ACS General Chemistry 2 Practice Exam

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• Which expression correctly describes the nonstandard Gibbs free energy change?
• In the proposed mechanism for NO2 + F2 reaction, which step is rate-determining?
• For the reaction CH3COCH3(g) + 4 O2(g) → 3 CO2(g) + 3 H2O(l) at 25 °C with ΔH' = −184 kJ/mol and ΔS' = −236 J/mol·K, what is ΔG'?
• In a multi-step reaction, what is the rate-determining step?
• Which factor generally increases the solubility of sparingly soluble salts?
• Do catalysts change the position of chemical equilibrium?
• In a concentration cell, increasing the concentration difference between the two half-cells has what effect on the cell emf?
• What is the overall order of the reaction for rate = k [H2] [NO]^2?
• When comparing Q and Ksp for an unsaturated solution, which statement is correct?
• Standard reduction potentials can be used to judge spontaneity of a redox reaction by:
• In a strong acid–strong base titration, what is the pH at the equivalence point?
• An oxidation-reduction reaction in which 3 electrons are transferred has a Delta G° = 18.55 kJ/mol at 25 degrees C. What is the value of E°?
• An acetate buffer contains equal volumes of 0.35 M HC2H3O2 (pKa = 4.74) and 0.55 M NaC2H3O2. What is the pH of the buffer?
• Which condition indicates spontaneity at a given temperature according to ΔG?
• At a constant current of 1.26 A, how many grams of copper are deposited in 50.0 minutes?
• In a weak acid–strong base titration, the pH at the equivalence point is
• Which compound has the highest molar solubility in water given the following Ksp values: AgI 8.52 × 10^−17; BaCO3 2.58 × 10^−9; Fe(OH)3 2.79 × 10^−39; ZnS 3.00 × 10^−23?
• In constant-pressure calorimetry, what is the sign convention for qrxn and qcal?
• What current is required to plate 4.00 g copper in 60.0 minutes?
• In Henry's law S = k_H p, with S in mol/L and p in atm, what are the units of k_H?
• Which statement is correct for the reaction below under standard conditions? 2Cl2 (g) + 2NO (g) → N2 (g) + 2Cl2O (g); ΔH° = -22.0 kJ/mol
• If Q is the reaction quotient and K is the equilibrium constant, which statement is true when Q < K?
• In the reaction X2 (g) + 2Y(g) ⇌ 2Z (g). 12.00 moles of Z are placed in an evacuated 2.00-liter flask. After equilibrium, the flask contains 6.00 moles of Y. What is the equilibrium constant, K, for the reaction?
• State Raoult's law for vapor pressures in a mixture of two volatile solvents.
• Solubility product constant Ksp for Mg(OH)2 is sought when its molar solubility in water is 1.6 × 10^−4 M. Which value is correct for Ksp?
• Which statement about Le Châtelier's principle is true?
• What is a concentration cell?
• In a binary alloy AB at a certain temperature, two solid phases α and β have compositions Xα = 0.25 and Xβ = 0.75 (mole fraction of B). If the overall alloy composition is X0 = 0.50, what is the fraction of α phase present according to the lever rule?
• If a reaction has ΔH < 0 and ΔS > 0, the process is spontaneous:
• Colligative properties depend on which characteristic of solute particles?
• For rate = k [H2] [NO]^2, if [H2] is doubled, the rate increases by what factor?
• An equilibrium mixture of I2 (g), Cl2 (g), and ICl (g) at 298 K has partial pressures of 0.0100 atm, 0.0100 atm, and 0.0900 atm, respectively. What is ΔG° at 298 K for the reaction I2 (g) + Cl2 (g) ⇌ 2 ICl (g)?
• What is the van't Hoff equation for osmotic pressure in dilute solutions?
• Which change will alter the value of Ksp for the salt AgN3?
• Which anion is the most basic?
• A solution contains 0.002 M Pb^2+ and 0.002 M Ag^+. When NaCl(s) is added to raise Cl− to 0.01 M, which substance precipitates first or at all?
• Henry's law connects partial pressure of a gas with what property of the dissolved gas in the liquid?
• In a sealed container at 25°C, the gas-phase equilibrium 2BrCl(g) ⇌ Br2(g) + Cl2(g) has Kp = 0.130. If initially BrCl(g) = 0.400 atm, Br2(g) = 0.800 atm, and Cl2(g) = 0.800 atm, what is the BrCl(g) partial pressure at equilibrium?
• In calorimetry, what does C_cal represent?
• Which action increases the concentration of gas dissolved in a liquid?
• Calculate the standard Gibbs free energy change at 298 K for the reaction FeO4 (s) + 4 CO (g) ⇌ 3 Fe (s) + 4 CO2 (g).
• How many grams of copper are deposited in 60.0 minutes at 1.26 A?
• State Raoult's law for an ideal solution.
• What is the correct statement about the autoionization of water at 25°C?
• At the eutectic point of a ternary system, which of the following is true?
• Which 0.1 molal aqueous solution will have the lowest freezing point?
• Which statement about solubility in a solution with a common ion is true?
• If the standard cell potential for a reaction is positive, the reaction is:
• What is the Arrhenius equation and how does temperature affect k?
• What is Henry's law and when is it applicable?
• Lowering the pH (making the solution more acidic) has what effect on the solubility of metal hydroxides such as Fe(OH)3?
• In electrolysis, how is the amount of substance produced at an electrode determined?
• For the reaction 2SO2 + O2 ⇌ 2SO3, when the pressure is increased, the forward rate increases and the yield of SO3 increases because the forward reaction reduces the total number of gas molecules. Which statement best explains this observation?
• Define buffer capacity and buffer range.
• An acetate buffer is prepared with 0.100 M HOAc and 0.100 M NaOAc. If pKa(HOAc) = 4.74, what is the pH?
• Which statement correctly describes buffer capacity?
• Phosgene decomposes into carbon monoxide and elemental chlorine. If the initial concentration of COCl2 (g) is 0.50 M, what is the equilibrium concentration of CO (g)? Ke = 6.6 x 10^-8
• Which expression represents the Nernst equation at 25°C for a cell reaction that transfers n electrons?
• Which statement about hydrolysis of salts is correct?
• Which term describes the cell potential measured when no current flows (open-circuit condition)?
• What is Kb of F-? Ka of HF is 6.8 × 10^-4
• Write the Ksp expression for Ca(OH)2(s) ⇌ Ca2+(aq) + 2 OH−(aq).
• The equation ΔG° = −RT ln K relates standard free energy change to what?
• If reaction quotient Q equals 1, what is ΔG relative to ΔG°?
• Which factors determine boiling point elevation and freezing point depression for a given solute?
• What is the atomic number of iodine?
• For a spontaneous galvanic cell, what is the sign of ΔG?
• What are the units of molality?
• Which statement best describes how the observed rate law is determined in a mechanism?
• How do you compute ΔHrxn° from standard enthalpies of formation?
• How does a catalyst affect a reaction's activation energy and rate?
• How does increasing temperature affect the equilibrium constant K for endothermic and exothermic reactions?
• Which of the following are colligative properties?
• Consider the reaction Cu2+ (aq) + Fe (s) → Cu (s) + Fe2+ (aq) E° = 0.78 V. What is the value of E when [Cu2+] = 0.040 M and [Fe2+] = 0.40 M?
• What does the van't Hoff factor i account for in colligative properties?
• Which acid is the weakest in aqueous solution?
• Which equation correctly relates standard Gibbs free energy change to the equilibrium constant at a given temperature?
• If a nonvolatile solute is added to a solvent, what happens to the freezing point?
• How can you determine reaction order from rate law data?
• Precipitation will occur when the ionic product exceeds Ksp, causing the system to adjust until:
• Which statement about the Arrhenius temperature dependence of the rate constant k is correct?
• For a second-order reaction with a single reactant, the integrated rate law is which form?
• If the standard cell potential E° is positive, what is the sign of ΔG°?
• A mixture contains 100 g of potassium dichromate, K2Cr2O7, and 200 g of water. The mixture is saturated at 60 °C and then cooled to 20 °C, allowing crystals to form. What mass of K2Cr2O7 crystallizes from the solution during cooling?
• Distinguish between solubility and dissolution rate; how does temperature typically affect each for a salt?
• How does complex formation with ligands affect solubility of a sparingly soluble salt?
• For a reaction with Q > K, which direction will the reaction proceed?
• State Henderson-Hasselbalch equation and its common-use scenario.
• State Hess's law in your own words.
• State the Nernst equation for a half-cell reaction at 25°C.
• Write the Ksp expression for AB(s) ⇌ A+(aq) + B−(aq).
• Which statement correctly differentiates solubility from dissolution rate?
• The half-life for first-order radioactive decay of 32P is 14.3 days. How many days would be required for the activity to decrease to 20.0% of its initial value?
• Which expression gives the half-life of a first-order reaction?
• What is the physical meaning of the Arrhenius pre-exponential factor A in k = A e^(−Ea/RT)?
• If the plating current is doubled from 1.26 A to 2.52 A while depositing 2.08 g of copper, approximately how many minutes are required?
• What are ΔHfus and ΔHvap?
• Which statement best describes how to determine entropy-driven versus enthalpy-driven using ΔG = ΔH − TΔS?
• In rate law rate = k[A]^m[B]^n, the exponents m and n represent what?
• For a reaction where K > 1 at all temperatures, which statement(s) must be true?
• Which statement about Kw is true?
• For an endothermic dissolution process, what is the typical effect of increasing temperature on the solubility and Ksp?
• Beta decay of an atom with atomic number 53 and mass number 131 yields a residual atom with which Z and A?
• Which relation connects Gibbs free energy change and cell potential for a galvanic cell?
• What is the standard Gibbs free energy change for the formation of one mole of ammonia from its elements under standard conditions?
• If ΔG = ΔH − TΔS, which statement is true when ΔG < 0 at a given temperature?
• What is the coefficient for the nitrate ion (NO2−) when the redox reaction is balanced in basic solution? MnO4− (aq) + NO2− (aq) → MnO2 (s) + NO3− (aq)
• For a first-order reaction, the half-life t1/2 is related to k by which expression?
• In a 200 g sample of solution that is 89% by mass ethanol, what is the mole fraction of ethanol?
• In a buffer solution near its pKa, the pH changes slowly with added acid or base, and pH is approximately equal to pKa when:
• If a saturated solution of MgCO3 is placed in contact with a large supply of Mg2+ ions, what happens to its solubility?
• What is the Gibbs phase rule for a system with C components and P phases at fixed temperature and pressure? F = ?
• What is the effect of adding a common ion on the solubility of a sparingly soluble salt?
• During the reduction of copper(II) oxide by carbon monoxide, CuO(s) + CO(g) ⇌ Cu(s) + CO2(g), which change will drive the equilibrium toward more Cu(s) production?
• What is the general effect of increasing temperature on the solubility of most solid solutes in water?
• A freezing point depression problem: A solute lowers the freezing point by 6.36 °C in 1.00 kg of water. Using Kf for water = 1.86 °C/m and assuming the solute dissociates into two particles, which compound is the unknown solute? (CsCl, KCl, LiF, NaCl)
• Which statement about spontaneity and ΔG = ΔH − TΔS is true?
• In a reaction mechanism, what is the steady-state approximation?
• When NH4NO3 dissolves in water, the temperature of the solution decreases. What describes the enthalpy change, entropy change, and which change drives the process?
• For the reaction: NO2 (g) + F2 (g) ⇌ 2 NO2F (g), a proposed mechanism has the slow step NO2 + F2 ⇌ NO2F + F and a fast step NO2 + F ⇌ NO2F. What is the rate law for this mechanism?
• In a concentration cell with identical electrodes, what is the emf when the ion concentrations are equal on both sides?
• What is the pH of a 0.820 M aqueous ammonia solution? Ka? Kb (NH3) = 1.8 × 10^-5
• Given the standard reduction potentials at 25 degrees C, what is the standard cell potential of a Ni (s) | Ni2+ (aq) || Ag+ (aq) | Ag (s) galvanic cell?
• If the equilibrium constant K is much larger than 1, what can be said about ΔG° at that temperature?
• In beta decay, what happens to the mass number A?
• The standard Gibbs free energy change ΔG° is related to standard cell potential E° by which equation?
• What effect does a catalyst have on the activation energy and reaction rate?
• What is Kw and its value at 25°C?
• For a system in which Q equals K, what is true?
• Which expression correctly approximates the pH of a dilute solution of a monoprotic weak acid with concentration C and Ka?
• For the concentration cell Fe(s) | Fe3+ (0.100 M) || Fe3+ (1.00 M) | Fe(s) at 25 C, what is Ecell in millivolts?
• For the equilibrium COCl2 (g) ⇌ CO (g) + Cl2 (g), what is the expression for Ke in terms of concentrations?
• Which half-life expression is correct for a zero-order reaction?
• Describe the general steps of an ICE table for the reaction aA + bB ⇌ cC + dD to find equilibrium concentrations.
• Which statement correctly describes Raoult's law and Henry's law?
• Which constant equals approximately 96485 C/mol and relates electric charge to moles of electrons?
• What is the mole fraction of water in 200 g of a solution that is 89% by mass ethanol (C2H5OH)?
• How does formation of a complex ion affect the solubility of a sparingly soluble salt?
• Which statement best describes osmotic pressure?
• Which statement about the cathode in a galvanic cell is true?
• How do you compute the standard cell potential E°cell from two half-reactions?
• What is the integrated rate law for a first-order reaction?
• Write the solubility product expression for PbSO4(s) ⇌ Pb2+(aq) + SO4^2−(aq) and interpret Ksp.
• What is the difference between the reaction quotient Q and the equilibrium constant K?
• Which expression represents Raoult's law for a solution with a volatile solvent and a nonvolatile solute?
• Why does Fe(OH)3 solubility increase under acidic conditions?
• How does increasing total pressure affect the solubility of gases in liquids?
• For a zero-order reaction, the integrated rate law is which expression?
• What is the relationship between the equilibrium constant K and the reaction quotient Q?
• Which entropy value is incorrectly reported at 298 K among the following species: Ca (s) S' = 202; Br2 (l) S' = 152; CO2 (g) S' = 214; AlCl3 (s) S' = 109?
• Why doesn't a catalyst alter the final equilibrium composition?
• A solution consists of 20.5 g of NaCl dissolved in 100 g of solution. What is the molality of NaCl in this solution?
• Which law relates vapor pressure of a liquid mixture to the mole fraction of solvent in an ideal solution?
• In acidic solution, the half-reactions during electrolysis of water are:
• In Ni(CO)4 (g) ⇌ Ni(s) + 4 CO (g), why is the activity of Ni(s) not included in the equilibrium expression?
• If the dissolution of CaF2 has Ksp = 4.0 × 10^−11 and the equilibrium [Ca^2+] = 1.0 × 10^−2 M, what is [F−] at equilibrium?
• Using Henderson-Hasselbalch for a weak acid: pH = pKa + log([A−]/[HA]). If a strong base is added to a weak acid buffer, what happens to the ratio and pH?
• If the equilibrium constant K for a reaction is much greater than 1, which statement is true about the equilibrium mixture?
• How is the standard cell potential E°cell determined from half-cell potentials?
• Which rate law is correct for the reaction 2H2 (g) + 2NO (g) → N2 (g) + 2H2O (g)?
• What volume (in mL) of 0.150 M NaOH (aq) is required to neutralize 25.0 mL of 0.100 M H2SO4 (aq)?
• According to the Arrhenius equation, what is the effect of increasing temperature on the rate constant k when Ea > 0?
• The activation energy for a particular reaction is 83.1 kJ/mol. By what factor will the rate constant increase when the temperature is increased from 550.0 degrees C to 60.0 degrees C?
• For an ideal gas expanding reversibly from volume V1 to V2 at constant temperature, which expression correctly gives ΔS?
• What is the Clapeyron equation and what does it relate?
• In the electrolysis of molten sodium iodide, which species is oxidized at the anode?
• What defines a concentration cell and its emf?
• If ΔH < 0 and ΔS > 0, what can be said about spontaneity across all temperatures?
• In hard water containing Ca^2+ at 2.0 × 10^−2 M, what is the maximum fluoride concentration allowed before CaF2(s) begins to precipitate, given Ksp = 4.0 × 10^−11?
• For the reaction A + B → C + D, rate law is first order in [A] and second order in [B]. If [A] is halved and [B] is doubled, the rate of the reaction will
• Le Châtelier's principle predicts that increasing pressure will shift equilibria toward the side with fewer moles of gas. This statement applies to...
• Gas solubility generally increases when temperature decreases. Which option correctly identifies this statement?
• The final yield of a reversible reaction is determined by:
• At the equivalence point of a weak acid-strong base titration, the pH is:
• Using pKa ≈ 4.76 for acetic acid, estimate the pH of a 0.10 M acetate buffer with equal 0.10 M acetic acid and acetate.
• What happens to a system at equilibrium if more reactant is added?
• At equilibrium, what is true about the rates of the forward and reverse reactions?
• What is the overall balanced equation for the electrolysis of water in acidic solution?
• In a concentration cell, what is the emf when both solutions have identical concentrations?
• For the equilibrium A ⇌ B with K = [B]/[A], what happens to [A] and [B] if more A is added?
• What is the value of ΔG° when K = 1?
• At 1.26 A, how long (in minutes) would it take to deposit 1.00 g of copper?
• Which statement correctly describes a galvanic cell with a positive standard cell potential E°cell?
• What is the value of the equilibrium constant K for the overall reaction Cr(OH)3(s) + OH−(aq) ⇌ [Cr(OH)4]−(aq) given Ksp = 1.6 × 10^−30 and Kf = 8.0 × 10^29?
• What is the value of ΔG for a system at equilibrium?
• In constant-pressure calorimetry, for an endothermic reaction, which statement about qrxn and qcal is true?
• What is the expression for osmotic pressure in dilute solutions?
• In a ternary eutectic system, what occurs at the eutectic point?
• In copper plating from a Cu2+-containing solution, which half-reaction occurs at the cathode?
• What is the mass of ethanol in the 200 g sample described above (89% by mass ethanol)?
• What is the basic operating principle of a galvanic (electrochemical) cell?
• What is the equilibrium expression for Ni(CO)4 (g) ⇌ Ni (s) + 4 CO (g)?
• Describe the common method to balance redox reactions in acidic solution.
• In the equation m = (I t)/(n F) × M, what does F represent?
• Which change is most likely to be accompanied by an increase in entropy?
• If the initial-rate data show that doubling [A] while keeping [B] constant doubles the rate, what is the order with respect to A?
• Which describes the conjugate acid of NH3?
• Consider the equilibrium 2SO2 (g) + O2 (g) ⇌ 2SO3 (g). The forward reaction rate is observed to increase when the pressure is raised. What is the expected effect on the forward rate and the equilibrium yield of SO3?
• Which information is used to determine the order of a reaction with respect to a given species from rate data?
• Which statement regarding chemical reactions is true according to collision theory?
• In the gas-phase equilibrium 2BrCl(g) ⇌ Br2(g) + Cl2(g), what happens if the container volume is decreased (pressure increased) at constant temperature?
• What is the pH of a 0.10 M strong acid solution like HCl?
• What happens at the critical point on a phase diagram?
• The mass of copper deposited by electrolysis is proportional to which of the following?
• Which expression represents the first law of thermodynamics in terms of ΔU, q, and w?
• In a phase diagram, what does the line between two phases represent?
• At constant volume, the change in internal energy is equal to which of the following?
• If Ke for the reaction 2SO3 (g) ⇌ 2SO2 (g) + O2 (g) is 2.3 x 10^-7, what is the equilibrium constant for the reverse reaction?
• Which expression correctly relates Gibbs free energy change to enthalpy and entropy at constant pressure and temperature?
• For the dissolution of BaSO4(s) ⇌ Ba^2+(aq) + SO4^2−(aq), if the solubility is s, which expression gives Ksp?
• If a binary alloy (C = 2) exists with two phases at fixed T and P, how many degrees of freedom F are allowed?
• One Faraday equals how many coulombs?
• Which statement is true about the relationship between Q and K at equilibrium?
• Buffer capacity is influenced by concentration and pH relative to pKa. Which statement is true?
• At constant pressure, heat flow equals which thermodynamic quantity?
• Which substance dissolves in water to produce an acidic solution?
• In a pressure–volume system, which type of work is zero when the volume is held constant?
• Le Chatelier's principle: how does increasing temperature affect an exothermic reaction's equilibrium?
• In beta decay, what happens to the atomic number Z?
• What does buffer capacity depend on?
• In the dissolution of Ca(OH)2, the hydroxide ion appears to the power of what in the Ksp expression?
• If a sparingly soluble salt is added to solution with a common ion, what happens to its solubility?
• The half-life for the first-order conversion of cyclobutene to ethylene is 22.7 s at a given temperature. How many seconds are needed for the partial pressure of cyclobutene to decrease from 100 mmHg to 10 mmHg?
• Explain the common-ion effect and its impact on solubility.
• If a gas-phase equilibrium A ⇌ B has Δn_gas = 0, what is the relationship between Kp and Kc?
• If a solute does not dissociate in solution, its van't Hoff factor i is approximately
• A nonvolatile solute is added to a volatile solvent. According to Raoult's law, the solvent's vapor pressure:
• What thermodynamic criterion determines spontaneity of a process at constant temperature and pressure?
• What does the phase diagram triple point represent?
• Which statement best describes colligative properties?
• During electrolysis of molten sodium iodide, what is the half-reaction occurring at the anode?
• For dissolution endothermic with positive ΔS, how does ΔG° change with increasing temperature?
• Henry's law states that the concentration of a dissolved gas is proportional to its partial pressure, described by C = kH P. Under constant temperature, doubling P will:
• What is the pH at the equivalence point for a strong acid-strong base titration?
• For a reaction A ⇌ B, if the reaction quotient Q is less than the equilibrium constant K, in which direction will the reaction proceed?
• What happens to the position of equilibrium for an exothermic reaction when the temperature is increased?
• What is the Ksp expression for MgCO3 in water?