Chem Exam 3
The Ksp of silver bromide is 7.7x10⁻¹³. Calculate the molar solubility
1.7 x 10⁻⁴g/L
What is a mineral? A. A naturally occurring substance with a range of chemical composition B. A solid solution either of two or more metals, or of a metal with a nonmetal C. An ineffective conductor of electricity D. A conductor of electricity at high temperatures
A.
Which of the following reactions represents the electrolysis of Molten Sodium Chloride? 1. 2 Na⁺ (l) + 2Cl⁻ (l) → 2 Na(l) + Cl₂ (g) 2. 2 H₂O (l) → 2 H₂ (g) + O₂ (g) 3. 2 H₂O(l) + 2 Cl⁻ (aq) → H₂ (g) + Cl₂ (g) + 2 OH⁻ (aq) 4. Ca²⁺(l) + 2 Cl⁻(l) → Ca (l) + Cl₂ (g) A. 1 B. 2 C. 3 D. 4 E. 1 and 3
A.
Which one of the following is most easily reduced? A. F₂ B. Cl₂ C. Br₂ D. I₃⁻ E. F⁻
A.
Which of the following reactions represents a lead storage battery? 1. 2 H₂(g) + O₂(g) → 4 OH⁻ 2. Li (s) + CoO₂ → LiCoO₂(s) 3. Pb(s) + PbO₂(s) + 4 H⁺ (aq) + 2 SO₄²⁻ (aq) → 2 PbSO₄(s) + 2 H₂O(l) 4. Zn(s) + 2MnO₂ (s) + 2 H₂O(l) → Zn(OH)₂(s) + 2MnO(OH)(s) 5. Zn(s) + 2NH₄⁺(aq) + 2MnO₂(s) → Zn²⁺(aq) + MnO₃(s) + 2 NH₃(aq) + H₂O(l) A. 1 B. 2 C. 3 D. 4 E. 5 F. None of the above
C.
Which of the following reactions represents the electrolysis of Aqueous Sodium Chloride? 1. 2 Na⁺ (l) + 2Cl⁻ (l) → 2 Na(l) + Cl₂ (g) 2. 2 H₂O (l) → 2 H₂ (g) + O₂ (g) 3. 2 H₂O(l) + 2 Cl⁻ (aq) → H₂ (g) + Cl₂ (g) + 2 OH⁻ (aq) 4. Ca²⁺(l) + 2 Cl⁻(l) → Ca (l) + Cl₂ (g) A. 1 B. 2 C. 3 D. 4 E. 1 and 3
C.
Which of the following is NOT a principle step in the recovery of a metal from its ore 1. Preparation of the ore 2. Combusting the ore 3. Production of the metal 4. Purification of the metal
2.
Calculate [Ca²⁺],[F⁻] for a saturated CaF₂solution. Ksp = 3.9 x 10^-11 CaF₂(s) ⇌ Ca²⁺(aq) + 2F⁻(aq)
2.14 x 10⁻⁴moles/ liter
Calculate the molar solubility of silver chloride in a solution that is 6.5 x 10⁻³ M in silver nitrate. Ksp = 1.6 x 10^-10
2.5 x 10⁻⁸M
Which of the following compounds will be more soluble in acidic solution than in water? A. CuS B. AgCl C. PbSO₄
A and C
If the molar solubility of MnS is 4.47 x 10⁻²⁷ M at 298 K, what is the Ksp of MnS? A. 2 x 10⁻⁵³ B. 3.6 x 10⁻⁷⁹ C. 1 x 10⁻⁴⁰ D. 1.5 x 10⁻⁵ E. 1.8 x 10⁻¹¹
A.
In the blast furnace production of iron from its ore, the purpose of adding carbon is 1. to heat the furnace 2. to serve as a reducing agent 3. to remove silicate impurities as slag A. 1 and 2 B. 2 and 3 C. 1 and 3 D. 2 only E. 3 only
A.
In the pyrometallurgy of iron, which substance acts as the reducing agent? A. CO B. H₂O C. O₂ D. Fe₃⁺
A.
In which one of the following aqueous solutions would you expect AgCl to have the highest solubility? A. pure water B. 0.015M AgNO₃ C. 0.015 M BaCl₂ D. 0.005M NaCl E. 0.025 M KCl
A.
Solubility Equilibria: If Q < Ksp A. No precipitate forms, solid dissolves B. At equilibrium C. A precipitate forms
A.
The overall reaction shown below takes place in a lead acid battery. What substance is acting as the oxidizing agent? PbO₂(s) + Pb(s) + 2SO₄²⁻(aq) + 4H⁺(aq) → 2PbSO₄(s) + 2H₂O(l) A. PbO₂(s) B. Pb(s) C. SO₄²⁻ D. H⁺ E. H₂O(l)
A.
To become a more efficient werewolf hunter Edward decides to have his dagger coated with silver. If he needs a coating of 2.5 grams of silver on his dagger, how long must he run a current of 0.85 amps through his dagger while submerged in a solution of 1.0 M AgNO₃? A. 43.9 minutes B. 294 minutes C. 31.7 minutes D. 12.4 minutes E. 4700 minutes
A.
What is the equilibrium constant for the following reaction? AgI(s) + 2CN⁻(aq) ⇌ Ag(CN)₂⁻(aq)+ I⁻(aq) Ksp for AgI = 8.3 x 10⁻¹⁷ and Kf for Ag(CN)₂⁻ = 1.0 x 10²¹ A. 8.3 x 10⁴ B. 1.2 x 10⁻⁵ C. 1.0 x 10⁻²¹ D. 8.3 x 10⁻¹⁷ E. 1.2 x 10¹⁶
A.
What is the overall cell potential of a Lithium-Ion battery? A. 3.4 V B. 1.5 V C. 2 V D. 1.23V
A.
Which of the following processes is known as zinc-plating? A. Galvanization B. Passivation C. Patina D. Corrosion
A.
Which of the following reactions represents a fuel cell battery? 1. 2 H₂(g) + O₂(g) → 4 OH⁻ 2. Li (s) + CoO₂ → LiCoO₂(s) 3. Pb(s) + PbO₂(s) + 4 H⁺ (aq) + 2 SO₄²⁻ (aq) → 2 PbSO₄(s) + 2 H₂O(l) 4. Zn(s) + 2MnO₂ (s) + 2 H₂O(l) → Zn(OH)₂(s) + 2MnO(OH)(s) 5. Zn(s) + 2NH₄⁺(aq) + 2MnO₂(s) → Zn²⁺(aq) + MnO₃(s) + 2 NH₃(aq) + H₂O(l) A. 1 B. 2 C. 3 D. 4 E. 5 F. None of the above
A.
Which one of the following substances when added to a saturated solution of AgCl will cause it to precipitate out as a solid? A. HCl B. HNO₃ C.NH₃ D. H₂O E. None of the above
A.
Which type of cell is used for the electrolysis of molten NaCl? A. Downs cell B. Galvanic cell C. Haber cell D. Fuel cell
A.
The most common batteries are which of the following? A. dry cell batteries B. lithium-ion batteries C. alkaline batteries D. lead storage batteries E. fuel cell batteries
A. and C.
Which of the following statements concerning the lead storage battery is false? A. The electrolyte present is aqueous H₂SO₄ B. During chargine, PbO₂is formed at one electrode C. In winter, a charged battery is more likely to freeze than an uncharged one D. During discharge, PbSO₄is formed at both electrodes E. The amount of charge present in the battery can be guessed by measuring the density of the electrode
C.
Which of the following statements is true regarding the problems with fuel cells? A. They are less efficient than combustion engines B. They are noisy, and create large amounts of pollution C. They are expensive to run for long periods of time D. They do not have any notable application in science or industry
C.
Which one of the following compounds forms a saturated solution that will increase in solubility if the pH is decreased? A. AgBr B. AgCl C. AgF D. Ag₂SO₄ E. AgI
C.
Which one of the following statements concerning the lead storage battery is false? A. The electrolyte present is aqueous H₂SO₄ B. During charging, PbO₂ is formed at one electrode C. In winter, a charged battery is more likely to freeze than an uncharged one D. During discharge, PbSO₄ is formed at both electrodes E. The amount of charge present in the battery can be guessed by measuring the density of the electrolyte
C.
Which one of the following statements is true about the equilibrium constant for a reaction if ΔG° for the reaction is negative? A. K = 0 B. K = 1 C. K > 1 D. K < 1 E. K < 0
C.
Which of the following about the dissociation of an ionic solid in water is false? A. The solution may be unsaturated B. The solution may be supersaturated C. The solution may be saturated D. All three are true
D.
Which of the following reactions represents an alkaline battery? 1. 2 H₂(g) + O₂(g) → 4 OH⁻ 2. Li (s) + CoO₂ → LiCoO₂(s) 3. Pb(s) + PbO₂(s) + 4 H⁺ (aq) + 2 SO₄²⁻ (aq) → 2 PbSO₄(s) + 2 H₂O(l) 4. Zn(s) + 2MnO₂ (s) + 2 H₂O(l) → Zn(OH)₂(s) + 2MnO(OH)(s) 5. Zn(s) + 2NH₄⁺(aq) + 2MnO₂(s) → Zn²⁺(aq) + MnO₃(s) + 2 NH₃(aq) + H₂O(l) A. 1 B. 2 C. 3 D. 4 E. 5 F. None of the above
D.
Which of the following reactions will occur spontaneously under standard conditions? 1. Cl₂ (g) + 2 Br⁻ → 2 Cl⁻ + Br₂ 2. Cl₂ (g) + 2 I⁻ → 2 Cl⁻ + I₂ 3. I₂ + 2 Br⁻ → 2 I⁻ + Br₂ A. 1 only B. 2 only C. 3 only D. 1 and 2 only E. 1, 2 and 3
D.
Which one of the following substances when added to a saturated solution of Pb(OH)₂will decrease the solubility of Pb(OH)₂? A. NaNO₃ B. H₂O C. HNO₃ D. NaOH E. None of the above
D.
In the electrolysis of molten KBr, what product is formed at the cathode? A) K⁺ ions B) KBr crystals C) Br⁻ ions D) Br₂gas E) K(s)
E)
The solubility of PbCl₂is 1.6 x 10⁻² M. What is the Ksp of PbCl₂ A) 1.6 x 10⁻² B) 3.1 x 10⁻⁷ C) 4.1 x 10⁻⁶ D) 5.0 x 10⁻⁴ E) 1.6 x 10⁻⁵
E)
Which of the following substances cannot be corroded by oxygen? A. Fe B. Al C. Au D. Cu E. Ag
C.
Which of the following substances will not be more soluble in acidic solutions? A. Fe(OH)₃ B. Ca₃(PO₄)₂ C. AgCl D. CaF₂ E. Ag₂CO₃
C.
Iron objects such as storage tanks and underground pipelines can be protected from corrosion by connecting them through a wire to a piece of which metal? A. Pb B. Ag C. Sn D. Mg E. Cu
D.
T/F: A salt is sparingly soluble (insoluble) if its concentration in aqueous solution is > 0.1 M
False
T/F: Iron extracted by a blast furnace contains many impurities called pig iron (cast iron)
True
The strongest reducers are... a. easily oxidized b. easily reduced
a.
In the preliminary treatment of an ore, the desired mineral is separated from waste minerals called what? a. floaters b. ores c. precipitates d. gangue
d.
T/F: Properly designed fuel cells may be as much as 70% efficient, which is about twice as efficient as an internal combustion engine.
True
T/F: Steel is an alloy of iron
True
T/F: The electrolysis of Molten Sodium Chloride is a major industrial source of pure sodium metal and chlorine gas
True
T/F: The formation of rust requires oxygen and water
True
T/F: The greater the potential difference between the two half cell reactions, the greater the voltage of the cell
True
T/F: The reaction of iron rusting can only occur in acidic medium
True
T/F: The slag from the pyrometallurgy of iron can be used to make cement and other building materials
True
T/F: When the sign of the enthalpy and entropy are identical, the sign of the free energy depends on the temperature
True
T/F: When you go from non-spontaneous to spontaneous, ΔG changes from + to -
True
T/F: When ΔH is negative and ΔS is positive, ΔG is negative and is spontaneous at all temperatures
True
T/F: When ΔH is positive and ΔS is positive, ΔG is spontaneous at high temperatures but not at low temperatures
True
T/F: ΔG refers to a reaction at constant T and P
True
What is the concentration of Zn²⁺ when the cell based on the following reaction has a potential of 1.30 V at 25°C? Zn + Cu²⁺(1.0 x 10⁻⁵ M) → Zn²⁺ + Cu a. 1.0 M b. 1.7 x 10⁻¹² M c. 4.4 x 10⁻⁸⁷ M d. 4.1 x 10⁻⁹ M e. 60.2 M
b.
What is the oxidizing agent in this cell? 2 Ag⁺(1.0 M) + Ni(s) → Ni²⁺ (1.0 M) + 2 Ag(s) a. Ag b. Ag⁺ c. Ni²⁺ d. Ni e. None of the above
b.
Which is the best reducing agent of the following? a. Cl⁻ b. Fe c. Fe³⁺ d. Fe²⁺ e. Cl₂
b.
Which of the following are true for a voltaic cell? I. ΔG° > 0 II. Oxidation will occur at the anode III. At equilibrium, E°cell will equal 0 a. I only b. II only c. I and II d. II and III e. I and III
b.
Which of the following does not exist in a voltaic cell? a. Electrodes b. Galvanized metal c. Electrolytes d. Salt bridge
b.
Which reaction below occurs at the cathode of a lead storage battery? x: Pb(s) + SO₄²⁻(aq) → PbSO₄²⁻ + 2e⁻ xx : PbO₂(s) + 4 H⁺(aq) + SO₄²⁻(aq) + 2e⁻ → PbSO₄(s) + 2H₂O(l) a. x b. xx
b.
Why are secondary batteries such as the lead-acid battery and the nickel-metal-hydride battery rechargeable, while alkaline dry-cell batteries and regular alkaline flashlight batteries are not rechargeable? a. The electrolyte in the non-rechargeable batteries is not concentrated enough b. Bot the reactants and the products in the rechargeable batteries are in the solid state c. The voltage in the non-rechargeable batteries is too low d. The hydroxide ions in alkaline batteries interfere with the recharging process e. An expensive catalyst would be required to charge the alkaline batteries
b.
A voltaic cell has the following reaction Al (s) + 3 Ag⁺(aq) → Al³⁺(aq) + Ag(s) 1. What will happen to the cell emf (Ecell) if AgNO₃is added to the cathode compartment increasing the quantity of Ag⁺, but not changing its concentration? a) Ecell will increase b) Ecell will decrease c) This will have no effect
c)
A voltaic cell has the following reaction Al (s) + 3 Ag⁺(aq) → Al³⁺(aq) + Ag(s) 1. What will happen to the cell emf (Ecell) if the size of the Al electrode is increased? a) Ecell will increase b) Ecell will decrease c) This will have no effect
c)
Arrange the following oxidizing agents in order of increasing oxidizing power: I₂, IO₃⁻, F₂, PbO₂, Na⁺ , Zn²⁺ a. I₂ < Zn²⁺ < IO₃⁻ < PbO₂ < Na⁺ < F₂ b. F₂ < PbO₂ < IO₃⁻ < I₂ < Zn²⁺ < Na⁺ c. I₂ < IO₃⁻ < PbO₂ < F₂ < Zn²⁺ < Na⁺ d. Na⁺ < Zn²⁺ < I₂ < PbO₂ < F₂ e. I₂ < IO₃⁻ < PbO₂ < F₂ < Na⁺ < Zn²⁺
d.
Calculate the change in Gibbs Free Energ for the following reaction: SO₂(g) + 2H₂(g)→S(s) + 2H₂O(g) a. +71.83 kJ b. -528.94 kJ c. +757.54 kJ d. -156.7 kJ e. -38.5 kJ
d.
What does the salt bridge do? a. It is where reduction takes place b. It is where oxidation takes place c. It acts as a conductor for non-metals d. It balances and maintains charge neutrality
d.
Zn(s) + 2H⁺ → Zn²⁺ + H₂ What is the oxidation state of Zn²⁺? a. 0 b. +1 c. -2 d. +2
d.
T/F: A large Keq value means that the reaction is spontaneous
True
T/F: A salt is very soluble if its concentration is > 0.1 M
True
T/F: A species which is higher and to the left on the table of standard reduction potentials will spontaneously oxidize a species that is lower to the right in the table
True
T/F: A useful method for separating waste material from ore is called floatation
True
T/F: Alkaline batteries are more expensive than dry cell batteries and offer superior performance and shelf life
True
T/F: At equilibrium point, ΔG = 0 for inter-converting reactants ↔ products. This does NOT mean that ΔG° = 0
True
T/F: Atoms tend to lose or gain electrons in order to achieve a complete octet
True
T/F: Because of its good conductivity, copper is used to make electrical wiring
True
T/F: Before Hall invented his mechanism to electrolyze aluminum, Aluminum oxide melted at 2000°C and was impractical to electrolyze because of that
True
T/F: Concerning the lead storage battery during charging, PbO₂is formed at one electrode
True
T/F: Concerning the lead storage battery, during discharge, PbSO₄is formed at both electrodes
True
T/F: Concerning the lead storage battery, the amount of charge present in the battery can be guessed by measuring the density of the electrode
True
T/F: Concerning the lead storage battery, the electrolyte present is aqueous H₂SO₄
True
T/F: Eac cell of a lead storage battery has a lead anode and a cathode made of lead dioxide (PbO₂) packed on a metal plate
True
T/F: Electrolysis is used to purify copper which can achieve a purity of 99.5 %. In this process, copper acts as the anode and the cathode
True
T/F: Electrons cannot swim in a voltaic solution, they can only move through the external wire
True
T/F: Entropy always increases during evaporation and melting
True
T/F: Free energy is released for all exothermic reactions that have positive S values
True
T/F: If ΔH and ΔS have the same sign, then temperature will decide whether the reaction is spontaneous or non-spontaneous
True
T/F: In the electrolysis of aqueous sodium sulfate Na₂SO₄, water is the reactant which will be reduced and oxidized at both electrodes
True
T/F: Lithium-ion batteries are used in labtops, cell phones and digital cameras because they can be charged hundreds of times
True
T/F: Many biological reactions have positive ΔG° value, making the reaction non-spontaneous
True
T/F: Not all exothermic reactions are spontaneous
True
The strongest oxidizers are.... a. easily oxidized b. easily reduced
b.
How many Faradays will be required to reduce 1 mole of Cr₂O₇²⁻ to Cr²⁺? A. 8 B. 6 C. 4 D. 3 E. 2
A.
Which of the following could be utilized to create a "sacrificial anode" to prevent the oxidation of iron? A) Zn (s) B) Al(OH)₃ C) Ag (s) D) Ag⁺(aq) E) Cd (s)
A)
Calculate the value of ΔG° (in kJ/mole) for this reaction at 25°C. N₂(g) + 3H₂(g) → 2NH₃(g) K = 5.0 x 10⁸ A. -50 B. -25 C. -4.2 D. 50 E. 22
A.
Consider an electrochemical cell based on the reaction: 2H⁺(aq) + Sn(s) → Sn²⁺(aq) + H₂(g) Which one of the following actions would increase the measured cell potential? A. decreasing the pH in the cathode department B. Increasing the mass and the surface area of the Sn eletrode C. Increasing the [Sn²⁺] in the anode compartment D. Increasing the pressure of hydrogen gas in the cathode compartment E. All of the above will increase the cell potential
A.
Consider an electrochemical cell based on the reaction: 2H⁺ + Sn ⇌ Sn²⁺ + H₂ Which one of the following actions would increase the measured cell potential? A. Decreasing the pH in the cathode department B. Increasing the mass and surface area of the Sn electrode C. Increasing the [Sn²⁺] in the anode compartment D. Increasing the pressure of hydrogen gas in the cathode compartment E. All of the above
A.
Consider the following reaction: A + B → C + D This reaction is always spontaneous when Δ H is ____ and ΔS is ____ A. negative and positive B. positive and negative C. negative and negative D. positive and positive
A.
Consider the reaction (demonstrated in class) which occurs when a balloon filled with H₂(g) and O₂(g) is ignited. The sings of ΔH, ΔS, and ΔG would be: 2H₂(g) + O₂(g) → 2H₂O(g) A. - ; - ; - B. - ; - ; + C. - ; + ; - D. + ; - ; - E. + ; + ; +
A.
Contact of a dental filling with aluminum foil causes a momentary sharp tooth pain. Dental amalgam is a mixture of Ag₂Hg₃, Ag₃Sn and Sn₈Hg. The standard reduction potentials for these are: E(Hg₂²⁺/Ag₂Hg₃) = 0.85 V; E (Sn²⁺/Ag₃Sn) = -0.05V; E (Sn²⁺/Sn₈Hg) = -0.13 V. Which of the following statements is false for this electrochemical reaction: A. aluminum acts as the cathode B. substances in the dental amalgam act as the cathode C. aluminum will be oxidized D. the most likely species to be reduced is Hg₂²⁺ E. none of the above is false
A.
One of the ores containing copper is known as chalcocite. What is the oxidation state of copper in Cu₂S? A. 0 B. +1 C. +2 D. +3 E. +4
B
Which of the following metals is NOT considered to be a good electrocatalyst? A. Pt B. Au C. Ni D. Rh
B
For this reaction, which of the following statements is true? 2 Cr (s) + 3 Pb²⁺(aq) → 3 Pb (s) + 2 Cr³⁺(aq) I. The reaction is spontaneous ii. K > 1 iii. ΔG > 0 iv. E°cell > 1 A) iii only B) I, and ii only C) I and iii only D) ii, iii and iv only E) all of the above
B)
Given the following information, which of the following substances is the strongest Lewis base? Kf for Ag(CN)₂is 1 x 10²¹ Kf for Ag(S₂O₃)₂³⁻ is 2.9 x 10¹³ A) Ag⁺ B) CN⁻ C) S₂O₃³⁻ D) Ag(CN)₂⁻ E) Ag(S₂O₃)₂³⁻
B)
How many electrons are needed to balance the following half reaction in acid solution? MnO₄⁻(aq) → Mn²⁺(aq) A) 3 B) 5 C) 2 D) 1 E) 4
B)
If ΔG° for the reaction is greater than zero, then which of the following must be true? A) K > 1 B) K < 1 C) K = 1 D) More info is needed E) K = 0
B)
A current of 0.452 A is passed for 1.50 hour through an electrolytic cell containing molten MgCl₂. The quantity of Mg plated out will be: A. 0.154 g B. 0.306 g C. 0.614 g D. 1.540 g E. None of the above
B.
AgCl is a sparingly soluble salt, with a solubility of about 10⁻⁵ in pure water. Why does adding KCN increase the solubility of AgCl? A. CN⁻ is a base, which increases the pH to form soluble AgOH B. CN⁻ reacts with Ag⁺ to make a soluble complex C. CN⁻ reacts with Ag⁺ to make a sparingly soluble salt with a larger Ksp than AgCl D. CN⁻ reduces Ag⁺ to Ag metal E. K⁺ reacts with Cl⁻ to form solid KCl
B.
Calculate the [Cr⁺³] in equilibrium with Cr(OH)₄⁻(aq) when 0.010 mole of Cr(NO₃)₃is dissolved in a liter of solution buffered at a pH of 7.3 Kf for Cr(OH)₄⁻ (aq) is 8.0 x 10²⁹ A.1.98 x 10⁻³ M B. 7.88 x 10⁻⁶M C. 3.05 x 10⁻⁸M D. 1.60 x 10²³ M E. 2.00 x 10⁻⁷M
B.
Consider a voltaic cell based on the following reaction Pb + 2H⁺ + SO₄²⁻ → PbSO₄+ H₂ E⁰= +0.36 V The following changes are made in an attempt to increase the voltage of the cell (1) The area of the Pb electrode is increased (2) The [H⁺] is increased (3) The pressure of H₂ is increased The change(s) which would increase the cell voltage is (are) A. 1, 2, and 3 B. 2 only C. 3 only D. 1 only E. None of the above
B.
Which of the following metals will not provide cathodic protection to prevent corrosion of iron? A. Zn B. Mg C. Cu D. Al E. Cr
C.
Consider a voltaic cell based upon the following reaction Pb(s) + 2H⁺ + SO₄²⁻ → PbSO₄(s) + H₂(g) E°= 0.36 V The following changes are made in an attempt to increase the voltage of the cell: 1. The area of the Pb electrode is increased 2. The [H⁺] is increased 3. The pressure of H₂ is increased The change(s) which would increase the cell voltage is (are) A. 1, 2, and 3 B. 2 only C. 3 only D. 1 only E. None of the above changes will have an effect on the cell voltage
B.
Dissolving ammonium chloride in water lowers the temperature of the surroundings as shown on a thermometer. For this dissolution process: A. ΔH is negative and ΔS is negative B. ΔH is positive and ΔS is positive C. ΔH is negative and ΔS is positive D. ΔH is positive and ΔS is negative E. ΔH is positive and ΔS is zero
B.
Electrolysis is used commercially in the Hall Process for production of pure aluminum metal at high temperatures from Al³⁺. The half reactions are shown below; the anodes are made from graphite and the cathode is aluminum. Which statement about the process is FALSE? C(s) + 2 O²⁻(l) → CO₂ (g) + 4 e⁻ 3 e⁻ + Al³⁺ (molten cryolite) → Al (l) A. The anode is the positive electrode and the cathode is the negative electrode B. The aluminum reduction process is spontaneous C. The cell potential is negative D. Reduction occurs at the cathode E. Positive ions migrate to the cathode
B.
For the electrolysis of aqueous NaCl: 1) Na⁺(aq) + e⁻ → Na(s) E° = −2.71 V 2) 2H₂O(l) + 2e⁻→ H₂(g) + 2OH⁻(aq) E° = −0.42 V 3) 2Cl⁻(aq) → Cl₂(g) + 2e⁻ E° = −1.36 V 4) 2H₂O(l) → O₂(g) + 4H⁺(aq) + 4e⁻ E° = −0.83 V Which reaction will occur at the cathode? A. 1 B. 2 C. 3 D. 4 E. 3 and 4
B.
In a lecture demonstration, an aqueous solution of Pb(NO₃)₂ was electrolyzed at inert Pt wire electrodes. What is true about the pure metallic Pb (s) ? A. Pb (s) was deposited on the anode B. Pb (s) was deposited on the cathode C. Pb (s) remained in the electrolyte (in solution) D. Pb (s) was collected in the anode sludge E. Pb (s) was collected in the cathode sludge
B.
Most metallurgical processes involve... A. hydrometallurgy B. pyrometallurgy C. electrometallurgy D. oxometallurgy
B.
Solubility Equilibria: If Q =Ksp A. No precipitate forms, solid dissolves B. At equilibrium C. A precipitate forms
B.
The following chemical reactions occur in a blast furnace during the refining of iron ore: 1. 2C + O₂→ 2CO + heat 2. heat + C + H₂O → CO + H₂ 3. Fe₃O₄ + 4CO → 3Fe + 4CO₂ 4. Fe₃O₄+ 4H₂→ 3Fe + 4H₂O Which reaction is responsible for cooling the furnaces? A. Reaction 1 B. Reaction 2 C. Reaction 3 D. Reaction 4 E. Reactions 3 and 4
B.
The use of electric energy to drive a non-spontaneous chemical reaction is called: A. Galvanization B. Electrolysis C. Reduction D. Oxidation E. Alchemy
B.
Under normal operating conditions, how many volts of electricity are produces by the lead acid battery? A. 1.5 V B. 12 V C. 3.4 V D. 15 V E. 2 V
B.
What is the cell potential of a dry cell battery? A. 3.4 V B. 1.5 V C. 2 V D. 1.24 V
B.
What is the coefficient of the sulfate ion when the following reaction is balanced? ClO⁻ + S₂O₃ → Cl⁻ + SO₄²⁻ A. 1 B. 2 C. 3 D. 4 E. 5
B.
When an aqueous solution that is 1 M each in HCl, CuCl₂, and CoBr₂is electrolyzed, the elemental products formed initially at the cathode and the anode are, respectively: A. Zn(s) and Cl₂(g) B. Cu(s) and Br₂(g) C. H₂(g) and Cl₂(g) D. Zn(s) and Br₂(g) E. H₂(g) and Br₂(g)
B.
When ΔG is > 0, the reaction is... A. Spontaneous B. Not Spontaneous C. At equilibrium
B.
Which of the following decreases when solid Ba(OH)₂is added to a saturated solution of BaCO₃(Ksp = 5.1 x 10⁻⁹) A. [Ba²⁺] B. [CO₃²⁻] C. [OH⁻] D. pH E. None of the above
B.
Which of the following metals can be used to provide cathodic protection to prevent corrosion of iron? A. Co B. Al C. Sn D. Cd E. None of the above
B.
Which of the following processes is used for the electrometallurgy of aluminum? A. Downs B. Hall C. Faraday D. Haber
B.
Which of the following reactions represents a lithium-ion battery? 1. 2 H₂(g) + O₂(g) → 4 OH⁻ 2. Li (s) + CoO₂ → LiCoO₂(s) 3. Pb(s) + PbO₂(s) + 4 H⁺ (aq) + 2 SO₄²⁻ (aq) → 2 PbSO₄(s) + 2 H₂O(l) 4. Zn(s) + 2MnO₂ (s) + 2 H₂O(l) → Zn(OH)₂(s) + 2MnO(OH)(s) 5. Zn(s) + 2NH₄⁺(aq) + 2MnO₂(s) → Zn²⁺(aq) + MnO₃(s) + 2 NH₃(aq) + H₂O(l) A. 1 B. 2 C. 3 D. 4 E. 5 F. None of the above
B.
Which of the following reactions represents the electrolysis of Water? 1. 2 Na⁺ (l) + 2Cl⁻ (l) → 2 Na(l) + Cl₂ (g) 2. 2 H₂O (l) → 2 H₂ (g) + O₂ (g) 3. 2 H₂O(l) + 2 Cl⁻ (aq) → H₂ (g) + Cl₂ (g) + 2 OH⁻ (aq) 4. Ca²⁺(l) + 2 Cl⁻(l) → Ca (l) + Cl₂ (g) A. 1 B. 2 C. 3 D. 4 E. 1 and 3
B.
Which of the following solutions will form solid precipitate of AgSO₄? The Ksp of AgSO₄ is 1.5 x 10⁻⁵? A. 5 x 10⁻⁵ moles of Na₂SO₅ added to 100 ml of 0.05 M AgNO₃ solution B. 5 x 10⁻³ moles of Na₂SO₅ added to 100 ml of 0.05 M AgNO₃ solution C. 5 x 10⁻⁷ moles of Na₂SO₅ added to 100 ml of 0.05 M AgNO₃ solution D. 1 x 10⁻⁶ moles of Na₂SO₅ added to 100 ml of 0.05 M AgNO₃ solution E. All of the above
B.
Which one of the following elements is most likely to be found as the free elemental metal in nature? A. Ca B. Au C. Al D. Fe E. Zn
B.
What is the value of Keq for the following equilibrium? (Kf for Ag(CN)₂⁻ is 1 x 10²¹ and Kf for Ag(S₂O₃)₂³⁻ is 2.9 x 10¹³ Ag(S₂O₃)₂³⁻ + 2 CN⁻ ⇌ Ag(CN)₂⁻ + 2 S₂O₃²⁻ A) 5.1 x 10¹² B) 2.9 x 10⁻⁸ C) 3.5 x 10⁷ D) 5 x 10³⁷ E) 2.4 x 10¹² F) 1 x 10²¹
C)
Which of the following is the strongest reducing agent? A) Pb(s) B) Fe(s) C) Al(s) D) Ag(s) E) Sn(s)
C)
A Zn²⁺ solution is electrolyzed using a current of 0.6 amps. What mass of Zn (s) is plated out after 5 hours? (The atomic weight of Zn = 65.4 g/mole) A. 6.10 x 10⁻² g B. 7.32 g C. 3.66 g D. 1.83 g E. 5.60 x 10⁻² g
C.
A mineral deposit concentrated enough to allow economical recovery of a desired metal is known as a: A. Conductor B. Semi-conductor C. Ore D. Mineral
C.
For the electrolysis of aqueous NaCl: 1) Na⁺(aq) + e⁻ → Na(s) E° = −2.71 V 2) 2H₂O(l) + 2e⁻→ H₂(g) + 2OH⁻(aq) E° = −0.42 V 3) 2Cl⁻(aq) → Cl₂(g) + 2e⁻ E° = −1.36 V 4) 2H₂O(l) → O₂(g) + 4H⁺(aq) + 4e⁻ E° = −0.83 V Which reaction will occur at the anode? A. 1 B. 2 C. 3 D. 4 E. 3 and 4
C.
Given that the value of Ka for NH₄⁺ is 5.6 x 10⁻¹⁰ at 298 K. What is the Gibbs Free Energy of the acid hydrolysis when [NH₄⁺] = 0.4 M, [NH₃] = 0.2 M and [H⁺] = 0.004 M at the same temperature? A. +0.813 kJ/mole B. -15.4 kJ/mole C. +37.4 kJ/mole D. +53.8 kJ/mole E. +3.14 kJ/mole
C.
How many Faradays are required to reduce 1 mole of MnO₄⁻ to MnO₂? A. 1 B. 2 C. 3 D. 4 E. 5
C.
In the pyrometallurgy of iron, which substance removes the slag? A. H₂O B. NaOH C. CaCO₃ D. SiO₂
C.
Processes used to reduce metal ores or to refine metals that are based on the process of electrolysis are collectively referred to as.... A. pyrometallurgy B. hydrometallurgy C. electrometallurgy D. calcination E. roasting
C.
Solid NaBr is slowly added to a solution that is 0.010 M in Cu⁺ and 0.010 M in Ag⁺. Which of the following statements is true? (Ksp for CuBr = 5.3 x 10⁻⁹; Ksp for AgBr = 5.0 x 10⁻¹³) A. NaBr will precipitate first B. CuBr will precipitate first C. AgBr will precipitate first D. No precipitate will form E. None of the above
C.
Solubility Equilibria: If Q >Ksp A. No precipitate forms, solid dissolves B. At equilibrium C. A precipitate forms
C.
The cathode and the anode of a lead storage battery are immersed in which of the following electrolytes? A. HCl B. HSbF₆ C. H₂SO₄²⁻ D. HBrO₄ E. None of the above
C.
The hydrometallurgical process used in refining gold ore entails converting metallic gold to a water-soluble complex. What is the formula for this complex? A. Au(NH₃)₂⁺ B. Au(NH₃)₄⁻ C. Au(CN)₂⁻ D. Au(CO)₄²⁻ E. Au(CO)₄⁺
C.
The solubility of LaF₃ is 1.8 x 10⁻³ g/L. Given that the molecular weight of LaF₃ is 196 g/mole, what is the value of Ksp? A. 4 x 10⁻¹⁵ B. 8 x 10⁻¹⁶ C. 2 x 10⁻¹⁹ D. 7 x 10⁻²¹ E. 3 x 10⁻²⁷
C.
The standard potential for the rusting of iron is: A. 1.34 V B. 2 V C. 1.67 V D. 1.5 V
C.
What is one of the differences between a voltaic cell and an electrolytic cell? A. In an electrolytic cell, an electric current is produced by a chemical reaction B. In an electrolytic cell, electrons flow towards the anode C. In an electrolytic cell, a nonspontaneous reaction is forced to occur D. In an electrolytic cell, O₂gas is always produced at the cathode E. In an electrolytic cell, only non-aqueous electrolyte solutions can be used
C.
What is the difference between the spontaneous chemical reactions in a dry cell battery and an alkaline battery? A. There is no difference B. Alkaline batteries do not reduce manganese dioxide C. The reaction in an alkaline battery takes place in a basic medium D. Alkaline batteries have a moist paste of ZnCl₂ and NH₄Cl
C.
When ΔG is < 0, the reaction is... A. At equilibrium B. Not spontaneous C. Spontaneous
C.
When ΔG is = 0, the reaction is, A. Spontaneous B. Not spontaneous C. At equilibrium
C.
Which battery is sometimes referred to as "the battery of the future"? A. Fuel Cells B. Dry Cells C. Lithium-Ion Batteries D. Lead Storage Batteries E. Alkaline Batteries
C.
Which of the following does not affect the solubility of ionic compounds? A. Common Ion effect B. pH C. Temperature D. Formation of complex ions
C.
Which of the following is a difference between a voltaic cell and an electrolytic cell? A. In an electrolytic cell, an electric current is produced by a chemical reaction B. In an electrolytic cell electrons flow towards the anode C. In an electrolytic cell a non-spontaneous reaction is forced to occur D. In an electrolytic cell, O₂ gas is always produced at the cathode E. In an electrolytic cell, only non- aqueous electrolyte solutions can be used
C.
Which of the following is not a noble metal? A. Au B. Pt C. Hg₂ D. Ag
C.
Which of the following is not a procedure used to purify metals? A. Distillation B. Electrolysis C. Galvanization D. Zone Refining
C.
Calculate ΔG° for the auto-ionization of water at 25°C. A) -2.91 kJ/ mole B) 14 kJ / mole C) -34.7 kJ/mole D) 79.8 kJ/mole E) -14 kJ/mole
D)
For the reaction below, ΔH° is +137 kJ/mole and ΔS° is + 120 J/K-mole. Which statement is true? C₂H₆ (g) → C₂H₄(g) + H₂(g) A) The reaction is spontaneous only at low temperature B) The reaction is spontaneous at all temperatures C) The reaction is non-spontaneous at all temperatures D) The reaction is spontaneous only at high temperature E) The reaction is exothermic
D)
If a cylinder of aluminum is attached to an iron pipe by a wire, which metal will corrode first? A) They would both corrode at the same rate. B) iron C) Neither metal would corrode D) aluminum
D)
Nittanium (Nt) happens to be a rather useful oxidizing agent. After being placed in a voltaic cell with Li, the standard emf was found to be E° = 4.00 V. If the concentration of lithium ions is 2.0 M at 298K, what is the concentration of Nt²⁺ in the cell if the emf is found to be E = 3.88 V? A) 1.8 x 10⁻⁴M B) 2.5 x 10⁻⁶ M C) 5.0 x 10² M D) 3.4 x 10⁻⁴M E) 1.0 x 10⁴M
D)
What is the value for Keq for the following equilibrium? Kf for [Fe(CN)₆]³⁻ is 1 x 10⁴² [Fe(CN)₆]³⁻ (aq) ⇌ Fe³⁺(aq) + 6CN⁻ (aq) A) -1 x 10⁴² B) 1 x 10²¹ C) 1 x 10⁴² D) 1 x 10⁻⁴² E) 1 x 10⁸⁴
D)
A flask containing a mixture of solids given in the equation below was placed on a board in a puddle of water. When the salts were mixed, a reaction occurred and as a result the water froze causing the flask to freeze to the board. Ba(OH)₂8H₂O(s) + 2NH₄SCN(s) → Ba(SCN)₂(aq) + 2NH₃(g) + 10H₂O(l) For this reaction: A. ΔH and ΔS are both zero B. ΔH is positive and ΔS is negative C. ΔH is negative and ΔS is positive D. ΔH is positive and ΔS is positive E. ΔH is negative and ΔS is negative
D.
A solution contains a mixture of three anions with the following concentrations: 0.20 M CrO₄²⁻, 0.10 M CO₃²⁻ , 0.010 M Cl⁻. If a dilute AgNO₃ solution is slowly added to the solution, which solid compound will be the first to precipitate? A. AgNO₃ B. Ag₂CrO₄ (Ksp = 1.2 x 10⁻¹²) C. Ag₂CO₃ (Ksp = 8.1 x 10⁻¹²) D. AgCl (Ksp = 1.8 x 10⁻¹⁰) E. They will precipitate at the same time
D.
Consider the following reaction occuring in an automobile engine: 2 C₈H₁₈(l) + 25 O₂(g) → 16 CO₂(g) + 18 H₂O(g) The signs of ΔH, ΔS, and ΔG would be: A. - ; + ; + B. + ; - ; + C. + ; + ; - D. - ; + ; - E. + ; + ; +
D.
Electrodes in fuel cells serve two purposes: 1. They serve as electrical conductors and 2. They provide the necessary surfaces for the initial decomposition of the molecules into atomic species. What special name is given to these electrodes? A. Galvanic electrodes B. Fuel cell agents C. Alkaline electrodes D. Electrocatalysts
D.
Hall used a substance called molten cryolite to lower the melting point of aluminum oxide, allowing the mass industrial processing of aluminum. What is the formula for molten cryolite? A. Al₂O₃ B. NaAl(SO₄) C. LiCO₃⁻ D. Na₃AlF₆
D.
How many grams of Ca metal would be produced by the electrolysis of molten CaBr₂using a current of 30.0 amp for 10.0 hours? A. 22.4 g B. 452 g C. 0.0622 g D. 224 g E. 5.60 g
D.
What is hydrogen gas converted to when it is used to reduce an ore in a blast furnace? A. ammonia B. helium C. hydrogen peroxide D. water E. hydroxide
D.
What is mettalurgy? A. The study of reaction rates B. The study of energy transformation within a chemical process C. The science of creating transistors D. The science of separating materials from their ores and of compounding alloys
D.
What is slag? A. Another term for a blast furnace B. The minerals separated from ore in the preliminary step of metallurgy C. The type of carbon used to reduce iron in the blast furnace D. The mixture of calcium silicate and calcium aluminate the remains molten at the furnace temperature
D.
What is the coefficient of the hypochlorite ion when the following reaction is balanced? ClO⁻ + S₂O₃ → Cl⁻ + SO₄²⁻ A. 1 B. 2 C. 3 D. 4 E. 5
D.
What is the concentration of free Cadmium (II) ion in solution when the total Cd(II) concentration (free ions + complex ions) is 0.20 M, and the solution also contains 2.0 M sodium cyanide (NaCN) ? (Kf for Cd(CN)₄²⁻ = 7.1 x 10¹⁶) A. 2.0 M B. 0.20 M C. 1.4 x 10⁻¹⁷ M D. 1.8 x 10⁻¹⁹ M E. 3.1 x 10⁻²⁵ M
D.
What is the overall cell potential of a Fuel Cell battery? A. 3.4 V B. 1.5 V C. 2 V D. 1.23V
D.
Which metals can only be made in pure form via electrolysis? I. Group I metals II. Group II metals III. Transition metals A. I only B. II only C. III only D. I an II E. I and III
D.
The spontaneous reaction below occurs in a voltaic cell. Which of the following statements about this cell is true? Pb²⁺(aq) + Zn(s) → Pb(s) + Zn²⁺(aq) A) The concentration of Pb²⁺ ions in the cathodic department will increase as the reaction proceeds B) Zn²⁺ ions migrate towards the anode C) Zn²⁺ is reduced at the cathode D) The Zn electrode is positive with respect to the Pb electrode E) Electrons flow in the external circuit from the Zn to the Pb electrode F) The zinc electrode will gain mass as the reaction proceeds G) The cell potential is -0.637 V
E)
The standard reduction potential of Na⁺(aq) is -2.71 V. In the electrolysis of AQUEOUS Na₂SO₄, what is the cell voltage? A) -2.06 V B) -3.94 V C) 0.40 V D) -2.16 V E) 1.78 V
E)
What is the oxidation state of bromine in BrO₃⁻? A) +7 B) +1 C) -1 D) +3 E) +5 F) 0
E)
A voltaic cell is constructed based on the following unbalanced reaction. When the cell contains 6.0 grams I₂, 10.0 grams solid Cr, 0.3 M Cr³⁺, and 0.2 M I⁻ at 298 K, what is the cell voltage? A. +1.28 V B. -1.45 V C. +1.10 V D. -1.12 V E. +1.33 V
E.
A voltaic cell is made from Pb and Co electrodes, immersed respectively in 1.0 M soultions of Pb(NO₃)₂ and Co(NO₃)₂. Which statement is true concerning the reaction? A. E⁰cell = 0.41 V B. ΔG°> 0 C. The voltage will increase as the mass of the Pb electrode is increased D. The reaction is non-spontaneous as written E. The cell voltage will decrease as more Co²⁺ is formed
E.
Calculate the value of ΔG (in KJ/mole) for this reaction at 25°C N₂(g)+3H₂(g)→2NH₃(g) K= 5.0 x 10⁸ A. 22 B. 50 C. -4.2 D. -25 E. -50
E.
Dr. Gordon has constructed a voltaic cell in his secret laboratory using a 5.0g Ni electrode in a solution with an initial concentration of 0.01 M Ni(NO₃)₂. Which statement is FALSE? A. The standard cell potential E° is 0 V. B. The cell potential Ecell will initially be 0.642 V C. The dilute solution acts as the anode and the concentrated solution acts as the cathode D. The concentration of Ni²⁺ ions in the dilute solution will increase as time passes E. Replacing the 5.0 g Ni electrode in the dilute solution with a 10.0 g Ni electrode will increase the cell potential
E.
Ksp is: A. Quantitative prediction about how much of a given ionic compound will dissolve in water B. The formation constant C. Equal to the product of the concentrations of the ions involved in the equilibrium, each raised to the power of it's coefficient D. Constant for a given solid at a given temperature E. A, B and D
E.
What is Ksp of Zn(OH)₂if the pH of a saturated solution in water is 8.66? A. 1.25 x 10⁻¹⁷ B. 1.05 x 10⁻²⁶ C. 4.57x 10⁻⁶ D. 9.55 x 10⁻¹⁷ E. 4.80 x 10⁻¹⁷
E.
When an aqueous solution which is 0.1 M in FeBr₃and 0.1 M in CuCl₂is electrolyzed, what is the initial product formed at the cathode? A. Cl₂(g) B. Br₂(g) C. Fe D. Cu E. Fe²⁺
E.
Which of the following are true for a voltaic cell at equilibrium? I. Ecell = 0 ii. ΔG = 0 iii. Q = K A. I only B. ii only C. iii only D. I and ii only E. I , ii, and iii
E.
Which of the following is the cathodic reaction in the electrolysis of aqueous NaI? A. Na⁺ + e⁻ → Na B. Na → Na⁺ + e⁻ C. 2 I⁻ → I₂ + 2 e⁻ D. I₂+ 2 e⁻ → 2 I⁻ E, 2 H₂O + 2 e⁻ → H₂+ 2 OH⁻
E.
Which of the following oxides would be most useful as an additive to remove SiO₂by an acid-base reaction in pyromettalurgy? A. V₂O₅ B. Mn₂O₇ C. CrO₃ D. Fe₂O₃ E. CaO
E.
Which of the following processes has a negative standard free energy change at 25°C? A. CO₂(g) + 2H₂O(l) → CH₄(g) + 2O₂(g) B. AgCl(s) → Ag⁺(aq) + Cl⁻(aq) C. 2KCl(s) → 2K(s) + Cl₂(g) D. 2H₂O(l) → 2H₂(g) + O₂(g) E. 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
E.
Which of the following reactions represents a dry cell battery? 1. 2 H₂(g) + O₂(g) → 4 OH⁻ 2. Li (s) + CoO₂ → LiCoO₂(s) 3. Pb(s) + PbO₂(s) + 4 H⁺ (aq) + 2 SO₄²⁻ (aq) → 2 PbSO₄(s) + 2 H₂O(l) 4. Zn(s) + 2MnO₂ (s) + 2 H₂O(l) → Zn(OH)₂(s) + 2MnO(OH)(s) 5. Zn(s) + 2NH₄⁺(aq) + 2MnO₂(s) → Zn²⁺(aq) + MnO₃(s) + 2 NH₃(aq) + H₂O(l) A. 1 B. 2 C. 3 D. 4 E. 5 F. None of the above
E.
Which of the following substances will not be more soluble in acidic solutions? A. Al(OH)₃ B. Ca₃(PO₄)₂ C. CaF₂ D. BaCO₃ E. PbI₂
E.
Which of the following substances, when added to a saturated solution of AgCO₃, will increase the solubility of AgCO₃in the solution? 1. Na₂CO₃ 2. AgNO₃ 3. HCl 4. NH₃ A. 1 and 2 B. 2 only C. 3 only D. 4 only E. 3 and 4
E.
Which one of the following elements uses hydromettalurgy as an important part in its processing? A. Pb B. Cr C. Fe D. Si E. Al
E.
Which one of the following salts is more soluble in acid than in neutral water? A. CaCl₂ B. Ca(ClO₄)₂ C. CaBr₂ D. CaI₂ E. CaF₂
E.
Which situation will help prevent the corrosion of iron? A. The presence of concentrated salt water B. The presence of acidic water C. Attatchment to a plate of solid copper D. Use of a platinum catalyst E. Coating with zinc metal
E.
T/F: Alkaline batteries and dry cell batteries are similar in appearance, and similar in the spontaneous chemical reactions responsible for producing a voltage
False
T/F: Concerning the lead storage battery, during winter, a charged battery is more likely to freeze than an uncharged one
False
T/F: Corrosion is NOT a spontaneous reaction
False
T/F: For a spontaneous process, increase in entropy of a system is always equal to the decrease in entropy of the surroundings
False
T/F: Fuel cells do not require a continuous supply of reactants to keep functioning
False
T/F: If a reaction is spontaneous, it cannot do work
False
T/F: Impurities do not reduce conductivity, therefore pure copper is not required in the electronics industry
False
T/F: In living systems, non-spontaneous reactions cannot be coupled with spontaneous reactions in order to drive a process forward
False
T/F: In non-standard conditions, the sign of ΔG° (not ΔG) determines spontaneity
False
T/F: Ksp is not constant for a given solid at a given temperature
False
T/F: Most metals do not come from minerals, they are mostly found as pure substances
False
T/F: The emf is an extensive property, it depends on the number of moles
False
T/F: The more negative the value of Ecell, the larger the driving force of the reaction
False
T/F: Under ordinary atmospheric conditions, water will spontaneously decompose to form hydrogen and oxygen gas
False
T/F: When ΔH is negative and ΔS is negative, ΔG is spontaneous at high temperatures but not at low temperatures
False
T/F: ΔS is spontaneous if ΔS system + ΔS surroundings < 0
False
A voltaic cell has the following reaction Al (s) + 3 Ag⁺(aq) → Al³⁺(aq) + Ag(s) 1. What will happen to the cell emf (Ecell) if water is added to the anode compartment? a) Ecell will increase b) Ecell will decrease c) This will have no effect
a)
For the following reaction, ΔG is positive: 2N₂(g) + 5O₂(g) + 2H₂O(l)↔ 4HNO₃(aq) Which statement about the equilibrium constant for the reaction is true? a. K < 1 b. K = 0 c. K = 1 d. K < 0 e. K > 1
a.
In the reaction: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s) Zn is called the .... a. reducing agent b. oxidizing agent
a.
Oxidation is... a. the loss of electrons b. the gain of electrons
a.
The following reaction takes place at room temperature: N₂(g) + 3H₂(g)→ 2 NH₃(g) For this reaction, which is true? a. ΔH°< 0, ΔS°< 0 b. ΔH°< 0, ΔS°> 0 c. ΔH°< 0, ΔS°> 0 d. ΔH°< 0, ΔS°> 0
a.
The metallurgical process of iron is a.... a. reduction process b. oxidation process
a.
Which reaction below occurs at the anode of a lead storage battery? x: Pb(s) + SO₄²⁻(aq) → PbSO₄²⁻ + 2e⁻ xx : PbO₂(s) + 4 H⁺(aq) + SO₄²⁻(aq) + 2e⁻ → PbSO₄(s) + 2H₂O(l) a. x b. xx
a.
Zn(s) + 2H⁺ → Zn²⁺ + H₂ What is the oxidation state of H²? a. 0 b. +1 c. -2 d. +2
a.
A voltaic cell has the following reaction Al (s) + 3 Ag⁺(aq) → Al³⁺(aq) + Ag(s) 1. What will happen to the cell emf (Ecell) if HCl is added to the AgNO₃solution? a) Ecell will increase b) Ecell will decrease c) This will have no effect
b)
In class it was noted that the combustion of hydrogen to produce water is spontaneous at room temperature. However, at high temperature, the decomposition reaction of water to hydrogen and oxygen (the reverse reaction) is spontaneous 2 H₂O(g)→2H₂(g) + O₂(g) ΔH°+ +484 kJ, ΔS°= +89 J/K What is the minimum temperature at which this decomposition reaction becomes spontaneous? a. 2110°C b. 5165°C c. 7210°C d. The correct answer is not given e. 100°C f. 560°C
b.
In the reaction: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s) Cu is called the... a. reducing agent b. oxidizing agent
b.
Reduction is... a. the loss of electrons b. the gain of electrons
b.
The metallurgical process of steelmaking is a.. a. reduction process b. oxidation process
b.
Which is the best oxidizing agent of the following? a. Cl⁻ b. Fe c. Fe³⁺ d. Fe²⁺ e. Cl₂
e.
Which of the following statements is false? a. A spontaneous reaction can be endothermic b. A spontaneous reaction can be very slow c. A catalyst can be used to speed up some spontaneous reaction d. For a system at equilibrium, delta g is zero e. A spontaneous reaction must have a negative enthalpy change
e.
Which of the following statements is incorrect? a. entropy always increases during evaporation and melting b. not all exothermic reactions are spontaneous c. Free energy is released for all exothermic reactions that have positive S values d. when the sign of the enthalpy and entropy are identical, the sign of the free energy depends on the temperature e. For a spontaneous process, increase in entropy of a system is always equal to the decrease in entropy of the surroundings
e.
