CH-132 exam 3

Describe the relationship between molecular structure and acid strength. Check all that apply. 1.The stronger the bond between a hydrogen atom and its neighbor, the weaker the acid. 2.The weaker the bond between a hydrogen atom and its neighbor, the weaker the acid. 3.The more electron-withdrawing atoms near the hydrogen atom, the weaker the bond to the hydrogen and the weaker the acid will be. 4.The more electron-withdrawing atoms near a hydrogen atom, the weaker the bond to the hydrogen and th

1&4

What is the concentration of hydroxide ions in pure water at 30.0°C, if Kw at this temperature is 1.47 × 10-14? 1.21 × 10-7 M 1.00 × 10-7 M 1.30 × 10-7 M 1.47 × 10-7 M 8.93 × 10-8 M

1.21 × 10-7 M

Which one of the following statements is TRUE? A buffer is an aqueous solution composed of two weak bases. A buffer can absorb an unlimited amount of acid. A buffer resists pH change by neutralizing added acids and bases. A buffer does not change pH when strong acid is added. None of the above are true.

A buffer resists pH change by neutralizing added acids and bases.

Describe a molecule that can be a Lewis acid.

A molecule with an incomplete octet can serve as a Lewis acid.

Which of the following solutions is a good buffer system? A solution that is 0.10 M HCN and 0.10 M LiCN A solution that is 0.10 M NaCl and 0.10 M HCl A solution that is 0.10 M K and 0.10 M HNO3 A solution that is 0.10 M K OH and 0.10 M HNO3 A solution that is 0.10 M HCN and 0.10 M K Br

A solution that is 0.10 M HCN and 0.10 M LiCN

What is the difference between a strong and a weak acid?

A strong acid completely ionizes in solution, whereas a weak acid only partially ionizes in solution.

What does the term amphoteric mean?

A substance that can act as both an acid and a base, depending on what it is reacting with

Which of the following could be added to a solution of sodium acetate to produce a buffer? A. acetic acid B. sodium hydroxide C. sodium chloride D. potassium acetate

A. acetic acid

Which of the following is TRUE?

An acidic solution has [H3O+] > [OH-]

A Bronsted-Lowry acid is defined as a substance that ________. A. Acts as a proton acceptor B. Acts as a proton donor C. Increases [H+] when placed in H2O D. Accepts a pair of electrons

B. Acts as a proton donor

Which of the following compounds is a Lewis Acid, but not a Brønsted-Lowry acid? A. NH3 B. Fe3+ C.H3O+ D.OH-

B. Fe3+

In the forward reaction, which substance acts as the Brønsted-Lowry base? HSO4-(aq)+NH3(aq) —><— SO4^2-(aq)+NH4^+(aq) A. HSO4- B. NH3 C. SO4^2- D. NH4^+

B. NH3

Which of the following describes an acidic solution? A. pOH=7 B. [H3O+]>[OH-] C. [H3O+]=1.0x10^-8 M D. [H3O+]<[OH-]

B. [H3O+]>[OH-]

Which of the following is a Lewis acid?

BCl3

Define buffer capacity

Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness.

Which of the following is the strongest base? A. CH3COO- (Kb=5.6x10^-10) B. ClO- (Kb=3.3x10^-7) C. CN- (Kb=2.0x10^-5) D. NO2- (Kb=2.2x10^-11)

C. CN- (Kb=2.0x10^-5)

Classify the following compounds as weak acids (W) or strong acids (S). HClO4, HCOOH, HF A. WSS B. WSW C. SWW D. SWS

C. SWW

Which one of the following salts, when dissolved in water, produces the solution with the highest pH? NaClO4 NaHSO3 LiF Na3PO4 CaO

CaO

Which of the following is the weakest acid? A. HClO B. HClO2 C. HBr D. HBrO

D. HBrO

The Bronsted-Lowry model focuses on the transfer of _______ in an acid-base reaction.

H+

Identify the diprotic acid.

H2SO3

What is the conjugate acid of HSO3- ?

H2SO3

Identify the strong diprotic acid.

H2SO4

Which of the following is a polyprotic acid? H2SO4 HF LiCN CH4 HC2H3O2

H2SO4

Which of the following is an Arrhenius acid?

H2SO4

Identify the products when hydrochloric acid completely ionizes in water.

H3O+ and Cl−

Identify the triprotic acid.

H3PO4

Which of the following solutions would have the highest pH? Assume that they are all 0.10 M in acid at 25∘C. The acid is followed by its Ka value. HClO2, 1.1 × 10-2 HOCl, 2.9 × 10-8 HNO2, 4.6 × 10-4 HCHO2, 1.8 × 10-4 HC6H5O, 1.3 × 10-10

HC6H5O, 1.3 × 10-10

Which of the following acids will have the strongest conjugate base?

HCN

Which of the following is a strong acid?

HCl

Identify the weak monoprotic acid.

HF

Identify the strongest acid. HBr HCl HI HF

HI

Which Bronsted-Lowry acid is NOT considered to be a strong acid in water?

HNO2

Which of the following is an Arrhenius base?

LiOH

Which of the following is a Bronsted-Lowry base?

NH3

Identify the products that are in equilibrium with NH3NH3 and H2O

NH4+ and −OH

Which of the following is NOT a conjugate acid-base pair?

NH4+/NH2-

Which one of the following will form an acidic solution in water? NH4Cl KNO3 NaF LiI

NH4Cl

Which one of the following salts, when 1 mole is dissolved in water, produces the solution with a pH closest to 7.00? KOH NH4Br RbF Na2O Na Cl

Na Cl

What is the conjugate base of HPO42- ?

PO43-

A _____ acid contains more than one ionizable proton.

Polyprotic

Qualitative analysis is a method that uses _________ in a systematic way to determine which metal ions are present in an unknown solution.

Selective precipitation

A solution containing AgNO3 is mixed with a solution of NaCl to form a solution that is 0.10 M in AgNO3 and 0.075 M in NaCl. What will happen once these solutions are mixed? Ksp (AgCl) = 1.77 × 10-10.

Silver chloride will precipitate out of solution, leaving a saturated AgCl solution.

Explain the common-ion effect with respect to molar solubility.

The common-ion effect occurs when a solubility equilibrium is shifted upon adding a second compound that contains an ion shared with the first.

A ligand is a molecule or ion that acts as __________.

a Lewis base

A complex ion contains

a central metal ion bound to one or more ligands.

What is the autoionization of water?

a process where water acts as an acid and a base when it reacts with itself.

A buffer is __________.

an aqueous solution that contains significant amounts of either a weak acid and its conjugate base or a weak base and its conjugate acid, enabling the buffer to resist pH changes by neutralizing the added acid or added base. Submit

A solution is prepared by dissolving 0.25 mol of hydrazoic acid and 0.26 mol of sodium azide in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the ________ present in the buffer solution. The Ka of hydrazoic acid is 2.5 × 10-5.

azide ion

If an equal number of moles of the weak acid HCN and the strong base LiOH are added to water, is the resulting solution acidic, basic, or neutral?

basic

A strong electrolyte ______ in solution.

completely ionizes

An assembly of a metal ion and the Lewis bases bonded to it is called a __________.

complex ion

A Lewis base

electron pair donor

The Lewis model describes the transfer of

electron pairs

A solution is prepared by dissolving 0.23 mol of hydrocyanic acid and 0.24 mol of sodium cyanide in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of NaOH to this buffer solution causes the pH to increase slightly. The pH does not increase drastically because the NaOH reacts with the ________ present in the buffer solution. The Ka of hydrocyanic acid is 4.9 × 10-10

hydrocyanic acid

When titrating a hydrochloric acid solution with a potassium hydroxide at 25°C, the

pH will be equal to 7 at the equivalence point.

When titrating acetic acid with sodium hydroxide at 25°C, the

pH will be greater than 7 at the equivalence point.

When titrating a weak base with HClHCl at 25 ∘C∘C, the

pH will be less than 7 at the equivalence point.

When titrating ammonia with a hydrochloric acid at 25°C, the

pH will be less than 7 at the equivalence point.

An Arrhenius acid

produces H+H+ in aqueous solutions.

The common-ion effect refers to the observation_________.

that the addition of a second solute that furnishes a common ion tends to decrease the solubility of a slightly soluble salt.

The stronger the acid, then which of the following is TRUE?

the weaker the conjugate base

When a diprotic acid is titrated with a strong base, and the Ka1 and Ka2 are significantly different, then the pHvs. volume plot of the titration will have

two distinct equivalence points.