Ch 19
Which of the following hydroxides will dissolve in basic solution? Select all that apply.
Al(OH)3 (s) Zn(OH)2 (s)
In the titration of a strong acid with a strong base, the equivalence point occurs when ______.
the number of moles of added OH- ions equals the number of moles of H3O+ initially present
Which of the following can NOT be used as an acid-base buffer solution? Select all that apply. Multiple select question.
0.5 M HNO3 and 0.5 M NaNO3 0.3 M HCl and 0.3 M NaOH
Which of the following options correctly describes the function of an acid-base buffer?
A buffer minimizes changes in pH when acid or base is added to the solution.
Which of the following descriptions are correct for an acid-base indicator? Choose all that apply.
A typical indicator changes color over a range of about 2 pH units. The color of the indicator changes over a specific pH range. Only a small amount of indicator is needed during a titration.
The Ksp for Fe(OH)2 is 4.1 x 10-15. Which of the following procedures would increase the solubility of Fe(OH)2? Select all that apply. Multiple select question.
Addition of 1.0 M HCl (aq) Addition of 1.0 M NaCN (aq)
Which of the following statements correctly describe a saturated solution of a slightly soluble ionic compound in H2O? Select all that apply.
An equilibrium exists between the undissolved and dissolved solute. The dissolved solute is assumed to be dissociated into ions.
Which of the following steps correctly show how to calculate the solubility for Pb(IO3)2 given that Ksp = 2.6 × 10-13? Select all that apply.
Assume that [Pb2+] = S, then [IO3-] = 2S. Ksp = 4S3
In what way is the titration curve for a weak base-strong acid titration similar to the titration curve for a weak acid-strong base titration? Multiple choice question.
Both have a buffer region before the equivalence point is reached.
The solubility of MgCO3 in water at 25°C is equal to 1.6 × 10-3 g per 100 mL. Which of the following options correctly reflect the steps required to calculate Ksp for this compound? Select all that apply. Multiple select question.
Calculate molar solubility by converting g/100 mL to mol/L. The molar solubility will give both [Mg2+] and [CO32-]. Calculate the molar mass for MgCO3.
When Na2CO3 is added to a saturated solution of BaCO3, the equilibrium will shift by _____ the amount of barium ions in solution, thus _____ the solubility of BaCO3.
Decrease, decrease
Under what conditions will a precipitate definitely not form when an aqueous solution of AgNO3 is added to an aqueous solution of NaCl?
If Qsp < Ksp
When can Ksp values be used to compare the relative solubilities of two ionic compounds?
If the formulas of the compounds contain the same total number of ions
For a slightly soluble ionic compound such as Ag2SO4, Qsp = [Ag+]2[SO42-] is called the ionBlank 1Blank 1 ion , Correct Unavailable -product expression. The value of Qsp for a saturated solution is the solubilityBlank 2Blank 2 solubility , Correct Unavailable -product constant Ksp, which represents the equilibrium constant for the dissolution process at a given temperature.
Ion, solubility
Calculate the Ksp of Fe(OH)3 given the equilibrium concentrations [Fe3+] = 9.3 × 10-11 M and [OH-] = 2.8 × 10-10 M.
Ksp = 2.0 × 10-39
Which of the following steps correctly show how to calculate the solubility for Pb(IO3)2 given that Ksp = 2.6 × 10-13? Select all that apply.
Ksp = 4S3 Assume that [Pb2+] = S, then [IO3-] = 2S.
Which of the following is the correct Ksp expression for the reaction Al(OH)3 (s) ⇌ Al3+ (aq) + 3OH- (aq)?
Ksp = [Al3+][OH-]3
Question Mode Multiple Select Question Select all that apply Which of the following statements correctly describe the solubility product constant Ksp for a slightly soluble substance? Select all that apply
Ksp is independent of the concentrations of the ions in solution. The value of Ksp indicates how far a dissolution equilibrium proceeds in favor of dissolved solute. Ksp depends on the temperature of the solution.
Consider the equilibrium system NH3 (aq) + H2O (l) ⇌ NH4+ (aq) + OH- (aq). If some solid NH4Cl were added to the system, the equilibrium would shift to the _____ and the [OH-] would _____.
Left; Decrease
A slightly soluble ionic compound will dissolve to a small extent in H2O, and a saturated solution is formed at a fairly dBlank 1Blank 1 d , Incorrect Unavailable solute concentration. At this point there is a(n) fBlank 2Blank 2 f , Incorrect Unavailable between undissolved solid and the dissociated ions in solution.
Low, equilbirum
In order to separate two ionic compounds by selective precipitation, a solution of a precipitating ion is added to the mixture until the Qsp of the ____ soluble compound is almost equal to its Ksp. This ensures that the Ksp of the ____ soluble compound is exceeded as much as possible and a maximum amount of it will precipitate.
More;less
Which of the following combinations could be used in an acid-base buffer system? Select all that apply.
NH3 /NH4Cl CH3COOH/NaCH3COO HNO2 /KNO2
Consider the reaction PbSO4 (s) ⇌ Pb2+ (aq) + SO42- (aq). When Na2SO4 is added to the system, the presence of the common ion _____ causes the equilibrium to shift toward the _____ and the solubility of PbSO4 will _____, in accordance with Le Chatelier's principle. Multiple choice question.
SO42-; reactants; decrease
Which slightly soluble ionic salts will become more soluble at lower pH?
Salts that contain the anion of a weak acid
Which of the following options correctly describe the differences between the titration curve for a weak acid-strong base titration and a strong acid-strong base titration? Select all that apply.
The pH at the equivalence point is above 7.00 for the weak acid-strong base titration. The curve for the weak acid-strong base titration rises gradually through a buffer region before the steep rise to the equivalence point.
Which of the following statements correctly describe the titration curve for the titration of a strong acid with a strong base? Select all that apply. Multiple select question.
The pH rise is very steep close to the equivalence point of the titration. The equivalence point is at a pH of 7.00.
Consider the dissociation of the weak acid HClO2, which can be represented by the balanced equation HClO2 (aq) + H2O (l) ⇌ ClO2- (aq) + H3O+ (aq). Which of the following options correctly describe the effect of adding solid KClO2 to this system? Select all that apply. Multiple select question.
The solution pH will increase. The % dissociation of HClO2 will decrease.
In what way is the titration curve for a weak base-strong acid titration different to the titration curve for a weak acid-strong base titration?
The weak base-strong acid titration curve will have an equivalence point at pH < 7.00.
An indicator is a(n) strongBlank 1Blank 1 strong , Incorrect Unavailable organic acid that has a different color than its weakBlank 2Blank 2 weak , Incorrect Unavailable base. Each indicator changes color over a specific, narrow curveBlank 3Blank 3 curve , Incorrect Unavailable range.
Weak, conjugate, pH
The pH of the solution depends on the ratio [HA][A−][HA][A-]. If the relative amount of HA is increased, the solution pH will decrease.
Which of the following statements correctly reflect the relationship between buffer composition and solution pH given that Ka = [H3O+][A−][HA][H3O+][A-][HA]? Select all that apply. Multiple select question.
The solubility of Ag2CrO4 in water is equal to 0.029 g per 1 L of solution at 25oC. Which of the following options correctly reflect the steps required to calculate Ksp for this compound from the given information? Select all that apply.
[CrO42-] = 8.7 x 10-5 M Molar solubility = 0.029g1L0.029g1L x 1mol331.8g1mol331.8g = 8.7 x 10-5 M Ag2CrO4 Ksp = 2.5 x 10-12
A complex ion is formed between a metal ion, acting as a Lewis mBlank 1Blank 1 m , Incorrect Unavailable, and a ligand acting as a Lewis mBlank 2Blank 2 m , Incorrect Unavailable. When the ligand is a lBlank 3Blank 3 l , Incorrect Unavailable Lewis base than H2O, the metal ion will form a complex ion with the ligand rather than with water.
acid, base, stronger
An amino acid has a COOH group, which is a weak _____, and an NH2 group, which is a weak ____. At _____ pH both groups are protonated, but at physiological pH (around 7.00) the compound exists as a zwitterion, a species with opposite charges on the same molecule. Multiple choice question.
acid; base; low
In a 0.75 M HF solution, the HF is 2.2% dissociated. When NaF (s) is added to this solution the percent dissociation of HF _____ and the pH of the resulting solution will be _____ than its original value. This effect is due to the addition of the common ion _____.
decreases; higher; F-
A complex ion consists of a central kBlank 1Blank 1 k , Incorrect Unavailable ion covalently bonded to two or more anions or molecules, which are called mBlank 2Blank 2 m , Incorrect Unavailable.
metal; ligands
An amino acid contains a weakly aBlank 1Blank 1 a , Incorrect Unavailable amino group (NH2) and a weakly fBlank 2Blank 2 f , Incorrect Unavailable carboxyl group (COOH). At low pH both groups are protonated, but at physiological pH (pH = 7.2) the compound exists as a fBlank 3Blank 3 f , Incorrect Unavailable, a species with opposite charges on the same molecule.
Basic, acidic, zwitteron
Which of the statements correctly describe selective precipitation? Select all that apply.
Selective precipitation is the separation of a mixture based upon the components' solubilities. Selective precipitation involves forming precipitates with specific classes of ions as a means for separation.
Which of the following should be considered when selecting/preparing a buffer solution? Select all that apply.
The buffer capacity will be higher if more concentrated solutions are used. The pKa of the acid component of the buffer should be close to the desired pH.
Which of the following options correctly describe the factors affecting buffer capacity? Select all that apply.
The closer the ratio [HA][A−][HA][A-] is to 1, the higher the buffer capacity. The more concentrated the buffer components, the greater the buffer capacity.
If NaClO (aq) is added to the reaction shown below, which of the following statements would be true? Select all that apply. HClO (aq) + H2O (l) ⇌ ClO- (aq) + H3O+ (aq)
The concentration of HClO (aq) would increase. The pH of the solution would increase.
Which of the following statements correctly describe the titration curve for the titration of a strong acid with a strong base? Select all that apply.
The equivalence point is at a pH of 7.00. The pH rise is very steep close to the equivalence point of the titration.
