CHM2046 STUDYING: ONLINE QUIZ QUESTIONS
Which metal below would make an appropriate metallic container in which to store an aqueous cobalt(II) chloride solution? (1) aluminum (2) iron (3) zinc (4) tin (5) none of these metals
(4) tin
Which of the following metals does not react with cold water to form H2 gas? (1) Ba (2) Fe (3) K (4) Sr (5) Ca
(2) Fe
Which of the following metals does not react with cold water to form H2 gas? (1) Ca (2) Fe (3) K (4) Ba (5) Sr
(2) Fe
Which of the following is the oxidation half-reaction of this oxidation-reduction reaction? Mg(s) + 2Ag+(aq) → Mg2+(aq) + 2Ag(s) (1) 2Ag+(aq) + 2e− → 2Ag(s) (2) Mg(s) → Mg2+(aq) + 2e− (3) 2Ag(s) → 2Ag+(aq) + 2e− (4) Mg2+(aq) + 2e− → Mg(s)
(2) Mg(s) → Mg2+(aq) + 2e−
Select the true statement below. (1) 0.10 M formic acid exhibits a higher pH than does 0.20 M formic acid (2) 0.10 M formic acid exhibits a lower %-ionization than does 0.20 M formic acid (3) none of these statements are true (4) 0.10 M formic acid exhibits a lower Ka than does 0.20 M formic acid (5) 0.10 M formic acid is more acidic than 0.20 M formic acid
(1) 0.10 M formic acid exhibits a higher pH than does 0.20 M formic acid
In which of the following reactions do you predict an increase in entropy (a positive ΔS)? (1) 2ClF3(l) + 2 O2(g) → Cl2O(g) + 3OF2(g) (2) 2ClF(g) + O2(g) → Cl2O(g) + OF2(g) (3) PCl3(g) + Cl2(g) → PCl5(g) (4) Si(s) + 2Cl2(g) → SiCl4(g)
(1) 2ClF3(l) + 2 O2(g) → Cl2O(g) + 3OF2(g)
Identify the Lewis acids in the following two equilbrium systems: System A: CO2 + H2O ↔ H2CO3 System B: Zn2+ + 6H2O ↔ Zn(H2O)62+ (1) A: CO2; B: Zn2+ (2) A: H2O; B: H2O (3) A: H2O; B: Zn2+ (4) A: CO2; B: system B is not a Lewis acid-base system (5) A: CO2; B: H2O
(1) A: CO2; B: Zn2+
It would not be wise to store a chromium(III) nitrate solution in an aluminum container. Why? (1) Al is a stronger reducing agent than Cr (2) Cr3+ is a stronger reducing agent than Al3+ (3) Al3+ is a stronger oxidizing agent than Cr3+ (4) Cr is a stronger oxidizing agent than Al
(1) Al is a stronger reducing agent than Cr
Consider the following equilibrium at 25°C and select the false statement below. N2H4(g) ↔ N2(g) + 2H2(g) ΔH°rxn = ‒95 kJ (1) Keq < 1 (2) ΔG = 0 (3) ΔS° is positive (4) ΔG° is negative (5) Qeq = Keq
(1) Keq < 1
If you slowly add NaOH(aq) to an aqueous solution containing the same concentration of Mg2+ and Ca2+ ions, which solid will precipitate out first? Ksp of Mg(OH)2 = 1.2 x 10−11 and Ksp of Ca(OH)2 = 8.0 x 10−6 (1) Mg(OH)2 (2) Ca(OH)2
(1) Mg(OH)2
Predict what reaction, if any, occurs (at 25°C) when manganese metal is added to a 1.0 M solution of HCl. (1) Mn(s) + 2H+(aq) → Mn2+(aq) + H2(g) (2) Mn(s) + 2HCl(aq) → Mn2+(aq) + Cl2(g) + H2(g) (3) 2Mn(s) + O2(g) + 4H+(aq) → 2Mn2+(aq) + 2H2O(aq) (4) no reaction (5) Mn2+(aq) + H2(g) → Mn(s) + 2H+(aq)
(1) Mn(s) + 2H+(aq) → Mn2+(aq) + H2(g)
Which statement is false? (1) Ni2+(aq) + CO32-(aq) → NiCO3(s) is a Lewis acid-base reaction (2) all Brønsted-Lowry bases are also potential Lewis bases (3) H+(aq) + H2O(l) → H3O+(aq) is a Lewis acid-base reaction (4) BF3 + F- → BF4- is a Lewis acid-base reaction (5) Ni2+(aq) + 6H2O(l) → [Ni(H2O)6]2+(aq) is a Lewis acid-base reaction (6) HNO2 is a Brønsted-Lowry acid but is not a Lewis acid
(1) Ni2+(aq) + CO32-(aq) → NiCO3(s) is a Lewis acid-base reaction
A 1M aqueous solution of copper(II) nitrate is electrolyzed. What are the predicted products at the anode and cathode? Correct! (1) O2 gas at the anode; copper metal at the cathode (2) N2 gas at the anode; copper metal at the cathode (3) NO2 gas at the anode; copper metal at the cathode (4) NO2 gas at the anode; H2 gas at the cathode (5) O2 gas at the anode; H2 gas at the cathode
(1) O2 gas at the anode; copper metal at the cathode
Which of the following is a proper notation for the voltaic cell consisting of of one half-cell with a zinc electrode in 1 M Zn(NO3)2 solution and the other half-cell with a lead electrode in 1 M Pb(NO3)2 solution and a KNO3 salt bridge. (1) Zn(s) | Zn2+(1 M) || Pb2+(1 M) | Pb(s) (2) Pb2+(1 M) | Pb(s) || Zn(s) | Zn2+(1 M) (3) Pb(s) | Pb2+(1 M) || Zn2+(1 M) | Zn(s) (4) Zn2+(1 M) | Zn(s) || Pb(s) | Pb2+(1 M)
(1) Zn(s) | Zn2+(1 M) || Pb2+(1 M) | Pb(s)
Which of the following statements is true? (1) during our study of solubility equilibria, we've been making the assumption that the solutions follow Raoult's Law (2) fractional precipitation is a method of selectively removing ions from an aqueous solution based on different colligative properties (boiling point, vapor pressure, etc.) (3) the molar solubility s of a semisoluble salt MX2 (where M is the metal cation and X is the nonmetallic anion) is calculated by taking the square root of Ksp (4) precipitation occurs when, in an aqueous system at a certain temperature, the ion product Q is less than the solubility product constant Ksp at that temperature
(1) during our study of solubility equilibria, we've been making the assumption that the solutions follow Raoult's Law
Select the true statement below. Correct! (1) in a voltaic cell, the difference in chemical potential energy between higher energy reactants and lower energy products is converted into electrical energy (2) in an electrolytic cell, the difference in chemical potential energy between lower energy reactants and higher energy products is converted into electrical energy (3) a spontaneous redox reaction equation will have the stronger oxidizer and stronger reducer as products (4) in a voltaic cell, electrons flow from the cathode to the anode, giving the anode a negative charge (5) a salt bridge should contain ions that will participate in the redox reaction
(1) in a voltaic cell, the difference in chemical potential energy between higher energy reactants and lower energy products is converted into electrical energy
Consider the pH range for the following indicators and select the most appropriate indicator for the titration of an HCN solution with a NaOH titrant. (1) phenolphthalein, pH range 8.3-10.0 (2) thymol blue, pH range 1.2-2.8 (3) methyl red, pH range 4.2-6.3 (4) bromophenol blue, pH range 3.0-4.6 (5) bromothymol blue, pH range 6.0-7.6
(1) phenolphthalein, pH range 8.3-10.0
A sample of solid AlBr3 contaminated with solid KF is melted and electrolyzed. What is the resulting overall reaction? (1) 2K+(l) + 2F-(l) → 2K(s) + F2(g) (2) 2Al3+(l) + 6Br-(l) → 2Al(s) + 3Br2(l) (3) 2Al3+(l) + 2F-(l) → 2Al(s) + F2(g) (4) no reaction will occur (5) 2K+(l) + 2Br-(l) → 2K(s) + Br2(l)
(2) 2Al3+(l) + 6Br-(l) → 2Al(s) + 3Br2(l)
Determine which of the following three sulfate salts would be more soluble in pure water at 25°C. (There are only three answer options for this question) (1) CaSO4 (Ksp = 2.4 x 10−5) (2) Ag2SO4 (Ksp = 1.5 x 10−5) (3) SrSO4 (Ksp = 3.2 x 10−7)
(2) Ag2SO4 (Ksp = 1.5 x 10−5)
Which of the following can act as a Lewis base? Cr3+, SO3, CH3NH2, BeCl2 (1) SO3 only (2) CH3NH2 only (3) CH3NH2, BeCl2 (4) SO3, CH3NH2 (5) Cr3+, BeCl2
(2) CH3NH2 only
Which of the following oxides of chlorine would you predict to be the strongest oxidizing agent? (hint: which can be reduced the most?) (1) ClO2 (2) Cl2O7 (3) Cl2O3 (4) Cl2O6 (5) Cl2O
(2) Cl2O7
Consider the following reaction and select the false statement below. NaI + 3HOCl → NaIO3 + 3HCl (1) If ΔG° for the reaction is < 0, then NaI is a stronger reducing agent than HCl (2) If ΔG° for the reaction is < 0, then NaIO3 is a stronger oxidizing agent than HOCl (3) Cl is reduced (4) HOCl is the oxidizing agent (5) NaI is the reducing agent
(2) If ΔG° for the reaction is < 0, then NaIO3 is a stronger oxidizing agent than HOCl
Consider the following system: Si(s) + 2Cl2(g) ↔ SiCl4(g) ΔHrxn = - 657.0 kJ Which of the following statements is false? (1) Increasing the external pressure on the system at constant temperature will shift the equilibrium to the right to increase the production of SiCl4 (2) Increasing the temperature of the system at constant pressure will shift the equilibrium to the right to increase the production of SiCl4 (3) Increasing the amount of Si(s) will have no effect on the equilibrium dynamics of the system. (4) Adding an appropriate catalyst to the system may increase the rate of production of SiCl4 (5) Removing SiCl4 from the reaction vessel as it is produced will shift the equilibrium to the right to produce more SiCl4
(2) Increasing the temperature of the system at constant pressure will shift the equilibrium to the right to increase the production of SiCl4
Which of the following solutions can not act as a buffer? (1) NH3/NH4NO3 (2) NaI/HI (3) Na2SO4/NaHSO4 (4) KCN/HCN (5) Na3PO4/Na2HPO4
(2) NaI/HI
Is it safe to go swimming in the ocean while wearing silver jewelry? Why? (1) No it is not safe because Na+ is a strong oxidizing agent and will oxidize the Ag. (2) Yes it is safe because Na+ is not strong enough of an oxidizing agent to oxidize Ag. (3) No it is not safe because Na is a strong reducing agent and will reduce the Ag. (4) Yes it is safe because Na+ is not strong enough of a reducing agent to reduce Ag.
(2) Yes it is safe because Na+ is not strong enough of an oxidizing agent to oxidize Ag.
If Ka of HXO3 is > than Ka of HZO3 at 25°C, then it is most likely that..... (1) X exhibits a higher oxidation state than Z (2) HXO3(aq) + ZO3−(aq) ↔ XO3−(aq) + HZO3(aq) is reactant-favored at 25°C (3) X is more electronegative than Z (4) the H―X bond is weaker than the H―Z bond (5) Z is larger than X
(3) X is more electronegative than Z
Select the false statement below. (1) a 0.10 M NH4Cl solution is predicted to have a lower pH than a 0.10 M KCl solution (2) a 0.10 M NaHSO4 solution is predicted to have a pH > 7 (3) a 0.10 M Na2SO3 solution is predicted to have a higher pH than a 0.10 M NaHSO3 solution (4) a 0.10 M KNO3 solution is predicted to have a higher pH than a 0.10 M Pb(NO3)2 solution (5) a 0.10 M Na2HPO4 solution is predicted to have a lower pH than a 0.10 M Na3PO4 solution
(2) a 0.10 M NaHSO4 solution is predicted to have a pH > 7
Select the false statement below: (1) a 0.10 M Na2HPO4 solution is predicted to have a lower pH than a 0.10 M Na3PO4 solution (2) a 0.10 M NaHSO4 solution is predicted to have a pH > 7 (3) a 0.10 M KNO3 solution is predicted to have a higher pH than a 0.10 M Pb(NO3)2 solution (4) a 0.10 M NH4Cl solution is predicted to have a lower pH than a 0.10 M KCl solution (5) a 0.10 M Na2SO3 solution is predicted to have a higher pH than a 0.10 M NaHSO3 solution
(2) a 0.10 M NaHSO4 solution is predicted to have a pH > 7
A spontaneous process must lead to: (1) a net decrease in the entropy of the universe (2) a net increase in the entropy of the universe (3) an increase in the entropy of the system (4) a decrease in the entropy of the surroundings (5) an increase in the entropy of the surroundings
(2) a net increase in the entropy of the universe
Elements such as Mn and Cr and Cl and N and Br, etc., exhibit their highest oxidation states when combined with what kind of elements in compounds? (1) relatively electopositive elements such as carbon or hydrogen (2) relatively electronegative elements such as oxygen or fluorine
(2) relatively electronegative elements such as oxygen or fluorine
Which of the following statements about the electrochemical process involved in rust formation on iron objects is false? (1) the loss of iron and the depositing of rust typically occur at different places on the same object (2) rusting can be inhibited by alloying the iron with tin (3) iron rusts more quickly in contact with acidic solutions (4) the iron object acts as both the anode and the cathode when iron is lost (5) iron rusts more quickly in contact with ionic solutions
(2) rusting can be inhibited by alloying the iron with tin
The equilibrium reaction CaCO3(s) ↔ CaO(s) + CO2(g) reaches ΔG° = 0 at 835°C. At this temperature: (1) the reaction becomes exothermic (2) the pressure of CO2 is 1 atm (3) the decomposition of CaCO3 begins (4) ΔH° = ΔS° (5) the percent yield of CaO reaches 100%
(2) the pressure of CO2 is 1 atm
Which of the following would not be a redox reaction? (1) the reaction between iron metal and sulfur to form iron(II) sulfide (2) the reaction that occurs when aqueous calcium chloride is mixed with aqueous sodium carbonate (3) the reaction between zinc metal and aqueous hydrochloric acid (4) the reaction that occurs when gaseous chlorine is bubbled through an aqueous potassium iodide solution (5) the combustion of a hydrocarbon in oxygen gas
(2) the reaction that occurs when aqueous calcium chloride is mixed with aqueous sodium carbonate
Consider the following system which has been shown to be spontaneous at 298K and select the true statement below. N2(g) + 3H2(g) → 2NH3(g) (1) the ΔS for the system is predicted to be negative, so therefore the ΔS for the surroundings must be positive to a lesser extent so that the the net ΔS for the universe is negative (2) the ΔS for the system is predicted to be negative, so therefore the ΔS for the surroundings must be positive to a greater extent so that the the net ΔS for the universe is positive (3) the ΔS for the system is predicted to be positive, so therefore the ΔS for the surroundings must be positive also so that the the net ΔS for the universe is positive (4) the ΔS for the system is predicted to be positive, so therefore the ΔS for the surroundings must be negative to a lesser extent so that the the net ΔS for the universe is positive
(2) the ΔS for the system is predicted to be negative, so therefore the ΔS for the surroundings must be positive to a greater extent so that the the net ΔS for the universe is positive
Select the true statement below. (1) when Q < K, the system can release no more free energy (2) when ΔG < 0, the system can release free energy until Q = K (3) when ΔG > 0, ΔG is the maximum useful work obtainable from the system (4) when ΔG > 0, the system can release free energy (5) when ΔG = 0, ΔG° must also = 0
(2) when ΔG < 0, the system can release free energy until Q = K
Balance this equation for the reaction of Zn(s) with Cr2O72-(aq) in acidic aqueous solution: Zn(s) + Cr2O7 2-(aq) → Cr 3+(aq) + Zn 2+(aq) (1) 3Zn(s) + Cr2O72-(aq) → 2Cr3+(aq) + 3Zn2+(aq) (2) 3Zn(s) + Cr2O72-(aq) + 7H2O(l) → 2Cr3+(aq) + 3Zn2+(aq) + 14OH-(aq) (3) 3Zn(s) + Cr2O72-(aq) + 14H+ → 2Cr3+(aq) + 3Zn2+(aq) + 7H2O(l) (4) 2Zn(s) + Cr2O72-(aq) + 2H+(aq) → 2Cr3+(aq) + 2Zn2+(aq) + 6O2-(g) + H2O
(3) 3Zn(s) + Cr2O72-(aq) + 14H+ → 2Cr3+(aq) + 3Zn2+(aq) + 7H2O(l)
Consider the following equilibrium system at 25°C and select the true statement below: HA(aq) + H2O(l) ↔ H3O+(aq) + A−(aq) Ka = 1.0 x 10−4 at 25°C (1) a solution of NaA(s) dissolved in pure water is predicted to have a pH < 7.00 at 25°C (2) this is a product-favored system at 25°C (3) A− is a stronger base than H2O (4) HA is a stronger acid than H3O+ (5) (Kb of A−) = 1 / (Ka of HA)
(3) A− is a stronger base than H2O
Chlorine gas (at 1 atm pressure) is added to an aqueous solution containing 1.0 M NaBr and 1.0 M NaF at 25°C. What is the predicted product, if any? (1) F2(g) (2) no reaction (3) Br2(l) (4) K(s) (5) Na(s)
(3) Br2(l)
An aqueous solution containing 1M of each of following dissolved salts is electrolyzed. What products are produced at the anode (an) and cathode (cat)? (dissolved salts: NaBr, Al(NO3)3, NiSO4) (1) Br2(l) an, H2(g) cat (2) O2(g) an, Ni(s) cat (3) Br2(l) an, Ni(s) cat (4) SO2(g) an, Ni(s) cat (5) O2(g) an, H2(g) cat
(3) Br2(l) an, Ni(s) cat
Which one of the following metals would serve as a sacrificial anode for the cathodic protection of a tin (Sn) object? (1) v (2) Ag (3) Fe (4) Cu (5) Au
(3) Fe
Predict what reaction, if any, occurs (at 25°C) when manganese metal is added to a 1.0 M solution of HCl. (1) 2Mn(s) + O2(g) + 4H+(aq) → 2Mn2+(aq) + 2H2O(aq) (2) no reaction (3) Mn(s) + 2H+(aq) → Mn2+(aq) + H2(g) (4) Mn(s) + 2HCl(aq) → Mn2+(aq) + Cl2(g) + H2(g) (5) Mn2+(aq) + H2(g) → Mn(s) + 2H+(aq)
(3) Mn(s) + 2H+(aq) → Mn2+(aq) + H2(g)
Which of the following statements is true? (1) if Qeq > Keq, equilibrium is re-established by shifting to the right at constant temperature (2) a good "nitrate buffer" system might be NO3−/HNO3 (3) a buffer system is at its optimum capacity when the ratio [A−]/[HA] = 1 (4) for the system HA(aq) + B−(aq) ↔ A−(aq) + HB(aq), Keq = (Ka of HA)(Kb of B−) (5) the %-dissociation of a weak acid increases with increasing initial acid concentration
(3) a buffer system is at its optimum capacity when the ratio [A−]/[HA] = 1
In thermochemistry, a "coupled reaction" is based on the concept that: (1) "like dissolves like" and "opposites attract" (2) a nonstandard-state reaction can be "coupled" with a standard-state reaction to result in a spontaneous process (negative ΔG) (3) a thermodynamically favorable reaction can be used to drive a thermodynamically unfavorable reaction by "coupling" the two reactions together simultaneously (4) all reactions reach a thermodynamic equilibrium ("coupling") at a specific set of conditions (5) the enthalpy and entropy of a reaction are interdependent ("coupled") on each other
(3) a thermodynamically favorable reaction can be used to drive a thermodynamically unfavorable reaction by "coupling" the two reactions together simultaneously
Answer the following questions: a) can Al3+(aq) oxidize tin (Sn) under standard-state conditions?; b) would it be OK to store an aqueous AlCl3 solution in a tin container?; c) can Sn2+(aq) oxidize aluminum (Al) under standard state conditions?; d) would it be OK to store an aquous SnCl2 solution in an aluminum container? (1) a) yes; b) no; c) no; d) yes (2) a) yes; b) yes; c) no; d) no (3) a) no; b) yes; c) yes; d) no (4) a) no; b) no; c) yes; d) yes
(3) a) no; b) yes; c) yes; d) no
Select the false statement below. (1) all Arrhenius acids are Brønsted-Lowry acids (2) H2O is a potential Brønsted-Lowry acid and also a potential Brønsted-Lowry base (3) all Brønsted-Lowry bases are Arrhenius bases (4) H2PO4- is a potential Brønsted-Lowry acid and also a potential Brønsted-Lowry base (5) Arrhenius bases contain the Brønsted-Lowry base OH-
(3) all Brønsted-Lowry bases are Arrhenius bases
Which of the following statements involving ammonia is false ? (1) ammonia is a stronger base than H2O, but ammonia is a weaker base than OH− (2) ammonia can act as a Brønsted-Lowry base or a Lewis base (3) at the equivalence point of a titration of aqueous NH3 with aqueous HCl, the pH should be > 7 (4) store-bought aqueous NH3 has a pungent smell because NH3 does not completely hydrolyze water (5) the following reaction is a Lewis acid-base reaction : Ag+(aq) + 2NH3(aq) ↔ Ag(NH3)2+(aq)
(3) at the equivalence point of a titration of aqueous NH3 with aqueous HCl, the pH should be > 7
Select the true statement below. (1) a hydrogen fuel cell is an electrolytic cell which produces H2 fuel for combustion (2) the presence of aqueous H3O+ ions inhibits rust formation (3) batteries act as galvanic/voltaic cells during discharge, and as electrolytic cells during recharge (4) the relatively high potential of the lithium-ion battery is due to lithium being a strong oxidizer (5) rusting of metal A may be inhibited by alloying or coating metal A with a less reactive metal B
(3) batteries act as galvanic/voltaic cells during discharge, and as electrolytic cells during recharge
Consider the following equations and select the false statement below: FeCl3(s) + 6H2O(l) → Fe(H2O)63+(aq) + 3Cl−(aq) Fe(H2O)63+(aq) + H2O(l) ↔ Fe(H2O)5(OH)2+(aq) + H3O+(aq) (1) the iron(III) ion has a relatively high positive charge density (2) the iron(III) ion acts as a Lewis acid in the 1st equation (3) if Fe(NO3)3(s) were used instead of FeCl3(s), different results would have been obtained (4) the hydrated iron(III) ion acts as an acid in the 2nd equation (5) the iron(III) ion withdraws electron density from the O―H bonds in the bonded water molecules, resulting in more polar O―H bonds
(3) if Fe(NO3)3(s) were used instead of FeCl3(s), different results would have been obtained
Consider the following reactions and select the false statement below. CO2(g) + OH−(aq) → HCO3−(aq) Cr3+(aq) + 6H2O(l) → Cr(H2O)63+(aq) (1) both HCO3- and Cr(H2O)63+ are Lewis acid-base adducts (2) a lone pair of electrons on the OH− forms a coordinate covalent bond with the C in CO2 (3) in Cr(H2O)63+ the Cr3+ is attracted to the H2O molecules via ion-dipole intermolecular forces (4) CO2 is a Lewis acid (5) Cr3+ is a Lewis acid
(3) in Cr(H2O)63+ the Cr3+ is attracted to the H2O molecules via ion-dipole intermolecular forces
Consider the following four aqueous solutions: NaBr(aq), K2SO3(aq), NH4Cl(aq), and Cr(NO3)3(aq). The solutions will be (respectively): (1) acidic, basic, acidic, and acidic (2) neutral, acidic, basic, and acidic (3) neutral, basic, acidic, and acidic (4) neutral, acidic, basic, and basic (5) basic, basic, acidic, and acidic
(3) neutral, basic, acidic, and acidic
Select the true statement from the following. (1) the percent ionization of a base increases with its concentration in solution (2) an aqueous solution of barium fluoride is acidic (3) none of these statements are true (other than this one, of course) (4) the conjugate base of an acid always carries a negative charge (5) all Brønsted-Lowry bases are also Arrhenius bases
(3) none of these statements are true (other than this one, of course)
Consider the following comparisons and select the answer that would most seem to account for the comparisons. HClO4 is a stronger acid than HClO3 HNO3 is a stronger acid than HNO2 H2SO4 is a stronger acid than H2SO3 (1) perhaps the electronegativity of the X (X being Cl, N, or S) is greater in the first acid of each pair (2) perhaps the molecular polarity of the first acid of each pair is greater (3) perhaps the molecules with the greatest acid potential in each pair contain more oxygen atoms (4) perhaps the H—X bond (X being either Cl, N, or S) is weaker in the first acid of each pair
(3) perhaps the molecules with the greatest acid potential in each pair contain more oxygen atoms
Nitric acid is a strong acid, but nitrous acid is a weak acid. Why? (1) the N atom in nitric acid is slightly larger than the N atom in nitrous acid (2) the higher oxidation state of the N atom results in a weaker N―H bond (3) the electronegativity of the N atom in greater in nitric acid than it is in nitrous acid (4) there are more electronegative oxygen atoms bonded to the N atom, resulting in a higher oxidation state of the N atom and resulting in a more polar O―H bond (5) the nitrate ion is a stronger base than the nitrite ion
(4) there are more electronegative oxygen atoms bonded to the N atom, resulting in a higher oxidation state of the N atom and resulting in a more polar O―H bond
The exothermic reaction NH3(g) + HCl(g) → NH4Cl(s) proceeds spontaneously at 25°C even though there is a decrease in disorder in the system (gases producing a solid). Why? (1) the decrease in entropy of the system is offset by an increase in the entropy of the surroundings caused by the absorption of heat by the system from the surroundings (2) there is a phase change from gases to solid which means ΔG is zero which, when combined with a negative ΔH, results in a spontaneous process (3) the decrease in entropy of the system is offset by an increase in the entropy of the surroundings caused by the release of heat from the system to the surroundings (4) the exothermic reaction increases the temperature from 25°C to a higher temperature which increases the TΔS component
(3) the decrease in entropy of the system is offset by an increase in the entropy of the surroundings caused by the release of heat from the system to the surroundings
Consider the following equilibrium at 25°C: MX(s) ↔ M+(aq) + X-(aq) ΔG° > 0 at 25°C Which of the following statements is true? (1) Ksp of MX(s) must be > 1 (2) precipitation begins when ΔG° = 0 (3) when ΔG° = 0, [M+] = [X-] = 1.0 M (4) no dissolution of MX(s) will occur until the system is heated to the point where ΔG° < 0 (5) if Qsp/Ksp = 1, then ΔG° must be = 0
(3) when ΔG° = 0, [M+] = [X-] = 1.0 M
In which of the following aqueous acid solutions would you expect the lowest %-dissociation of the acid? (1) 0.1 M H3PO4 (2) 0.001 M HClO4 (3) 0.01 M HClO4 (4) 1.0 M H3PO4 (5) 0.01 M H3PO4
(4) 1.0 M H3PO4
Which of the following reactions is spontaneous at low temperatures but nonspontaneous at high temperatures? (1) N2(g) + 3Cl2(g) → 2NCl3(l) ΔH° = +230 kJ (2) C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l) ΔH° = -2816 kJ (3) CaO(s) + 3C(s) → CaC2(s) + CO(g) ΔH° = +462 kJ (4) CS2(g) + 3Cl2(g) → CCl4(g) + S2Cl2(g) ΔH° = -238 kJ (5) C6H5OH(s) → C6H5OH(l) (ΔH° should be inferred by student)
(4) CS2(g) + 3Cl2(g) → CCl4(g) + S2Cl2(g) ΔH° = -238 kJ
Which of the following reactions would be predicted to be spontaneous at room temperature? (1) Br2(l) + 2Cl-(aq) → 2Br-(aq) + Cl2(g) (2) Cl2(g) + 2F-(aq) → 2Cl-(aq) + F2(g) (3) I2(s) + 2Br-(aq) → 2I-(aq) + Br2(l) (4) Cl2(g) + 2Br-(aq) → 2Cl-(aq) + Br2(l)
(4) Cl2(g) + 2Br-(aq) → 2Cl-(aq) + Br2(l)
Which of the following is the oxidation half-reaction of this oxidation-reduction reaction? Mg(s) + 2Ag+(aq) → Mg2+(aq) + 2Ag(s) (1) 2Ag+(aq) + 2e− → 2Ag(s) (2) Mg2+(aq) + 2e− → Mg(s) (3) 2Ag(s) → 2Ag+(aq) + 2e− (4) Mg(s) → Mg2+(aq) + 2e−
(4) Mg(s) → Mg2+(aq) + 2e−
In which pair of substances below does the substance with the greater entropy not follow the substance with the lesser entropy? (1) LiF(s), RbI(s) (2) KOH(s), KOH(aq) (3) C4H10, C6H14 (4) NO2(g), N2(g) (5) CO2(aq), CO2(g)
(4) NO2(g), N2(g)
Which statement is false? (1) HNO2 is a Brønsted-Lowry acid but is not a Lewis acid (2) all Brønsted-Lowry bases are also potential Lewis bases (3) H+(aq) + H2O(l) → H3O+(aq) is a Lewis acid-base reaction (4) Ni2+(aq) + CO32-(aq) → NiCO3(s) is a Lewis acid-base reaction (5) Ni2+(aq) + 6H2O(l) → [Ni(H2O)6]2+(aq) is a Lewis acid-base reaction (6) BF3 + F- → BF4- is a Lewis acid-base reaction
(4) Ni2+(aq) + CO32-(aq) → NiCO3(s) is a Lewis acid-base reaction
Sugar is produced by photosynthesis in the reaction below. Which of the following steps would not increase the yield of the sugar (C6H12O6)? 6CO2(g) + 6H2O(l) ↔ C6H12O6(s) + 6O2(g) ΔHreaction = (+) (a) increase the partial pressure of CO2 (b) increase the temperature (c) increase the partial pressure of O2 (d) remove all of the C6H12O6 as it is formed (e) increase the amount of water present (f) add an appropriate catalyst (g) increase in total pressure (h) decrease the temperature (1) a,b,d,f,h (2) c,e,f,h (3) d,e,f,h (4) c,e,f,g,h (5) b,c,e
(4) c,e,f,g,h
The theoretical solubility of calcium phosphate can be calculated from its Ksp value, but its actual observed solubility is greater than its calculated theoretical solubility. Why? (1) hydrolysis involving the calcium ion acts to shift the calcium phosphate solubility equilibrium to the right, increasing the solubility of the calcium phosphate (2) hydration of the calcium ion produces an acidic solution which results in a greater solubility of calcium phosphate (3) hydrolysis involving the phosphate ion acts to shift the calcium phosphate solubility equilibrium to the left, increasing the solubility of the calcium phosphate (4) hydrolysis involving the phosphate ion acts to shift the calcium phosphate solubility equilibrium to the right, increasing the solubility of the calcium phosphate (5) hydrolysis involving the calcium ion acts to shift the calcium phosphate solubility equilibrium to the left, increasing the solubility of the calcium phosphate
(4) hydrolysis involving the phosphate ion acts to shift the calcium phosphate solubility equilibrium to the right, increasing the solubility of the calcium phosphate
A lab student was preparing to electrolyze a 1M aqueous solution of sodium iodide to obtain the predicted products thereof, when he discovered that the solution had been accidentally contaminated with potassium bromide by another lab student. Should he be concerned? (1) yes, because instead of the predicted H2 and OH− produced at the cathode, K will be produced (2) no, because the predicted Na will be produced at the cathode, even in the presence of K+ ions (3) yes, because instead of the predicted I2 produced at the anode, O2 and H+ will be produced (4) no, because the predicted I2 will still be produced at the anode, even in the presence of Br− ions (5) yes, because instead of the predicted I2 produced at the anode, Br2 will be produced at the anode
(4) no, because the predicted I2 will still be produced at the anode, even in the presence of Br− ions
Which of the following most consistently defines the potential of an acid under a given set of conditions? (1) all of these values consistently define the potential of an acid under a given set of conditions (2) the %-ionization (or %-dissociation) of the acid (3) the pH of the acid (4) the Ka of the acid (5) the concentration of the acid, [HA]
(4) the Ka of the acid
It is determined that aqueous solutions of the sodium salts NaX, NaY, and NaZ have pH values of 7.0, 8.0, and 9.0, respectively. Which one of the following statements is false? (1) the Na+ cation does not hydrolyze H2O (2) the Kb for Y- is greater than the Kb for X- (3) the following acids are ordered in order of decreasing acid strength: HX > HY > HZ (4) the X- anion is the conjugate base of a weak acid HX (5) the Z- anion is a stronger base than the Y- anion
(4) the X- anion is the conjugate base of a weak acid HX
Which of the following reactions is likely to take place spontaneously? (1) Pb(s) + 2H2O(l) → H2(g) + 2OH−(aq) + Pb2+(aq) (2) Ni(s) + ZnO(s) → NiO(s) + Zn(s) (3) Cl2(g) + 2F−(aq) → 2Cl−(aq) + F2(g) (4) Fe3+(aq) + Ce3+(aq) → Fe2+(aq) + Ce4+(aq) (5) 2Al(s) + Cr2O3(s) → 2Cr(s) + Al2O3(s)
(5) 2Al(s) + Cr2O3(s) → 2Cr(s) + Al2O3(s)
Which of the following oxides of chlorine would you predict to be the strongest oxidizing agent? (hint: which can be reduced the most?) (1) Cl2O (2) Cl2O3 (3) Cl2O6 (4) ClO2 (5) Cl2O7
(5) Cl2O7
Predict the product(s) of the following unbalanced reaction between iodine solid and 1 M chloride ions: I2(s) + Cl-(aq) → ? (1) Cl2(g) + I-(aq) (2) HI(aq) (3) ICl4(s) (4) HCl(g) (5) NR (no reaction)
(5) NR (no reaction)
Predict the product(s) of the following unbalanced reaction: I2(s) + Cl-(aq) → ? (1) ICl4(s) (2) Cl2(g) + I-(aq) (3) HI(aq) (4) HCl(g) (5) NR (no reaction)
(5) NR (no reaction)
Which of the following reactions would you predict to be spontaneous at all temperatures (assuming ΔH°rxn does not change significantly with temperature)? (1) C6H6(l) + 3H2(g) → C6H12(l) ΔH°rxn = -207 kJ/mol (2) CaCO3(s) → CaO(s) + O2(g) ΔH°rxn = +179 kJ/mol (3) 2Ag(s) + 3N2(g) → 2AgN3(s) ΔH°rxn = +1240 kJ/mol (4) H2S(g) + 2O2(g) → H2SO4(l) ΔH°rxn = -793 kJ/mol (5) Na2CO3(s) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + CO2(g) ΔH°rxn = -834 kJ/mol
(5) Na2CO3(s) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + CO2(g) ΔH°rxn = -834 kJ/mol
Which statement is false? (1) HNO2 is a Brønsted-Lowry acid but is not a Lewis acid (2) all Brønsted-Lowry bases are also potential Lewis bases (3) Ni2+(aq) + 6H2O(l) → [Ni(H2O)6]2+(aq) is a Lewis acid-base reaction (4) H+(aq) + H2O(l) → H3O+(aq) is a Lewis acid-base reaction (5) Ni2+(aq) + CO32-(aq) → NiCO3(s) is a Lewis acid-base reaction (6) BF3 + F- → BF4- is a Lewis acid-base reaction
(5) Ni2+(aq) + CO32-(aq) → NiCO3(s) is a Lewis acid-base reaction
Predict which of the following oxoanions is the strongest base in aqueous solution at 25°C. (1) NO3− (2) HSO4− (3) ClO4− (4) HPO42− (5) PO43−
(5) PO43−
Select the false statement below regarding PbI2 (Ksp = 7.9 x 10−9) and PbCO3 (Ksp = 7.4 x 10−14). (1) PbI2 is less soluble in 1.0 M NaI than in pure water (2) the molar solubility of PbI2 can be calculated by taking the cube root of (Ksp/4) (3) PbI2 is more soluble in 1.0 M NaOH than in pure water (Kf of Pb(OH)3− = 8 x 1013) (4) PbCO3 is more soluble in 1.0 M HCl than in pure water (5) PbCO3 is more soluble in 1.0 M Pb(NO3)2 than in pure water
(5) PbCO3 is more soluble in 1.0 M Pb(NO3)2 than in pure water
Choose the stronger of each pair of acids, respectively, and explain why: a) HBrO3 or HBrO b) HBrO2 or HIO2 (1) a) HBrO3 because Br has a higher oxidation state (higher number of O atoms around it) in HBrO3 than in HBrO; b) HIO2 because I is larger than Br (2) a) HBrO because Br has a lower oxidation state (fewer number of O atoms around it) in HBrO than in HBrO3; b) HIO2 because I is larger than Br (3) All of these acids are very weak, so their relative strengths are similar (4) a) HBrO because Br has a lower oxidation state (fewer number of O atoms around it) in HBrO than in HBrO3; b) HBrO2 because Br is more electronegative than I (5) a) HBrO3 because Br has a higher oxidation state (higher number of O atoms around it) in HBrO3 than in HBrO; b) HBrO2 because Br is more electronegative than I
(5) a) HBrO3 because Br has a higher oxidation state (higher number of O atoms around it) in HBrO3 than in HBrO; b) HBrO2 because Br is more electronegative than I
Consider the following equilibrium system and select the true statement below. PCl5(g) ↔ PCl3(g) + Cl2(g) ΔH° = 92.5 kJ/mol (1) an increase in pressure at constant temperature will shift the equilibrium to the right (2) an increase in volume at constant temperature will shift the equilibrium to the left (3) Kp = Kc at constant temperature since Δn = 1 (4) an increase in temperature will decrease Kp (5) an increase in temperature at constant pressure will shift the equilibrium to the right
(5) an increase in temperature at constant pressure will shift the equilibrium to the right
Which of the following would not be a redox reaction? (1) the reaction between zinc metal and aqueous hydrochloric acid (2) the reaction that occurs when gaseous chlorine is bubbled through an aqueous potassium iodide solution (3) the combustion of a hydrocarbon in oxygen gas (4) the reaction between iron metal and sulfur to form iron(II) sulfide (5) the reaction that occurs when aqueous calcium chloride is mixed with aqueous sodium carbonate
(5) the reaction that occurs when aqueous calcium chloride is mixed with aqueous sodium carbonate