Chem 102 final
When 1.30 mol of CO2 and 1.30 mol of H2 are placed in a 3.00-L container at 395 ∘C, the following reaction occurs: CO2(g)+H2(g)⇌CO(g)+H2O(g) If Kc = 0.802, what is the concentration of CO in the equilibrium mixture?
0.205 M
The vapor pressure of ethanol (C2H5OH) at 19 ∘C is 40.0 torr. A 0.700 g sample of ethanol is placed in a 2.60 L container at 19 ∘C. If the container is closed and the ethanol is allowed to reach equilibrium with its vapor, how many grams of liquid ethanol remain?
0.44 g
Consider the following isomerization reactions of some simple sugars and values for their standard Gibbs free energy ΔG∘: reaction A:reaction B:glucose-1-phosphatefructose-6-phosphate⟶⟶glucose-6-phosphate,glucose-6-phosphate, ΔG∘=−7.28 kJ/mol ΔG∘=−1.67 kJ/mol 1. Calculate ΔG∘ for the isomerization of glucose-1-phosphate to fructose-6-phosphate. 2. Calculate the equilibrium constant K for the isomerization of glucose-1-phosphate to fructose-6-phosphate at 298 K.
1. -5.61 kJ/mol 2. 9.6
Using the values given for ΔH∘ and ΔS∘, calculate ΔG∘ for each of the following reactions at 298 K. 1. 2PbS(s)+3O2(g)→2PbO(s)+2SO2(g), ΔH∘=−844 kJ, ΔS∘=−165 J/K 2. 2POCl3(g)→2PCl3(g)+O2(g), ΔH∘=572 kJ, ΔS∘=179 J/K 3. Select the reaction(s) that are spontaneous under standard conditions at 298 K. a. 2POCl3(g)→2PCl3(g)+O2(g) b. 2PbS(s)+3O2(g)→2PbO(s)+2SO2(g) 4. At what temperature (if any) would the decomposition of POCl3 become spontaneous?
1. -795 kJ 2. 519 kJ 3. b 4. 3.20x103 K
At 700 K the equilibrium constant for the reaction CCl4(g)←−→C(s)+2Cl2(g) is Kp=0.76. A flask is charged with 2.10 atm of CCl4, which then reaches equilibrium at 700 K. 1. What fraction of the CCl4 is converted into C and Cl2? 2. What is the partial pressure of CCl4 at equilibrium? 3. What is the partial pressure of Cl2 at equilibrium?
1. 0.26 2. 1.6 atm 3. 1.1 atm
Gaseous iodine pentafluoride, IF5, can be prepared by the reaction of solid iodine and gaseous fluorine: I2(s)+5F2(g)→2IF5(g) A 4.60 −L flask containing 9.20 g I2 is charged with 9.20 g F2, and the reaction proceeds until one of the reagents is completely consumed. After the reaction is complete, the temperature in the flask is 125 ∘C. 1. What is the partial pressure of IF5 in the flask? 2. What is the mole fraction of IF5 in the flask? 3. What is the total mass of reactants and products in the flask?
1. 0.515 atm 2. 0.544 atm 3. 18.4 g
A flask is charged with 1.650 atm of N2O4(g) and 1.00 atm of NO2(g) at 25 ∘C , and the following equilibrium is achieved: N2O4(g)⇌2NO2(g) After equilibrium is reached, the partial pressure of NO2 is 0.513 atm. 1. What is the partial pressure of N2O4 at equilibrium? 2. Calculate the value of Kp for the reaction. 3. Calculate the value of Kc for the reaction.
1. 1.89 atm 2. 0.139 3. 5.86x10⁻³
Consider the titration of 30.0 mL of 0.050 M NH3 with 0.025 M HCl. Calculate the pH after the following volumes of titrant have been added. 1. 0 mL 2. 20.0 mL 3. 59.0 mL 4. 60.0 mL
1. 10.98 2. 9.56 3. 7.48 4. 5.52
Carbon disulfide (CS2) boils at 46.30 ∘C and has a density of 1.261 g/mL. 1. When 0.240 mol of a nondissociating solute is dissolved in 410.0 mL of CS2, the solution boils at 47.39 ∘C. What is the molal boiling-point-elevation constant for CS2? 2. When 5.39 g of a nondissociating unknown is dissolved in 50.0 mL of CS2, the solution boils at 47.08 ∘C. What is the molecular weight of the unknown?
1. 2.34 °C/m 2. 260 g/mol
The temperature for each solution is carried out at approximately 297 K where Kw=1.00×10−14. 1. 0.35 g of hydrogen chloride (HCl) is dissolved in water to make 3.0 L of solution. What is the pH of the resulting hydrochloric acid solution? 2. 0.10 g of sodium hydroxide (NaOH) pellets are dissolved in water to make 2.5 L of solution. What is the pH of this solution? 3. What is the pOH of the solution in Part 2?
1. 2.49 2. 11.00 3. 3.00
Assume that 25.0 mL of a 0.10 M solution of a weak base B that accepts one proton is titrated with a 0.10 M solution of the monoprotic strong acid HA. 1. How many moles of HA have been added at the equivalence point? 2. What is the predominant form of B at the equivalence point? a. BA−(aq) b. BA(aq) c. BOH−(aq) d. BH+(aq) e. B(aq) 3. Is the pH 7, less than 7, or more than 7 at the equivalence point? a. pH is 7. b. pH is less than 7. c. pH is more than 7.
1. 2.5x10⁻³ mol 2. d 3. b
The metabolic oxidation of glucose, C6H12O6, in our bodies produces CO2, which is expelled from our lungs as a gas: C6H12O6(aq)+6O2(g)→6CO2(g)+6H2O(l) 1. Calculate the volume of dry CO2 produced at body temperature (37 ∘C) and 0.980 atm when 24.0 g of glucose is consumed in this reaction. 2. Calculate the volume of oxygen you would need, at 1.00 atm and 298 K, to completely oxidize 54 g of glucose.
1. 20.8 L 2. 44.0 L
The Henry's law constant for helium gas in water at 30 ∘C is 3.7×10−4M/atm; the constant for N2 at 30 ∘C is 6.0×10−4M/atm. 1. If helium gas is present at 1.3 atm pressure, calculate the solubility of this gas. 2. If N2 is present at 1.3 atm pressure, calculate the solubility of this gas.
1. 4.8x10⁻⁴ M 2. 7.8x10⁻⁴ M
A buffer contains 0.16 mol of propionic acid (C2H5COOH) and 0.26 mol of sodium propionate (C2H5COONa) in 1.20 L. 1. What is the pH of this buffer? 2. What is the pH of the buffer after the addition of 0.02 mol of NaOH? 3. What is the pH of the buffer after the addition of 0.02 mol of HI?
1. 5.10 2. 5.19 3. 5.01
A scuba diver's tank contains 0.29 kg of O2 compressed into a volume of 2.3 L. 1. Calculate the gas pressure inside the tank at 7 ∘C. 2. What volume would this oxygen occupy at 27 ∘C and 0.92 atm ?
1. 91 atm 2. 240 L
The reaction PCl3(g)+Cl2(g) ⇌ PCl5(g) has Kp=0.0870 at 300 ∘C. A flask is charged with 0.50atmPCl3, 0.50atmCl2, and 0.20atmPCl5 at this temperature. 1. Use the reaction quotient to determine the direction the reaction must proceed in order to reach equilibrium. a. the reaction proceeds to the left b. the reaction proceeds to the right 2. Calculate the equilibrium partial pressures of PCl3. 3. Calculate the equilibrium partial pressures of Cl2. 4. Calculate the equilibrium partial pressures of PCl5. 5. What effect will increasing the volume of the system have on the mole fraction of Cl2 in the equilibrium mixture? a. the mole fraction of Cl2 decreases b. the mole fraction of Cl2 increases 6. The reaction is exothermic. What effect will increasing the temperature of the system have on the mole fraction of Cl2 in the equilibrium mixture? a. the mole fraction of Cl2 decreases b. the mole fraction of Cl2 increases
1. a 2. 0.66 atm 3. 0.66 atm 4. 3.8x10⁻² atm 5. b 6. b
PCl5(g) decomposes into PCl3(g) and Cl2(g). A pure sample of PCl5(g) is placed in a rigid, evacuated 1.00 L container; the initial pressure of PCl5 is 1.00 atm. At constant temperature, the PCl5 reaches equilibrium with its decomposition products as follows to have a Ptotal of 1.40 atm. PCl5(g) ↔ PCl3(g) + Cl2(g) 1. As the reaction proceeds toward equilibrium, the rate of the forward reaction: a. Increases until it becomes the same as the reverse reaction rate at equilibrium b. Stays constant before and after equilibrium is achieved. c. Decreases to a constant nonzero rate at equilibrium. d. Decreases to become zero at equilibrium. 2. If the reaction were to go to completion, the total pressure in the container would be 3. Which of the following statements about Kp is correct? a. Kp > 1 b. Kp < 1 c. Kp = 1 d. Kp cannot be determined without more information.
1. c 2. 2.0 atm 3. b
As the intermolecular attractive forces between molecules increase in magnitude, do you expect each of the following to increase or decrease in magnitude? 1. vapor pressure 2. heat of vaporization 3. boiling point 4. freezing point 5. viscosity 6. surface tension 7. critical temperature
1. decrease 2. increase 3. increase 4. increase 5. increase 6. increase 7. increase
Propanoic acid reacts with water according to this equation: CH3CH2COOH(aq) + H2O ⇌ CH3CH2CO2-(aq) + H3O+(aq) At 25oC, the pH of a 50.0 mL sample of 0.20 M CH3CH2COOH is 2.79. What is the Ka for propanoic acid?
1.32x10⁻⁵
A solution of sodium acetate (NaCH3COO) has a pH of 9.46. The acid-dissociation constant for acetic acid is 1.8×10−5. What is the molarity of the solution?
1.5 M
Saccharin, a sugar substitute, is a weak acid with pKa=2.32 at 25 ∘C. It ionizes in aqueous solution as follows: HNC7H4SO3(aq)←−→H+(aq)+NC7H4SO−3(aq) What is the pH of a 0.14 M solution of this substance?
1.63
How many grams of water can be cooled from 42 ∘C to 16 ∘C by the evaporation of 56 g of water? (The heat of vaporization of water in this temperature range is 2.4 kJ/g. The specific heat of water is 4.18 J/g⋅K.) Express your answer using two significant figures.
1200 g
Calculate the molar mass of a vapor that has a density of 7.130 g/L at 13 ∘C and 743 torr .
171 g/mol
For the elementary process N2O5(g)→NO2(g)+NO3(g) the activation energy (Ea) and overall ΔE are 154 kJ/mol, and 136 kJ/mol, respectively. What is the activation energy for the reverse reaction?
18 kJ/mol
At an underwater depth of 245 ft, the pressure is 8.37 atm. What should the mole percent of oxygen be in the diving gas for the partial pressure of oxygen in the mixture to be 0.21 atm, the same as in air at 1 atm?
2.5 %
Nitrogen and hydrogen gases react to form ammonia gas via the following reaction: N2(g)+3H2(g)→2NH3(g) At a certain temperature and pressure, 1.4 L of N2 reacts with 4.2 L of H2. If all the N2 and H2 are consumed, what volume of NH3, at the same temperature and pressure, will be produced?
2.8 L
H2(g)+I2(g)⇌2HI(g) For the above reaction, Kc=55.3 at 700 K. In a 2.00-L flask containing an equilibrium mixture of the three gases, there are 0.059 g of H2 and 4.39 g of I2. What is the mass of HI in the flask?
21 g
What is the H+ concentration for an aqueous solution with pOH = 2.54 at 25 ∘C?
3.5x10-12 M
A dilute aqueous solution of an organic compound soluble in water is formed by dissolving 2.35 g of the compound in water to form 0.250 L solution. The resulting solution has an osmotic pressure of 0.605 atm at 25 ∘C. Assuming that the organic compound is a nonelectrolyte, what is its molar mass?
380 g/mol
The reaction 2NO(g)+O2(g)→2NO2(g) is second order in NO and first order in O2. When [NO]= 4.7×10−2 M and [O2]= 4.3×10−2 M , the observed rate of disappearance of NO is 8.7×10−5 M/s . What is the rate of disappearance of O2 at this moment?
4.4x10⁻⁵ M/s
Suppose a pinhole is in the cork that stoppers the flask in which the equilibrium mixture is found, where PPCl3 = PCl2. It requires 35 hours for the chlorine gas to effuse from the system. How long (hrs) does it take for the phosphorus trichloride to effuse? MM(Cl₂) = 71 g/mol MM(PCl₂) = 137 g/mol
49 hr
A buffer is prepared by adding 18.0 g of sodium acetate (CH3COONa) to 520 mL of a 0.140 M acetic acid (CH3COOH) solution. Determine the pH of the buffer.
5.22
Calculate the density of sulfur hexafluoride gas at 707 torr and 22 ∘C.
5.61 g/L
At a certain temperature, the pH of a neutral solution is 7.58. What is the value of Kw at that temperature?
6.9x10-16
The first-order rate constant for decomposition of a typical insecticide in the environment is 3.43 x 10-2 days-1. How long does it take for the concentration of insecticide to drop to 1/10 of its initial value?
67 days
What is the pH at the equivalence point when 0.10 M HNO3 is used to titrate a volume of solution containing 0.30 g of KOH? Express your answer as an integer.
7
50.0 mL HA requires 40.0 mL 0.100 M NaOH to achieve equivalence point. What is the pH at the equivalence point? Ka = 1.32x10⁻⁵
8.76
A 16.0 −L tank is filled with helium gas at a pressure of 105 atm. How many balloons (each 2.00 L) can be inflated to a pressure of 1.00 atm, assuming that the temperature remains constant and that the tank cannot be emptied below 1.00 atm?
832
Which acid has the larger acid-dissociation constant, HIO2 or HBrO3?
HBrO₃
Select the substance that has the higher boiling point. HOOH HSSH
HOOH
Methanol (CH3OH) is produced commercially by the catalyzed reaction of carbon monoxide and hydrogen: CO(g)+2H2(g)←→CH3OH(g). An equilibrium mixture in a 2.50 −L vessel is found to contain 2.46×10−2 mol CH3OH, 0.160 mol CO, and 0.303 mol H2 at 500 K.
Kc = 10.5
A 25.0 mL sample of 0.150 M acetic acid is titrated with a 0.150 M NaOH solution. What is the pH at the equivalence point? The Ka of acetic acid is 1.8 ⋅ 10-5. a. 8.81 b. 4.74 c. 7.00 d.11.74 e. 9.26
a
A solution with a concentration higher than the solubility is ________. a. supersaturated b. saturated c. not possible d. unsaturated e. supercritical
a
Calculate the standard entropy change for the reaction: 2CH3OH(g)+3O2(g)→2CO2(g)+4H2O(g) Where: 1. S0[H2O(g)]=189 J/k mol 2. S0[CO2(g)]=214 J/k mol 3. S0[O2(g)]=205 J/k mol 4. S0[CH3OH(g)]=240 J/k mol a. +89 J/K b. -2279 J/K c. +2279 J/K d. -89 J/K
a
For the reaction 2 C4H10 (g) + 13 O2 (g) → 8 CO2 (g) + 10 H2O (g) Δ H° is -125 kJ/mol and Δ S° is +253 J/K ⋅ mol. This reaction is ________. a. spontaneous at all temperatures b. spontaneous only at high temperature c. nonspontaneous at all temperatures d. spontaneous only at low temperature e. unable to determine without more information
a
Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction: 2NO2→2NO+O2 In a particular experiment at 300 ∘C, [NO2] drops from 0.0151 to 0.00863 M in 156 s . The rate of disappearance of NO2 for this period is ________ M/s. a. 4.15×10−5 b. 2.07×10−5 c. 2.41×104 d. −1.52×10−4 e. 8.29×10−5
a
The reaction 2NO2 → 2NO + O2 follows second-order kinetics. At 300 °C, [NO2] drops from 0.0100 M to 0.00650 M in 100.0 s. The rate constant for the reaction is ________ M-1s-1. a. 0.54 b. 0.81 c. 1.2 d. 0.65 e. 0.096
a
The reaction A→B is first order reaction in [A]. Consider the following data. Time (s) [A] (M) 0.0 2.7 10.0 0.68 20.0 0.17 The half-life of this reaction is ________ s. a. 5.0 b. 0.14 c. 0.97 d. 7.1 e. 3.0
a
Which aqueous solution will have the lowest freezing point? a. 0.15 m NaCl b. 0.050 m CaCl2 c. 0.10 m HCl d. 0.050 m CH3COOH e. 0.20 m C12H22O11
a
Which of the following changes always leads to an increase in the rate constant for a reaction: I. Decreasing the temperature II. Decreasing the activation energy III. Making the value of ΔE more negative a. Only one of the statements increases the reaction rate. b. Statements I and II increase the reaction rate. c. Statements I and III increase the reaction rate. d. Statements II and III increase the reaction rate. e. All three statements increase the reaction rate.
a
Which reaction produces an increase in the entropy of the system? a. CO2 (s) → CO2 (g) b. H2 (g) + Cl2 (g) → 2 HCl (g) c. Ag+ (aq) + Cl- (aq) → AgCl (s) d. H2O (l) → H2O (s) e. N2 (g) + 3 H2 (g) → 2 NH3 (g)
a
Which solution will have the highest pH? The Ka of HClO is 3.8 × 10−8. a. A solution of 100 mL of water with 20 mL of 0.1 M NaOH added. b. A 100 mL buffer solution of 0.1 M HClO, 0.1 MClO− with 20 mL of 0.1 M HCl solution added. c. A buffer solution of 0.1 M HClO, 0.1 M ClO−. d. A 100 mL buffer solution of 0.1 M HClO, 0.1 M ClO− with 20 mL of 0.1 M NaOH solution added.
a
2HBr(g)⇌H2(g)+Br2(g);Kc=5.8×10−18 reaction lies a. to the right, favoring the formation of products b. to the left, favoring formation of reactants
b
How does the energy needed to overcome the energy barrier compare with the overall change in energy for this reaction? a. The magnitude of energy needed to overcome the energy barrier is lower than the magnitude of the energy change in the reaction. b. The magnitude of energy needed to overcome the energy barrier is greater than the magnitude of the energy change in the reaction. c. The magnitude of energy needed to overcome the energy barrier is about the same as the magnitude of the energy change in the reaction.
b
If liquid A is more volatile than liquid B, which is also true? a. Liquid A evaporates more slowly than liquid B. b. Liquid A has a lower boiling point than liquid B. c. Liquid A has a lower vapor pressure than liquid B. d. Liquid A has stronger intermolecular forces than liquid B.
b
If the inside surface of each tube were coated with wax, would the general shape of the water meniscus change? Would the general shape of the mercury meniscus change? a. Coating the inside of tube with wax will only change the shape of the mercury meniscus. b. Coating the inside of tube with wax will only change the shape of the water meniscus. c. Coating the inside of tube with wax will not change the shape of the mercury nor water menisci. d. Coating the inside of tube with wax will change the shape of both, the mercury and the water menisci
b
In a linear graphical representation of a zero-order reaction, what value is represented by the y-intercept of the line drawn from plotting [A] vs. time? a. ln[A]0 b. [A]0 c. 1/[A]0 d. [A]02 e. [A]/k
b
Of the units below, ________ are appropriate for a third-order reaction rate constant. a. s−1 b. M−2s−1 c. M−1s−1 d. Ms−1
b
Suppose you are given two flasks at the same temperature, one of volume 2 L and the other of volume 3 L. The 2-L flask contains 4.8 g of gas, and the gas pressure is X atm. The 3-L flask contains 0.36 g of gas, and the gas pressure is 0.1X. Do the two gases have the same molar mass? If not, which contains the gas of higher molar mass? a. yes b. no, 2-L flask contains the gas of higher molar mass c. no, 3-L flask contains the gas of higher molar mass d. not enough information is given
b
The reaction CH3-N ≡ C → CH3-C ≡ N is a first-order reaction. At 230.3°C, k = 6.29 ⋅ 10-4s-1. If [CH3 = N≡C] is 1.00 ⋅ 10-3 initially, [CH3 = N≡C] is ________ after 1.000 ⋅ 103 s. a. 2.34 ⋅ 10-4 b. 5.33 ⋅ 10-4 c. 4.27 ⋅ 10-3 d. 1.00 ⋅ 10-6 e. 1.88 ⋅ 10-3
b
The value of Δ G° for a reaction conducted at 25 °C is 3.05 kJ/mol. The equilibrium constant for a reaction is ________ at this temperature. a. -4.20 b. 0.292 c. -1.13 d. 0.320 e. More information is needed.
b
What is the molecularity of the elementary reaction? NO(g)+Cl2(g)⟶NOCl(g)+Cl(g) a. Unimolecular b. Bimolecular c. Termolecular d. No such reaction will take place.
b
When metallic aluminum is added to a solution containing iron(II) sulfate a reaction occurs. What species is being oxidized in the overall reaction? a. Fe2+(aq) b. Al(s) c. SO42−(aq) d. Al3+(aq)
b
Which of the following mixtures may be act as a buffer solution? a. HCl, NaCl b. HF, NaF c. HBr, NaBr d. HI, NaI
b
Which of the following solutions is a buffer? Check all that apply. a. a solution made by mixing 100 mL of 0.100 M CH3COOH and 500 mL of 0.100 M NaOH b. a solution made by mixing 100 mL of 0.100 M CH3COOH and 50 mL of 0.100 M NaOH c. a solution made by mixing 100 mL of 0.100 M CH3COOH and 50 mL of 0.100 M HCl d. a solution made by mixing 100 mL of 0.100 M CH3COOK and 50 mL of 0.100 M KCl
b
Which of the following statements is false? a. Entropy increases with the number of microstates of the system. b. The change in entropy in a system depends on the initial and final states of the system and the path taken from one state to the other. c. Any irreversible process results in an overall increase in entropy. d. The total entropy of the universe increases in any spontaneous process.
b
A 25.0 mL sample of an acetic acid solution is titrated with a 0.175 M NaOH solution. The equivalence point is reached when 20.6 mL of the base is added. The concentration of acetic acid in the sample was ________ M. a. 0.365 b. 0.175 c. 0.144 d. 0.119 e. none of the above
c
A balloon is inflated to a volume of 5.00 x 102 ml at 22.0 0C. The balloon is then cooled at constant pressure to 0.500 x 102 K. What is the final volume of the balloon? a. 2950 ml b. 29.5 mL c. 84.4 mL d. 840 mL
c
A certain reaction X + Y → Z is described as being first order in [X] and third order overall. Which of the following statements is or are true?: I. The rate law for the reaction is: Rate = k[X][Y]2. II. If the concentration of X is increased by a factor of 1.5, the rate will increase by a factor of 2.25. II. If the concentration of Y is increased by a factor of 1.5, the rate will increase by a factor of 2.25. a. Only one of the statements is true b. Statements I and II are true c. Statements I and III are true d. Statements II and III are true e. All three statements are true
c
A compound decomposes by a first-order process. If 27 % of the compound decomposes in 60 minutes, the half-life of the compound is ________minutes. a. -5 b. -18 c. 132 d. 27 e. 32
c
An aqueous solution of nitric acid contains 70.0 % HNO3 by mass. The density of HNO3 is 1.42 (g/cm3). Express the mass percent of HNO3 in molarity. a. 25.34 mol/L b. 15.8 g/cm3 c. 15.8 mol/L d. .158 mol/L
c
At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen: 2N2O5(g)→4NO2(g)+O2(g) When the rate of formation of O2 is 7.4×10−3 M/s, the rate of decomposition of N2O5 is ________ M/s. a. 3.7×10−3 b. 3.0×10−2 c. 1.5×10−2 d. 7.4×10−3 e. 1.9×10−3
c
Consider the following chemical reaction: CO (g) + 2H2(g) ↔ CH3OH(g) At equilibrium in a particular experiment, the concentrations of CO and H2 were 0.15 M and0.36 M,respectively. What is the equilibrium concentration of CH3OH? The value of Keq for this reaction is 14.5 at the temperature of the experiment. a. 1.34 ⋅ 10-3 b. 7.61 ⋅ 10-3 c. 2.82 ⋅ 10-1 d. 3.72 ⋅ 10-3 e. 14.5
c
For the arbitrary reaction, A + B → C + D the following initial rates were measured given the initial concentrations of A and B. Determine the rate order for both A and B. [A]o [B]o Initial Rate (M/s) 0.12 0.22 0.00639 0.24 0.22 0.0128 0.12 0.11 0.00639 a. 2nd order in A and 0th order in B b. 0th order in A and 1st order in B c. 1st order in A and 0th order in B d. 1st order in A and 1st order in B
c
Given the following table of thermodynamic data, SubstanceTiCl4(g)TiCl4(l)ΔHf°(kJ/mol)−763.2−804.2S°(J/mol⋅K)354.9221.9 complete the following sentence. The vaporization of TiCl4 is ________. a. spontaneous at low temperature and nonspontaneous at high temperature b. nonspontaneous at all temperatures c. nonspontaneous at low temperature and spontaneous at high temperature d. spontaneous at all temperatures e. not enough information given to draw a conclusion
c
Half-reaction E° (V) Cr3+ (aq) + 3e- → Cr (s) -0.74 Fe2+ (aq) + 2e- → Fe (s) -0.440 Fe3+ (aq) + e- → Fe2+ (s) +0.771 Sn4+ (aq) + 2e- → Sn2+ (aq) +0.154 The standard cell potential (E°cell) for the voltaic cell based on the reaction below is ________ V. Sn2+ (aq) + 2Fe3+ (aq) → 2Fe2+ (aq) + Sn4+ (aq) a. +1.21 b. +1.39 c. +0.617 d. +0.46 e. -0.46
c
How many milliliters of 0.0991 M NaOH are required to titrate 25.0 mL of 0.0839 M HBr to the equivalence point? a. 0.333 b. 0.208 c. 21.2 d. 4.58 e. 29.5
c
If ΔG° for a reaction is greater than zero, then ________. a. K = 1 b. K = 0 c. K < 1 d. K > 1 e. more information is needed.
c
The Goodyear blimp contains 5.74×106 L of helium at 25∘C and 1.00 atm. What is the mass in grams of the helium inside the blimp? a. 2.30×107 g b. 2.80×106 g c. 9.39×105 g d. 2.34×105 g e. 1.12×107 g
c
The data in the table below were obtained for the reaction: 2ClO2 (aq) + 2OH- (aq) → ClO3 - (aq) + ClO2 - (aq) + H2O (1) Experiment Number [ClO2] (M) [OH-] (M) Initial Rate (M/s) 1 0.060 0.030 0.0248 2 0.020 0.030 0.00276 3 0.020 0.090 0.00828 What is the magnitude of the rate constant for the reaction? a. 115 b. 4.6 c. 230 d. 1.15 ⋅ 104 e. 713
c
The isomerization of methylisonitrile to acetonitrile CH3NC(g)→CH3CN(g) is first order in CH3NC. The rate constant for the reaction is 2.34×10−4 s−1 at 489 K. The half-life of the reaction when the initial [CH3NC] is 0.030 M is ________ s. a. 2.14×103 b. 3.37×10−4 c. 2.96×103 d. 4.28×103 e. 1.43×105
c
The pH of the equivalence point of a weak acid-strong base titration is _________. a. less than 7 b. equal to 7 c. greater than 7 d. always when equal volumes of acid and base have reacted
c
What happens if a solute is added to a saturated solution? a. The added solute provides a template for the solid to begin to crystallize from solution, and a precipitate will form. b. The added solute provides a template for the gas to begin to boil from solution, and a gas will form. c. Nothing will happen, solute will not mix with a saturated solution. d. The added solute makes the solution less saturated.
c
What is the molecularity of an elementary step, given its rate law is as follows: Rate = k[A]2[B]? a. trimolecular b. bimolecular c. termolecular d. unimolecular
c
What is the pH of 100 mL of a buffer that is 0.5 M HCNO and 0.5 M CNO− when 100 mL of a 0.2 M NaOH solution is added? Assume the volumes are additive. Ka of HCNO is 3.5 × 10−4. a. 4.16 b. 2.76 c. 3.82 d. 3.46
c
What is the pH of a 0.40 M solution of benzoic acid, C6H5COOH? (The Ka value for benzoic acid is 6.3×10−5.) a. 1.90 b. 2.10 c. 2.30 d. 4.20 e. 4.60
c
What is the stoichiometric coefficient for H2O in the balanced redox reaction, and is it a reactant or product? Assume smallest whole number coefficients Al(s) + NO2−(aq) → NH4+(aq) + AlO2 −(aq) a. 0 b. 1, reactant c. 2, reactant d. 1, product e. 2, product f. 4, reactant
c
Which of the following changes will increase the potential of the following electrochemical cell relative to Ecello? Select all that apply. Sn2+(aq) + Cu2+(aq) → Sn4+(aq) + Cu(s) a. Decreasing the size of the solid Cu foil in electrode b. Decreasing [Cu2+] c. Increasing [Sn2+] d. Increasing [Sn4+]
c
A 25.0 mL sample of an HCl solution is titrated with a 0.139 M NaOH solution. The equivalence point is reached with 35.5 mL of base. The concentration of HCl is ________ M. a. 11.7 b. 0.0493 c. 0.00493 d. 0.197 e. 0.139
d
A 25.0-mL sample of 0.150 M formic acid is titrated with a 0.150 M NaOH solution. What is the pH after 13.3 mL of base is added? The Ka of formic acid is 1.8 ⋅ 10-4. a. 3.69 b. 2.54 c. 1.34 d. 3.80 e. 3.47
d
A flask is charged with 0.124 md of A and allowed to react to form B according to the reaction A(g) → B(g). The following data are obtained for [A] as the reaction proceeds: Time (s) 0.00 10.0 20.0 30.0 40.0 Moles of A 0.124 0.110 0.088 0.073 0.054 The average rate of disappearance of A between 10 s and 20 s is ________ mol/s. a. 454 b. 4.4 ⋅ 10-3 c. 9.90 ⋅ 10-3 d. 2.2 ⋅ 10-3 e. 1.1 ⋅ 10-3
d
As the temperature of a reaction is increased, the rate of the reaction increases because the ________. a. reactant molecules collide less frequently and with greater energy per collision b. reactant molecules collide less frequently c. activation energy is lowered d. reactant molecules collide more frequently and with greater energy per collision e. reactant molecules collide more frequently with less energy per collision
d
Calculate the enthalpy change (in joules) involved in converting 5.00 grams of water at 14.0 °C to steam at 115 °C under a constant pressure of 1 atm. The specific heats of ice, liquid water, and steam are, respectively, 2.03, 4.18, 1.84 J/g-K, and for water ΔHfusion = 6.01 kJ/mole and ΔHvap = 40.67 kJ/mole. a. 2.05 × 105 J b. 1.94 × 103 J c. 1.95 × 103 J d. 1.32 × 104 J
d
Consider two gas cylinders of the same volume and temperature, one containing 1.0 mol of propane, C3H8, and the other 2.0 mol of methane, CH4. Which of the following statements is true? a. The gas pressure is the same in both cylinders. b. The rate at which the molecules collide with the cylinder walls is the same for both cylinders. c. The C3H8 and CH4 molecules have the same urms. d. The C3H8 and CH4 molecules have the same average kinetic energy.
d
For an isothermal process, the entropy change of the surroundings is given by the equation: a. Δ S = -q lnT b. Δ S = q lnT c. Δ S = -qsys T d. Δ S = -qsys / T e. Δ S = qsys T
d
For the elementary reaction NO3 + CO → NO2 + CO2 the molecularity of the reaction is ________, and the rate law is rate = ________. a. 4, k[NO2][CO2]/[NO3][CO] b. 2, k[NO2][CO2] c. 2, k[NO3][CO]/[NO2][CO2] d. 2, k[NO3][CO] e. 4, k[NO3][CO][NO2][CO2]
d
Half-reaction E° (V) Cr3+ (aq) + 3e- → Cr (s) -0.74 Fe2+ (aq) + 2e- → Fe (s) -0.440 Fe3+ (aq) + e- → Fe2+ (s) +0.771 Sn4+ (aq) + 2e- → Sn2+ (aq) +0.154 Part A Which of the following reactions will occur spontaneously as written? 3Fe2+ (aq) → Fe (s) + 2Fe3+ (aq) 3Fe (s) + 2Cr3+ (aq) → 2Cr (s) + 3Fe2+ (aq) Sn4+ (aq) + Fe3+ (aq) → Sn2+ (aq) + Fe2+ (aq) 3Sn4+ (aq) + 2Cr (s) → 2Cr3+ (aq) + 3Sn2+ (aq) Sn4+ (aq) + Fe2+ (aq) → Sn2+ (aq) + Fe (s)
d
The equilibrium-constant expression depends on the ________ of the reaction. a. temperature b. mechanism c. the quantities of reactants and products initially present d. stoichiometry e. stoichiometry and mechanism
d
The pH of a solution prepared by mixing 55.0 mL of 0.183 M KOH and 70.0 mL of 0.145 M HC2H3O2 is ________. a. 7.74 b. 10.833 c. 9.97 d. 3.167 e. none of the above
d
The rate constant for a particular second-order reaction is 0.47 M−1s−1. If the initial concentration of reactant is 0.25 mol/L, it takes ________ s for the concentration to decrease to 0.060 mol/L. a. 6.0 b. 1.4 c. 0.06 d. 27 e. 13
d
The value of Keq for the equilibrium H2 (g) + I2 (g) ⇌ 2HI (g) is 54.0 at 427 °C. What is the value of Keq for the equilibrium below? HI (g) ⇌ 1/2 H2 (g) + 1/2 I2(g) a. 2.92 ⋅ 103 b. 27 c. 3.43 ⋅ 10-4 d. 0.136 e. 7.35
d
A compound decomposes by a first-order process. If 26 % of the compound decomposes in 60 minutes, the half-life of the compound is ________minutes. a. 26 b. 31 c. -18 d. -5 e. 138
e
A particular first-order reaction has a rate constant of 1.35 × 102 s−1 at 25.0 ∘C. What is the magnitude of k at 75.0∘C if Ea = 55.5 kJ/mol. a. 3.11 × 1079 b. 435 c. 2.25 × 104 d. 1.35 × 102 e. 3.38 × 103
e
A second-order reaction has a half-life of 12 s when the initial concentration of reactant is 0.98 M. The rate constant for this reaction is ________ M-1s-1. a. 4.3 b. 12 c. 2.0 ⋅ 10-2 d. 4.3 ⋅ 10-2 e. 8.5 ⋅ 10-2
e
A solution is prepared by dissolving 27.7 g of CaCl2 in 375 g of water. The density of the resulting solution is 1.05 g/mL. The concentration of CaCl2 is ________% by mass. a. 7.22 b. 0.0722 c. 6.24 d. 0.0688 e. 6.88
e
At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): (CH3NC)(g)→(CH3CN)(g) At the start of an experiment, there are 0.200 mol of reactant and 0 mol of product in the reaction vessel. After 25 min, 0.115 mol of reactant (CH3NC) remain. There are ________ mol of product (CH3CN) in the reaction vessel. a. 0.315 b. 0.022 c. 0.200 d. 0.115 e. 0.085
e
The Keq for the equilibrium below is 7.52 ⋅ 10-2 at 480.0 °C. 2Cl2 (g) + 2H2O (g) ⇌ 4HCl (g) + O2 (g) What is the value of Keq at this temperature for the following reaction? 12HCl (g) + 3O2 (g) ⇌ 6Cl2 (g) + 6H2O (g) a. 7.52 ⋅ 10-2 b. 0 c. 0.226 d. 4.25×10−4 e. 2350
e
The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction 2N2O5(soln)→4NO2(soln)+O2(soln) The reaction is first order and has a rate constant of 4.82 × 10-3 s−1 at 64 ∘C. If the reaction is initiated with 0.055 mol in a 1.00-L vessel, how many moles remain after 151 s? a. 13 b. 2.1 × 10-3 c. 0.057 d. 0.052 e. 0.027
e
The peroxydisulfate ion (S2O8 2-) reacts with the iodide ion in aqueous solution via the reaction: S2O8 2- (aq) + 3I- → 2SO4 2- + I3 - (aq) An aqueous solution containing 0.050 M of S2O8 2- ion and 0.072 M of I- is prepared, and the progress of the reaction followed by measuring [I-].The data obtained is given the table below. Time (s) 0.000 400.0 800.0 1200.0 1600.0 [I-] (M) 0.072 0.057 0.046 0.037 0.029 The concentration of S2O8 2- remaining at 800 s is ________ M. a. 0.076 b. 0.046 c. 0.015 d. 4.00 ⋅ 10-3 e. 0.041
e
CBr4 has a higher vapor pressure at the same temperature than CCl4. True False
false
The pH of a solution prepared by mixing 50.0 mL of 0.20 M propanoic acid with 50.0 mL of 0.20 M NaOH is 7.00. true or false?
false
Identify the types of intermolecular forces present in C6H14. Dipole-dipole interactions Hydrogen bonding London dispersion forces Ion-dipole interactions
london dispersion forces
Identify the types of intermolecular forces present in C8H18. Hydrogen bonding London dispersion forces Dipole-dipole interactions Ion-dipole interactions
london dispersion forces
Identify the types of intermolecular forces present in C₃H₈. Dipole-dipole interactions London dispersion forces Hydrogen bonding Ion-dipole interactions
london dispersion forces
CBr4 has a higher boiling point than CCl4. True False
true
If the pH of a solution of HCl is the same as a solution of CH3CH2COOH, then the molar concentration of HCl must be less than the molar concentration of the propanoic acid solution. Ka (propanoic acid) = 1.32x10⁻⁵ true or false?
true
The rate limiting step in a reaction is the slowest step in the reaction sequence. true or false
true
A mixture of 1.374 g of H2 and 70.31 g of Br2 is heated in a 2.00 L vessel at 700 K . These substances react as follows: H2(g)+Br2(g)⇌2HBr(g) At equilibrium the vessel is found to contain 0.566 g of H2. 1. Calculate the equilibrium concentration of H2. 2. Calculate the equilibrium concentration of Br2. 3. Calculate the equilibrium concentration of HBr. 4. Calculate Kc.
1. 0.140 M 2. 1.96x10⁻² M 3. 0.401 M 4. 58
For the reaction I2(g)+Br2(g)←−→2IBr(g), Kc=280 at 150 ∘C. Suppose that 0.520 mol IBr in a 2.00-L flask is allowed to reach equilibrium at 150 ∘C. 1. What is the equilibrium concentration of IBr? 2. What is the equilibrium concentration of I2? 3. What is the equilibrium concentration of Br2?
1. 0.232 M 2. 1.39x10-2 M 3. 1.39x10-2 M
At 218 ∘C, Kc=1.2×10−4 for the equilibrium process: NH4SH(s)⇌NH3(g)+H2S(g). 1. Calculate the equilibrium concentration of NH3 if a sample of solid NH4SH is placed in a closed vessel at 218 °C and decomposes until equilibrium ideated. 2. Calculate the equilibrium concentration of H2S if a sample of solid NH4SH is placed in a closed vessel at 218 °C and decomposes until equilibrium is reached>
1. 1.1x10-2 M 2. 1.1x10-2 M
A mixture of 0.10 mol of NO, 0.050 mol of H2, and 0.10 mol of H2O is placed in a 1.0-L vessel at 300 K. The following equilibrium is established: 2NO(g)+2H2(g)⇌N2(g)+2H2O(g) At equilibrium [NO]=0.062M. 1. Calculate the equilibrium concentration of H2. 2. Calculate the equilibrium contraction of N2. 3. Calculate the equilibrium concentration of H2O. 4. Calculate Kc.
1. 1.2x10-2 M 2. 1.9x10-2 M 3. 0.138 M 4. 650
At 2000 ∘C the equilibrium constant for the reaction 2NO(g)⇌N2(g)+O2(g) is Kc=2.4×103. 1. If the initial concentration of NO is 0.175 M, what is the equilibrium concentration of NO? 2. If the initial concentration of NO is 0.175 M, what is the equilibrium concentration of N2? 3. If the initial concentration of NO is 0.175 M, what is the equilibrium constant of O2?
1. 1.8x10-3 M 2. 8.7x10-2 M 3. 8.7x10-2 M
For a particular reaction, ΔH = -30 kJ and ΔS = -95 J/K . Assume that ΔH and ΔS do not vary with temperature. 1. At what temperature will the reaction have ΔG = 0? 2. If T is increased from that in part 1, will the reaction be spontaneous or nonspontaneous?
1. 320 K 2. nonspontaneous
Phenylacetic acid (C6H5CH2COOH) is one of the substances that accumulates in the blood of people with phenylketonuria, an inherited disorder that can cause mental retardation or even death. A 0.085 M solution of C6H5CH2COOH has a pH of 2.68. 1. Calculate the Ka value for this acid.
1. 5.3x10⁻⁵
Predict the stronger acid. 1. HCl or HF 2. H₃PO₄ or H₃AsO₄ 3. HBrO₃ or HBrO₂ 4. H₂C₂O₄ or HC₂O₄⁻ 5. C₆H₅OH or C₆H₅COOH
1. HCl 2. H₃PO₄ 3. HBrO₃ 4. H₂C₂O₄ 5. C₆H₅COOH
The hydrogen sulfite ion (HSO3−) is amphiprotic. 1. Write a balanced chemical equation showing how it acts as an acid toward water. 2. Write another equation showing how it acts as a base toward water. 3. What is the conjugate acid of HSO₃⁻? 4. What is the conjugate base of HSO₃⁻?
1. HSO₃⁻ + H₂O ⇌ SO₃²⁻ + H₃O⁺ 2. HSO₃⁻ + H₂O ⇌ H₂SO₃ + OH⁻ 3. H₂SO₃ 4. SO₃²⁻
Based on their compositions and structures and on conjugate acid-base relationships, select the stronger base in each of the following pairs. 1. NO₃⁻ or NO₂⁻ 2. HCO₃⁻ or CO₃²⁻
1. NO₂⁻ 2. CO₃²⁻
Predict the products of the following acid-base reactions, and predict whether the equilibrium lies to the left or to the right of the reaction arrow. 1. O²⁻ + H₂O ⇌ 2. Predict whether the equilibrium lies to the left or to the right of the equation in previous part. a. H2O is a stronger acid than OH-, so the equilibrium lies to the right. b. H2O is a weaker acid than OH-, so the equilibrium lies to the left. c. H2O is a stronger acid than OH-, so the equilibrium lies to the left. d. H2O is a weaker acid than OH-, so the equilibrium lies to the right. 3. CH₃COOH + HS⁻ ⇌ 4. Predict whether the equilibrium lies to the left or to the right of the equation in previous part. a. CH3COOH is a weaker acid than H2S, so the equilibrium lies to the left. b. CH3COOH is a stronger acid than H2S, so the equilibrium lies to the left. c. CH3COOH is a weaker acid than H2S, so the equilibrium lies to the right. d. CH3COOH is a stronger acid than H2S, so the equilibrium lies to the right.
1. O²⁻ + H₂O ⇌ 2OH⁻ 2. a 3. CH₃COOH + HS⁻ ⇌ H₂S + CH₃COO⁻ 4. d
The normal boiling point of Br2(l) is 58.8 ∘C, and its molar enthalpy of vaporization is ΔHvap = 29.6 kJ/mol. 1. When Br2 (l) boils at its normal boiling point, does its entropy increase or decrease? 2. Calculate the value of ΔS when 1.90 mol of Br2 (l) is vaporized at 58.8 °C
1. increase 2. 169 J/K
How do the following changes affect the value of the equilibrium constant for a gas-phase exothermic reaction: (decrease, no effect, increase) 1. removal of reactant 2. removal of product 3. decrease in temperature 4. addition of catalyst
1. no effect 2. no effect 3. no effect 4. no effect
As shown here, one type of computer keyboard cleaner contains liquefied 1,1-difluoroethane (C2H4F2), which is a gas at atmospheric pressure. When the nozzle is squeezed, the 1,1-difluoroethane vaporizes out of the nozzle at high pressure, blowing dust out of objects. 1. Based on your experience, is the vaporization a spontaneous process at room temperature? 2. Defining the 1,1-difluoroethane as the system, do you expect sys for the process to be positive or negative? 3. Predict whether delta-S is positive or negative for this process. 4. Given your answers to parts A, B, and C do you think the operation of this product depends more on heat flow or more on entropy change?
1. spontaneous 2. positive 3. positive 4. entropy change
Calculate [H+] for a solution in which [OH−] is 100 times greater than [H+].
1.0x10⁻⁸ M
Calculate [H+] for [OH−]=8.1×10−9 M.
1.2x10⁻⁶ M
Given the equilibrium constant values N₂(g)+12O₂(g)⇌N₂O(g) KC=2.7×10⁻¹⁸ N₂O₄(g)⇌2NO₂(g)KC=4.6×10⁻³ 12N₂(g)+O₂(g)⇌NO₂(g)KC=4.1×10⁻⁹ Determine a value of KC for the reaction 2N₂O(g)+3O₂(g)⇌2N₂O₄(g)
1.8x10⁶
For the equilibrium Br2(g)+Cl2(g)⇌2BrCl(g) at 400 K, Kc = 7.0. If 0.25 mol of Br2 and 0.55 mol of Cl2 are introduced into a 3.0-L container at 400 K, what will be the equilibrium concentration of Br2?
1.9x10-2 M
What is the pH of a 7.5 × 10-3 M Ba(OH)2 solution at 25°C?
12.18
Calculate [H+] for [OH−]=5.1×10−4 M.
2.0x10⁻¹¹ M
Calculate the Kb value for CH3COO−. Ka for acetic acid is 1.8×
3.3x10⁻⁷
Ka for benzoic acid is 6.3×10−5. What is the first digit of the pKa value for benzoic acid?
4
A mixture initially contains A, B, and C in the following concentrations: [A] = 0.500 M , [B] = 1.15 M , and [C] = 0.700 M . The following reaction occurs and equilibrium is established: A+2B⇌C At equilibrium, [A] = 0.320 M and [C] = 0.880 M . Calculate the value of the equilibrium constant, Kc.
4.41
At 1285 ∘C the equilibrium constant for the reaction Br2(g)⇌2Br(g) is Kc=1.04×10−3. A 0.200-L vessel containing an equilibrium mixture of the gases has 0.243 g Br2(g) in it. What is the mass of Br(g) in the vessel?
4.49x10-2 g
During a certain reversible process, the surroundings undergo an entropy change, ΔSsurr = - 79 J/K . What is the entropy change of the system for this process?
79 J/K
Select the substance that has the higher boiling point. C₃H₈ CH₃OCH₃
CH₃OCH₃
C6H5COOH. Show the reaction with H+(aq) as a product.
C₆H₅COOH ⇌ H⁺ + C₆H₅COO⁻
Select the substance that has the higher boiling point. C₆H₁₄ C₈H₁₈
C₈H₁₈
Identify the types of intermolecular forces present in HOOH. Dipole-dipole interactions London dispersion forces Hydrogen bonding Ion-dipole interactions
Dipole-dipole interactions London dispersion forces Hydrogen bonding
Identify the types of intermolecular forces present in HSSH. London dispersion forces Ion-dipole interactions Dipole-dipole interactions Hydrogen bonding
London dispersion forces Dipole-dipole interactions
dentify the types of intermolecular forces present in NH2NH2. Check all that apply. London dispersion forces Hydrogen bonding Ion-dipole interactions Dipole-dipole interactions
London dispersion forces Hydrogen bonding Dipole-dipole interactions
An unknown salt is either NaF, NaCl, or NaOCl. When 0.050 mol of the salt is dissolved in water to form 0.500 L of solution, the pH of the solution is 8.08. What is the identity of the salt? NaF NaCl NaOCl
NaF
At the freezing point of water (0∘C), Kw=1.2×10−15. Calculate [H+] and [OH−] for a neutral solution at this temperature.
[H⁺] = 3.5x10⁻⁸ M [OH⁻] = 3.5x10⁻⁸ M
Determine the equilibrium constant, K, at 25°C for a reaction in which ΔGo = −20.5 kJ/mol. a. 3.92 × 103 b. 1.01 c. 6.82 × 1042 d. 1.88 × 108
a
Given that the Ka for acetic acid is 1.8×10−5 and the Ka for hypochlorous acid is 3.0×10−8, which is the stronger acid? a. acetic acid b. hypochlorous acid
a
In a particular spontaneous process the entropy of the system decreases. What can you conclude about the sign and magnitude of ΔSsurr? a. ΔSsurr is positive and greater than the magnitude of the decrease inΔSsys. b. ΔSsurr is negative and less than the magnitude of the decrease in ΔSsys. c. ΔSsurr is negative and greater than the magnitude of the decrease in ΔSsys. d. ΔSsurr is positive and less than the magnitude of the decrease in ΔSsys.
a
List the substances Ar, Cl2, CH4, and CH3COOH, in order of increasing strength of intermolecular attractions. a. CH4 < Ar < Cl2 < CH3COOH b. Ar < Cl2 < CH4 < CH3COOH c. CH3COOH < Cl2 < Ar < CH4 d. CH4 < Ar< CH3COOH < Cl2 e. Cl2 < CH3COOH < Ar < CH4
a
Select each process that produces an increase in the entropy of the system: Check all that apply. a. CO2(s) → CO2(g) b. CaO(s) + CO2(g) → CaCO3(s) c. HCl(g) + NH3(g) → NH4Cl(s) d. 2 SO2(g) + O2(g) → 2 SO3(g)
a
The benzoate ion, C6H5COO− is a weak base with Kb=1.6×10−10. How many moles of sodium benzoate are present in 0.50 L of a solution of NaC6H5COO if the pH is 9.04? a. 0.38 b. 0.66 c. 0.76 d. 1.5 e. 2.9
a
Which correctly lists the following in order of increasing entropy? i. 1 mol of HCl (g) at 50 ° C ii. 1 mol of NaCl (s) at 25 ° C iii. 2 mol of HCl (g) at 50 ° C iv. 1 mol of HCl (g) at 25 ° C a. ii. < iv. < i. < iii. b. iii. < i. < iv. < ii. c. ii. < iv. < iii. < i. d. iv. < ii. < i. < iii.
a
Which of the following conjugate acid-base pairs will function as a buffer? a. HF/F- b. H2O/OH- c. HBr/OH- d. HCl/Cl-
a
Which of the following reactions lies to the right, favoring the formation of products, and which lies to the left, favoring formation of reactants? 2NO(g)+O2(g)⇌2NO2(g);Kp=5.0×1012 reaction lies a. to the right, favoring the formation of products b. to the left, favoring formation of reactants
a
Consider the equilibrium that is established in a saturated solution of silver chloride, Ag+(aq) + Cl−(aq) ⇌ AgCl(s). If solid AgCl is added to this solution what will happen to the concentration of Ag+ and Cl− ions in solution? a. [Ag+] and [Cl−] will both decrease b. neither [Ag+] nor [Cl−] will change c. [Ag+] will decrease and [Cl−] will increase d. [Ag+] will increase and [Cl−] will decrease e. [Ag+] and [Cl−] will both increase
b
Consider two gas cylinders of the same volume and temperature, one containing 1.0 mol of propane, C3H8, and the other 2.0 mol of methane, CH4. Which of the following statements is true? a. The gas pressure is the same in both cylinders. b. The C3H8 and CH4 molecules have the same average kinetic energy. c. The C3H8 and CH4 molecules have the same urms. d. The rate at which the molecules collide with the cylinder walls is the same for both cylinders.
b
Determine the equilibrium-constant expression for the reaction: 2NBr3 (s) ↔ N2 (g) + 3Br2 (g) ? a. K = [NBr3]2 b. K = [N2][Br2]3 c. K = [N2][Br2]3/[NBr3]2 d. K = [NBr3]2 /[N2][Br2]3
b
For the reaction below at 25 0C ΔG= -354 kJ/mol, determine the value of ΔG at 1727 0C and state if the reaction remains spontaneous. P4O10(s)+6H2O(l)→4H3PO4(s) where: ΔH0f [P4O10(s)]= -2984 kJ/mol ΔH0f [H2O(l)]= -286 kJ/mol ΔH0f [H3PO4(s)]= -1279 kJ/mol S0 [P4O10(s)]= 229 J/ K mol S0 [H2O(l)]= 70 J/ K mol S0 [[H3PO4(s)]= 229 J/ K mol a. ΔG=+200 kJ/mol, the reaction is spontaneous in the forward direction at this temperature. b. ΔG=+2.0 kJ/mol, the reaction is no longer spontaneous in the forward direction at this temperature. c. ΔG=-0.20 kJ/mol, the reaction is no longer spontaneous in the forward direction at this temperature. d. ΔG=-200 kJ/mol, the reaction is no longer spontaneous in the forward direction at this temperature.
b
If a reaction is exothermic and its entropy change is positive, which statement is true? a. The reaction is nonspontaneous at all temperatures. b. The reaction is spontaneous at all temperatures. c. The reaction is spontaneous only at lower temperatures. d. The reaction is spontaneous only at higher temperatures.
b
In liquids, the attractive intermolecular forces are ________. a. strong enough to hold molecules relatively close together b. strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other c. not strong enough to keep molecules from moving past each other d. strong enough to keep the molecules confined to vibrating about their fixed lattice points e. very weak compared with kinetic energies of the molecules
b
In which direction is this process exothermic? a. the melting of ice to liquid water b. the freezing of liquid water to ice
b
Now consider the reaction A+2B⇌C for which in the initial mixture Qc=[C][A][B]2=387 Is the reaction at equilibrium? If not, in which direction will it proceed to reach equilibrium? a. The reaction is already at equilibrium. b. The reaction will proceed in reverse to form reactants. c. The reaction will proceed forward to form products.
b
The Ka of NH4+ is 5.6 × 10−10. The Kb of CN− is 2 × 10−5. The pH of a salt solution of NH4CN would be: a. Less than 7 because CN− is a stronger base than NH4+ is an acid. b. Greater than 7 because CN− is a stronger base than NH4+ is an acid c. Greater than 7 because NH4+ is a stronger acid than CN− is a base. d. Less than 7 because NH4+ is a stronger acid than CN− is a base.
b
The equilibrium constant, K c, for the reaction H2 (g) + I2 (g) ⇄ 2HI (g) at 425°C is 54.8. A reaction vessel contains 0.0890 M HI, 0.215 M H2, and 0.498 M I2. Which statement is correct about this reaction mixture? a. The reaction is not at equilibrium and will proceed to make more reactants to reach equilibrium. b. The reaction is not at equilibrium and will proceed to make more products to reach equilibrium. c. The reaction quotient is greater than 1. d. The reaction mixture is at equilibrium.
b
The equilibrium constant, Kc, for the reaction H2 (g) + I2 (g) ⇄ 2HI (g) at 425°C is 54.8. A reaction vessel contains 0.0890 M HI, 0.215 M H2, and 0.498 M I2. Which statement is correct about this reaction mixture? a. The reaction is not at equilibrium and will proceed to make more reactants to reach equilibrium. b. The reaction is not at equilibrium and will proceed to make more products to reach equilibrium. c. The reaction quotient is greater than 1. d. The reaction mixture is at equilibrium.
b
Using thermodynamic data, calculate the equilibrium constant at 25 0C for the following reaction NO(g)+O3(g)↔NO2(g)+O2(g) where: ΔG0f [NO(g)]= 87 kJ/mol ΔG0f [O3(g)]= 163 kJ/mol ΔG0f [NO2(g)]= 52 kJ/mol ΔG0f [O2(g)]= 0.0 kJ/mol a. 3.0 × 103 b. 5.1 × 1034 c. 2.0 × 10-35 d. 2.2
b
What type of intermolecular force accounts for the following differences in each case? Xe is liquid at atmospheric pressure and 120 K, whereas Ar is a gas. a. London dispersion forces. b. Dipole-dipole bonding. c. Hydrogen bonding. d. Ion-dipole bonding.
b
Which equation is an expression of the second law of thermodynamics for a spontaneous process? a. ΔSuniv = ΔSsys + ΔSsurr < 0 b. ΔSuniv = ΔSsys + ΔSsurr > 0 c. ΔHuniv = ΔHsys + ΔHsurr < 0 d. ΔSuniv = ΔSsys + ΔSsurr = 0
b
Which is the stronger base, the acetate ion or the hypochlorite ion? a. acetate ion b. hypochlorite ion
b
Order the following three solutions from smallest to largest pH: I. 0.20 M HClO3 II. 0.0030 M HNO3 III. 1.50 M HCl a. I < II < III b. II < I < III c. III < I < II d. II < III < I e. III < II < I
c
What is the entropy change of the system when 17.5 g of liquid benzene (C6H6) evaporates at the normal boiling point? The normal boiling point of benzene is 80.1°C and ΔHvap is 30.7 kJ/mol. a. 25.2 J/K b. -19.5 J/K c. +19.5 J/K d. +85.9 J/K
c
What is the pH of a 0.65 M solution of pyridine, C5H5N? (The Kb value for pyridine is 1.7×10−9) a. 4.48 b. 8.96 c. 9.52 d. 9.62 e. 9.71
c
What is the pH of a buffer that is 0.6 M HF and 0.2 M NaF? The Ka of HF is 6.8 × 10−4. a. 3.17 b. 3.50 c. 2.69 d. 3.65
c
What is the pH of a buffer that was prepared by adding 3.96 g of sodium benzoate, NaC7H5O2, to 1.00 L of 0.0100 M benzoic acid, HC7H5O2? Assume that there is no change in volume. The Ka for benzoic acid is 6.3 × 10-5. a. 0.439 b. 4.33 c. 4.64 d. 3.76
c
What is the pH range of most buffer systems? a. ±4 pH unit of pKa b. ±3 pH unit of pKa c. ±1 pH unit of pKa d. ±2 pH unit of pKa
c
What type of intermolecular force accounts for the following differences in each case? CH₃OH boils at 65°C, CH₃SH boils at 6°C. a. London dispersion forces. b. Dipole-dipole bonding. c. Hydrogen bonding. d. Ion-dipole bonding.
c
According to the equation below, which of the following will cause the concentration of H2SO4 to increase? 2NaHCO3 (s) + H2SO4 (aq) ⇄ Na2SO4 (aq) + 2H2O (l) + 2CO2 (g) a. removal of some H2O (l) b. removal of some CO2 (g) c. addition of some NaHCO3 (s) d. addition of some Na2SO4 (aq)
d
Arrange the following substances in order from weakest to strongest acid: HClO3, HOI, HClO3, HBrO2, HClO2, HIO2 a. HIO2 < HOI < HClO3 < HBrO2 < HClO2 b. HClO3 < HClO2 < HBrO2 < HIO2 < HOI c. HBrO2 < HIO2 < HClO2 < HOI < HClO3 d. HIO < HIO2 < HBrO2 < HClO2 < HClO3 e. HOI < HClO2 < HBrO2 < HIO2 < HClO3
d
At 25°C, the following data were collected: Solution A: pH = 8.46 Solution B: pOH = 9.30 Solution C: [H+] = 2.5 × 10-4 M Solution D: [OH-] = 1.1 × 10-10 M Which lists the solutions in order of increasing acidity? a. A < B < C < D b. C < D < A < B c. B < A < D < C d. A < B < D < C
d
Determine the pH of 0.57 M methylamine (CH3NH2) with Kb = 4.4 x 10-4 : CH3NH2(aq)+ H2O(l)↔CH3NH3+ (aq) + OH- (aq) a. pH = 112 b. pH = 1.2 c. pH = 0.12 d. pH = 12.2
d
Given that Kc of the reaction below is 2.2 × 10-3 at a certain temperature, which of the following statements is correct? 2ICl (g) ⇄ I2 (g) + Cl2 (g) a. At this temperature, the products are favored and the equilibrium lies to the right. b. At this temperature, the products are favored and equilibrium lies to the left. c. At this temperature, the reactants are favored and the equilibrium lies to the right. d. At this temperature, the reactants are favored and the equilibrium lies to the left.
d
Order the following solutions from lowest to highest pH: 0.10 M NaClO 0.10 M KBr 0.10 M NH4ClO4 a. II < I < III b. I < II < III c. III < I < II d. III < II < I e. II < III < I
d
The equilibrium constant, Kc, for the reaction N2O4 (g) ⇄ 2NO2 (g) is 0.211 at 100°C. If the equilibrium concentration of N2O4 is 0.00251 M, calculate the equilibrium concentration of NO2. a. 5.30 × 10-4 M b. 2.65 × 10-4 M c. 2.99 × 10-5 M d. 0.0230 M
d
A solution at 25 ∘C has pOH = 10.53. Which of the following statements is or are true? I. The solution is acidic. II. The pH of the solution is 14.00 - 10.53. III. For this solution, [OH−] = 10−10.53 M. a. Only one of the statements is true. b. Statements I and II are true. c. Statements I and III are true. d. Statements II and III are true. e. All three statements are true.
e
Consider the reaction: FeO (s) + Fe (s) + O2(g) → Fe2O3 (s) Given the following table of thermodynamic data at 298 K: Substance ΔHf° (kJ/mol) S° (J/K⋅mol) FeO (s) -271.9 60.75 Fe (s) 0 27.15 O2 (g) 0 205.0 Fe2O3 (s) -822.16 89.96 The value K for the reaction at 25 °C is ________. a. 5.9 ⋅ 104 b. 370 c. 3.8 ⋅ 10-14 d. 8.1 ⋅ 1019 e. 7.1 ⋅ 1085
e
The Ksp for a very insoluble salt is 4.2×10−47 at 298 K. What is ΔG∘ for the dissolution of the salt in water? a. -265 kJ/mol b. -115 kJ/mol c. -2.61 kJ/mol d. +115 kJ/mol e. +265 kJ/mol
e
The kinetic-molecular theory predicts that pressure rises as the temperature of a gas increases because ________. a. the gas molecules collide more energetically with the wall b. the gas molecules collide less frequently with the wall c. the average kinetic energy of the gas molecules decreases d. the gas molecules collide more frequently with the wall e. both the gas molecules collide more frequently with the wall and the gas molecules collide more energetically with the wall
e
Using the table below, place the following equilibria in order of smallest to largest value of Kc: I. CH3COOH(aq) + HS−(aq) ⇌ CH3COO−(aq) + H2S(aq) II. F−(aq) + NH4+(aq) ⇌ HF(aq) +NH3(aq) III. H2CO3(aq) + Cl−(aq) ⇌ HCO3−(aq) + HCl(aq) a. I < II < III b. II < I < III c. III < I < II d. II < III < I e. III < II < I
e
________ are particularly polarizable. a. Small nonpolar molecules b. Large nonpolar molecules c. Large polar molecules d. Small polar molecules e. Large molecules, regardless of their polarity,
e
CBr4 has weaker intermolecular forces than CCl4. True False
false
CBr4 is more volatile than CCl4. True False
false
What major type of attractive interaction must be overcome for water to evaporate? ion-dipole interaction dispersion forces hydrogen bonds dipole-dipole interaction
hydrogen bonds
Identify the types of intermolecular forces present in CH₃OCH₃. London dispersion forces Dipole-dipole interactions Hydrogen bonding Ion-dipole interactions
london dispersion forces and dipole-dipole interactions
Does the entropy of the surroundings increase for spontaneous processes? Yes. No. Not necessarily.
not necessarily
The active ingredient in aspirin is acetylsalicylic acid (HC9H7O4), a monoprotic acid with a Ka of 3.3×10−4 at 25 ∘C . What is the pH of a solution obtained by dissolving two extra-strength aspirin tablets, containing 590 mg of acetylsalicylic acid each, in 220 mL of water?
pH = 2.53