(OH)2 is a strong base and there is a one to two mole ratio between Ca(OH)2 and OH- 7.10x10-3 M OH-

For which of the following is the equilibrium constant called the "Ka of H2CO3"? HCO3-(aq) + H2O(l) <=> CO32-(aq) + H3O+(aq) CO32-(aq) + H2O(l) <=> HCO3-(aq) + OH-(aq) H2CO3(aq) + H2O(l) <=> H3O+(aq) + HCO3-(aq) HCO3-(aq) + H2O(l) <=> H2CO3(aq) + OH-(aq) H2CO3(aq) + H3O+(aq) <=> H3CO3+(aq) + H2O(l)

H2CO3(aq) + H2O(l) <=> H3O+(aq) + HCO3-(aq) Ka is the equilibrium constant for a weak acid. It is the equilibrium involved when a weak acid is added to water. This is also referred to as hydrolysis. The reaction is written with the acid reacting with H2O giving the products of the conjugate base of the acid and H3O+.

Consider the following reaction: NH4+(aq) + H2O(l) NH3(aq) + H3O+(aq)which occurs when ammonium chloride (NH4Cl) is dissolved in water. The Bronsted-Lowry base for the forward reaction is

H2O is accepting a proton in the forward reaction; therefore is a Bronsted-Lowry base.The Bronsted-Lowry model considers that an acid is a proton donor and a base is a proton acceptor.

For which of the following is the equilibrium constant called the "Kb of H2PO4-"? HPO42-(aq) + H2O(l) <=> PO43-(aq) + H3O+(aq) PO43-(aq) + H2O(l) <=> HPO42-(aq) + OH-(aq) H3PO4(aq) + H2O(l) <=> H2PO4-(aq) + H3O+(aq) HPO42-(aq) + H2O(l) <=> H2PO4-(aq) + OH-(aq) H2PO4-(aq) + H2O(l) <=> H3PO4(aq) + OH-(aq)

H2PO4-(aq) + H2O(l) <=> H3PO4(aq) + OH-(aq) Kb is the equilibrium constant for a weak base. It is the equilibrium involved when a weak base is added to water. This is also referred to as hydrolysis. The reaction is written with the base reacting with H2O giving the products of the conjugate acid of the base and OH-.

State whether H2SO4 is a strong or weak acid.

H2SO4 is a strong acid.You must learn the strong acids to be able to determine what is strong and what is weak. The strong acids are HCl, HBr, HI, HClO4, H2SO4, and HNO3.

What is the pH of a 6.8x10-3 M aqueous solution of HBr?

HBr is a strong acid. By definition, strong indicates that the acid completely ionizes in water.HBr + H2O H3O+ + Br-Because HBr is a strong acid and there is a one to one mole ratio between HBr and H3O+, [H3O+] = [HBr] = 6.8x10-3 M therefore, pH = -log[H3O+] = -log(6.8x10-3) = 2.17

Consider the following reaction:CN-(aq) + H2O(l) HCN(aq) + OH-(aq)which occurs when potassium cyanide (KCN) is dissolved in water. The Bronsted-Lowry acid for the reverse reaction is

HCN The species you selected is donating a proton in the reverse reaction; therefore is a Bronsted-Lowry acid.The Bronsted-Lowry model considers that an acid is a proton donor and a base is a proton acceptor.

For which of the following is the equilibrium constant called the "Ka of HCN"?

HCN(aq) + H2O(l) <=> CN-(aq) + H3O+(aq) Ka is the equilibrium constant for a weak acid. It is the equilibrium involved when a weak acid is added to water. This is also referred to as hydrolysis. The reaction is written with the acid reacting with H2O giving the products of the conjugate base of the acid and H3O+.

Which of the following is the conjugate base of H2CO3?

HCO3- The Bronsted-Lowry model considers that an acid is a proton donor and a base is a proton acceptor.The species formed when a proton is removed from an acid is referred to as the conjugate base of that acid, i.e. B- is the conjugate base of HB. The species formed when a proton is added to a base is called the conjugate acid of that base, i.e. HA is the conjugate acid of A-.

What is the concentration of H3O+ in a 4.47x10-4 M aqueous solution of HCl?

HCl is a strong acid. By definition, strong indicates that the acid completely ionizes in water.HCl + H2O H3O+ + Cl-Because HCl is a strong acid and there is a one to one mole ratio between HCl and H3O+, [H3O+] = [HCl] = 4.47x10-4 M .

What is the concentration of H3O+ in a 1.15x10-2 M aqueous solution of HClO4?

HClO4 is a strong acid. By definition, strong indicates that the acid completely ionizes in water.HClO4 + H2O H3O+ + ClO4-Because HClO4 is a strong acid and there is a one to one mole ratio between HClO4 and H3O+, [H3O+] = [HClO4] = 1.15x10-2 M

What is the pH of a 5.8x10-2 M aqueous solution of HNO3?

HNO3 is a strong acid. By definition, strong indicates that the acid completely ionizes in water.HNO3 + H2O H3O+ + NO3-Because HNO3 is a strong acid and there is a one to one mole ratio between HNO3 and H3O+, [H3O+] = [HNO3] = 5.8x10-2 M therefore, pH = -log[H3O+] = -log(5.8x10-2) = 1.24

For which of the following is the equilibrium constant called the "Ka of HPO42-"? HPO42-(aq) + H2O(l) <=> PO43-(aq) + H3O+(aq) PO43-(aq) + H2O(l) <=> HPO42-(aq) + OH-(aq) H3PO4(aq) + H2O(l) <=> H2PO4-(aq) + H3O+(aq) HPO42-(aq) + H2O(l) <=> H2PO4-(aq) + OH-(aq) H2PO4-(aq) + H2O(l) <=> HPO42-(aq) + H3O+(aq)

HPO42-(aq) + H2O(l) PO43-(aq) + H3O+(aq) Ka is the equilibrium constant for a weak acid. It is the equilibrium involved when a weak acid is added to water. This is also referred to as hydrolysis. The reaction is written with the acid reacting with H2O giving the products of the conjugate base of the acid and H3O+.

Which of the following is the conjugate base of H2SO4?

HSO4- The Bronsted-Lowry model considers that an acid is a proton donor and a base is a proton acceptor.The species formed when a proton is removed from an acid is referred to as the conjugate base of that acid, i.e. B- is the conjugate base of HB. The species formed when a proton is added to a base is called the conjugate acid of that base, i.e. HA is the conjugate acid of A-.

Which of the following salts yields an acidic solution in water? A. KClO4 B. Cr(NO3)3 C. K3PO4 D. LiNO3 E. CdCl2

K3PO4 is a basic salt because of the basic anion PO43-.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

Which of the following salts yields a neutral solution in water? A. KBr B. Zn(NO3)2 C. Al(NO3)3 D. NaCN E. KC2H3O2

KBr is a neutral salt because neither the cation or the anion undergoes any significant hydrolysis.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

What is the pH of a 1.3x10-1 M aqueous solution of KOH?

KOH is a strong base. By definition, strong indicates that the base completely dissociates in water.KOH K+ + OH- Because KOH is a strong base and there is a one to one mole ratio between KOH and OH- 1.3x10-1 M OH- pH = 14.00 + log[OH-] = 14.00 + log(1.3x10-1) = 13.11

Formula for [OH-] *when given [H3O+]

Kw = [H3O+][OH-] = 1.00 x 10^-14 @25C

Which of the following salts yields an acidic solution in water? A. K3PO4 B. KI C. CaBr2 D. NH4Cl E. Na2CO3

NH4Cl is an acidic salt because of the acidic cation NH4+.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

Which of the following salts yields a basic solution in water? A. Na2CO3 B. NaBr C. ZnCl2 D. NH4Cl E. KNO3

Na2CO3 is a basic salt because of the basic anion CO32-.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

Which of the following salts yields a basic solution in water? A. NaNO3 B. KCl C. NaCN D. Zn(NO3)2 E. Ca(NO3)2

NaCN is a basic salt because of the basic anion CN-.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

What is the concentration of OH- in a 2.00x10-2 M aqueous solution of NaOH?

NaOH is a strong base. By definition, strong indicates that the base completely dissociates in water.NaOH Na+ + OH- Because NaOH is a strong base and there is a one to one mole ratio between NaOH and OH- 2.00x10-2 M OH-

State whether NaOH is a strong or weak base.

NaOH is a strong base.You must learn the strong bases to be able to determine what is strong and what is weak. The strong bases are LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2.

conjugate acid, conjugate base

The Bronsted-Lowry model considers that an acid is a proton donor and a base is a proton acceptor.The species formed when a proton is removed from an acid is referred to as the conjugate base of that acid, i.e. B- is the conjugate base of HB. The species formed when a proton is added to a base is called the conjugate acid of that base, i.e. HA is the conjugate acid of A-.

conjugate base, conjugate acid

The Bronsted-Lowry model considers that an acid is a proton donor and a base is a proton acceptor.The species formed when a proton is removed from an acid is referred to as the conjugate base of that acid, i.e. B- is the conjugate base of HB. The species formed when a proton is added to a base is called the conjugate acid of that base, i.e. HA is the conjugate acid of A-.

Which of the following salts yields an acidic solution in water? A. Zn(NO3)2 B. NaCN C. KCl D. NaNO3 E. Ca(NO3)2

Zn(NO3)2 is an acidic salt because of the acidic cation Zn2+.You must examine the ions associated with a soluble salt for possible hydrolysis to determine if the salt solution will be acidic, basic, or neutral. Cations undergo hydrolysis and produce hydronium ions (acidic) except Group I and II metals. Anions undergo hydrolysis and produce hydroxide ions (basic) except the conjugate base of a strong acid.

Which of the following is the Arrhenius definition of an acid?

a substance that yields H+ or H3O+ in water

For the following pair of acids: acid 1: H2CO3acid 2: HCO3- which is the stronger acid?

acid 1

For the following pair of acids: acid 1: HFacid 2: H2O which is the stronger acid?

acid 1 Going across a row of elements, the electronegativity increase, the H-X bond polarity increases, and the acid strength increases.

For the following pair of acids: acid 1: H2Sacid 2: H2O which is the stronger acid?

acid 1 In going down a column of elements, the size of atom X increase, the H-X bond strength decreases, and the strength of the binary acid increases.

For the following pair of acids: acid 1: HNO2acid 2: HNO3 which is the stronger acid?

acid 2 For a series of oxoacids, the acid strength increases with the number of O atoms bonded to Y.

For the following pair of acids: acid 1: HBrO4acid 2: HClO4 which is the stronger acid?

acid 2 oxoacids of the same structure (H-O-Y-), differing only in the atom Y, has acid strength increasing with electronegativity of Y

Which of the following is the Lewis definition of an acid?

an ion or molecule that accepts a pair of electrons as it forms a coordinate covalent bond with another ion or molecule.

Which of the following is the Bronsted-Lowry definition of an acid?

an ion or molecule that donates a proton to another ion or molecule

Formula for finding pOH *when given [OH-]

pH = - log10[H+]

Formula for finding the pH of an ion *when given [H3O+]

pH = - log10[H+] = - log10[H3O+]

Formula for [H3O+] *when given pH

pH = - log10[H+] = - log10[H3O+] [H3O+] = [H+] = 10-pH

Formula for finding pH of an ion *when given just [OH-]

pH = 14.00 + log[OH-]