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1. According to the Bronsted—Lowry definition, which chemical species can function both as an acid and as a base? a. Cl— b. SO 4 2— c. NH 4 + d. HCO 3 — e. H 3 O+2. In the reaction CN— + H 2 O !" HCN + OH— which is an acid—base conjugate pair? a. H 2 O and HCN b. H 2 O and OH— c. CN— and H ...

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General Chemistry II Sample Test bank

1. According to the Bronsted—Lowry definition, which chemical species can function both as an acid and as a base? a. Cl— b. SO42— c. NH4+ d. HCO3— e. H3O+ 2. In the reaction CN— + H2O !" HCN + OH— which is an acid—base conjugate pair? a. H2O and HCN b. H2O and OH— c. CN— and H2O d. HCN and OH— 3. Given that HX is a stronger Bronsted acid than HY in aqueous solution, which is true of a 1 M solution of NaX a. It is less basic than a 1 M solution of NaY. b. It is more basic than a 1 M solution of NaY. c. It yields a neutral solution. d. It is more concentrated than a 1 M solution of NaY. 4. The pH of a 0.03 M HCl solution is a. 1.5 b. 2.5 c. 3.5 d. 12.5 5. The pH of a 1.0 x 10—3 M Ba(OH)2 solution at 25oC is a. 2.7 b. 3.0 c. 11.0 d. 11.3 6. Which is the strongest acid? a. b. c. d.

HClO HClO2 HClO3 HClO4

7. Which salt reacts with water (hydrolyzes) to produce a basic solution? a. b. c. d.

NaC2H3O2 NaNO3 NH4Cl BaSO4

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8. The weakest of the bases listed is Acid HCl HSO4— H 2S HS— a. Cl— b. CN— c. HS— d. S2— e. SO4 2—

Conjugate Base Cl— SO4 2— HS— S2—

Ka (Ionization Constant of Acid) 100% ionized 1.2 x 10-2 5.7x10-8 1.2x10-13

9. The oxide of which element will react with water to form the strongest acid?

Period First Second Third a. b. c. d. e.

Main Groups I II II IV I X W

Y

Z

P

V

VI VII

O

Q R

U M

S T

W M P R Z

10. Which statement is a logical inference from the fact that a 0.10 M solution of potassium acetate KC2H3O2, is less alkaline than a 0.10 M solution of potassium cyanide, KCN? a. b. c. d.

Hydrocyanic acid is a weaker acid than acetic acid. Hydrocyanic acid is less soluble in water than acetic acid. Cyanides are less soluble than acetates Acetic acid is a weaker acid than hydrocyanic acid

11. In the titration of 50.0 mL of 0.100 M benzoic acid (a monoprotic acid) with 50.0 mL of 0.100 M NaOH, the properties of the solution at the equivalence point will correspond exactly to the properties of a. a 0.100 M sodium solution. b. a 0.0500 M sodium hydroxide solution. c. a 0.0500 M benzoic acid solution. d. a 0.0500 M sodium benzoate solution.

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12. A mixture of which pair of 0.1 M aqueous solutions would constitute a buffer? a. NaOH and NaCl b. HCl and NaOH c. HCl and NaCl d. NH3 and NH4NO3 What do these have in common? 20 24 Ne 19F1Mg2+

13.

a. b. c. d.

the same number of protons the same number of neutrons the same number of electrons the same size

14. The number of neutrons in the nucleus of an atom of 1327Al is a. 40 b. 13 c. 27 d. 14 e. 9 15. The orbitals of 2p electrons are often represented as being a. elliptical. b. Pyramidal c. Tetrahedral d. dumbbell shaped e. spherical. 16. The element in Period 5, Group 3A, has the outer electron configuration a. 5s25p1 b. 3s23p5 c. 3s23p3 d. 5s25p3 17. Which electron impossible? a. 1s22s22p63s2 b. 1s22s22p63s23p6 c. 1s22s22p62d2 d. 1s22s22p53s1

configuration

is

18. The element X occurs naturally to the extent of 20.0% 12X and 80.0% 13X. The atomic mass of X is nearest a. b. c. d.

12.2 12.5 12.8 13.0

19. Which electron transition is associated with the largest emission of energy? a. b. c. d.

n=2 to n=1 n=2 to n=4 n=2 to n=3 n=3 to n=2

20. If an electron moves from one energy level in an atom to another energy level more remote from the nucleus of the same atom a. energy is absorbed. b. energy is liberated. c. there is no energy change. d. the atom must assume a different ionic valence e. light of a definite wave length is emitted. 21. A photon of light of 450 nm, when compared to light of wavelength 300 nm, has (1nm = 10-9 m) a. b. c. d.

a higher frequency. lower energy. a greater velocity. a shorter wavelength

22. Which set of quantum numbers is possible for an electron in an atom? a. b. c. d.

n=3, l=0, ml=1, ms = -½ n=2, l=2,ml= -2, ms = -½ n=5, l=2, ml=2, ms =+½ n=4, l=3, ml= -4, ms= -½

23. A compound consisting of an element having a low ionization potential and a second element having a high electron affinity is likely to have a. b. c. d.

covalent bonds metallic bonds coordinate covalent bonds ionic bonds.

24. According to modern bonding theory the number of sigma ( ) and pi ( ) bonds in the ethylene molecule H2C=CH2 is a. l and 4 b. l and 1 c. l and 5 d. 2 and 4 e. l and 6

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25. a. b. c. d.

The number of 1 2 3 4

bonds in N=N is

26. The elements in an ionic compound are held together by a. b. c. d. e.

electrostatic forces of attraction. van der Waals forces the spin of paired electrons. the formation of hybrid orbitals. an electron pair.

27. In every electrolytic and galvanic (voltaic) cell the anode is that electrode a. b. c. d.

at which oxidation occurs. which attracts cations. at which electrons are supplied to the solution. at which reduction occurs.

28. Metal X was plated from a solution containing cations of X. The passage of 48.25 C deposited 31 mg of X on the cathode. What is the mass of X (in grams) per mole of electrons? a. 47 b. 62 c. 93 d. 186 29. In a galvanic (voltaic) cell in which the reaction is Cd + Cu2+ " Cu + Cd2+ and the ions are at unit concentration (activity), the cell potential is Cd " Cd2++ 2eCu " Cu2+ + 2ea. 0.1383 V b. 0.4021 V c. 0.344 V d. 0.7461 V e. 0.3677 V

0.4021 V - 0.344 V

30. In which reaction will an increase in total pressure at constant temperature favor formation of the products? a. CaCO3(s) !" CaO(s) + CO2(g) b. H2(g) + Cl2(g) !" " 2HCl(g) c. 2NO(g) + O2(g) !" 2NO2(g) d. COCl2(g) !" CO(g) + Cl2(g)

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Standard Potentials Eo 2+ Mg" Mg +2e 2.37V Al " Al3+ +3e 1.66V Zn " Zn2++2e 0.76V Fe"Fe2++2e 0.44V Cu " Cu2++2e 0.34V Ag" Ag++ e -0.80V 31. Using only the metals Mg, Al, Zn, Fe, Cu and Ag, together with their 1 M salt solutions, a voltaic cell of the highest possible voltage would be constructed using electrodes of these metals. a. Mg and Ag b. Mg and Fe c. Zn and Cu d. Al and Ag e. Mg and Al 32. E = Eo - 0.059/n log Q (Nernst equation) + [H ] = 1.0 M initially, P02 = 1.0 atm 4e + O2(g)+4H+(aq)!" 2H2O(l) Eo=1.23V Based on the information above, which statement is correct? a. b. c. d.

n = 1, since one mole of oxygen is being considered. Addition of base should result in an E value, which is less than 1.23 V. E is independent of the pH of the solution. Q = [H2O]2 [O2] [H+]

33. The equilibrium constant for the gaseous reaction C + D !" E + 2F is 3.0 at 50 oC. In a 2.0 L flask at 50 oC are placed 1.0 mol of C, 1.0 mol of D, 1.0 mol of E, and 3.0 mol of F. Initially, the reaction will a. proceed at equal rates in both directions. b. proceed more rapidly to form E and F. c. proceed more rapidly to form C and D. d. not occur in either direction. Compound Go f kJ/mol H2O(l) —237 H2O(g) —229 34. At 298 K the equilibrium constant for H2(g) + ½ O2(g)!" H2O(l) a. b. c.

is larger than the Keq for H2(g) + ½ O2(g)!" H2O(g) will have a value of 1 0 at equilibrium. cannot be computed since data on O2 and

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d.

H2 are not provided. will have the same value as the Keq for 2 H2(g) + O2(g)!" 2 H2O(l)

35. Consider the reversible system at equilibrium: 2CO + O2 !" 2CO2 + heat When the temperature is increased at constant pressure a. b. c. d. e.

the CO2 concentration will be increased. the CO2 concentration will be decreased. the amount of each substance will be unchanged. the amount of each substance will be increased. the result cannot be predicted from the information given.

36. The numerical value of the equilibrium constant for any chemical change is affected by changing a. the catalyst. b. the concentration of the products. c. the concentration of reacting substances. d. the pressure. e. the temperature 37. What is the equilibrium constant expression for the gas phase oxidation of CO to CO2 by O2? a.

K = [CO2]2 [CO][O2]

b.

K= [CO]2 [O2] [CO2]

c.

K= [CO2]2 [CO]2 [O2]

d.

K= [CO] [O2] [CO2]

38. Into an empty vessel COCl2(g) is introduced at 1.0 atm pressure whereupon it dissociates until equilibrium is established: 2COCl2(g) !" C(graphite) +CO2(g) + 2Cl2(g)

a.

If x represents the partial pressure of CO2(g) at equilibrium, what is the value of the equilibrium constant, Kp? x.2x2 (1.0-2x)2

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b. c. d.

x x 2x2 (1.0-2x2) x (2x)2 (1.0- 2x)2 x (2x)2 (1.0—x)2

39. At a certain temperature, the equilibrium constant for the reaction 2HI(g) !" " H2(g) + I2(g) is 0.49. Calculate the number of moles of hydrogen produced when one mole of HI is placed in a 1 L vessel at this temperature. a. 0.41 b. 0.25 c. 0.29 d. 3.45 40. What is the [OH-] of a solution which is 0.18 M in ammonium ion and 0.10 M in ammonia? Kb = 1.8 x 10-5 a. 1.3x10-3 b. 1.0x10-3 c. 1.3x10-5 d. 1.0x10-5 41. What is the pH of a 0.10 M solution of a monoprotic acid, HA, with a Ka = 1.0 x 10-6? a. 1.6 b. 3.5 c. 5.0 d. 6.0 42. When 0.10 mol of a weak acid HA was diluted to one liter, experiment showed the acid to be 1% dissociated. HA + H2O !" H3O+ + AWhat is the acid dissociation constant, Ka? a. 1 x10-6 b. 1 x10-5 c. l x10-3 d. 1 x105 43. Which solution has a pH less than 7.0? a. 1 M NH4Cl b. 1 M K2CO3 c. 1 M NaOCl d. 1 M NaOH 44. What is the pH of a 0.1 M NaF solution? Ionization constant for HF, Ka = 7 x 10-4 a. 2.1 b. 5.9 c. 8.1 d. 9.1

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45. What is the hydrogen ion concentration of a buffer solution containing 0.10 M NO21- and 0.20 M HNO2? Ionization constant for Nitrous Acid, Ka = 4.5x 10-4 a. b. c. d.

2.2x10-4M 9.0 x 10-4 M 4.5 x 10-4 M 9.5 x 10-3M

46. The solubility of BaCO3 is 7.9 x 10-3 g/L. Calculate the solubility product, Ksp ignoring hydrolysis. MW of BaCO3 197 g/mol a. b. c. d.

1.6x10-2 1.6x10-9 4.0x10-5 6.2x10-5

47. The addition of solid Na2SO4 to an aqueous solution in equilibrium with solid BaSO4 will cause a. b. c. d.

no change in [Ba2+] in solution. more BaSO4 to dissolve. precipitation of more BaSO4. an increase in the Ksp of BaSO4.

48. Assume that standardized aqueous solutions of each of these are available. Substance Ionization Constant NaOAc Kb = 5.6 x 10-10 + RNH3 Cl Ka = 5.6 x 10-10 RNH2 Kb=1.8x10-5 HOAc Ka=1.8x10-5 A buffer with a desired pH is 5.0 would be conveniently prepared by appropriate mixtures of a. NaOAc and HOAc b. HOAc and water c. NaOAc and RNH2 d. HOAc and RNH2 49. a. b. c. d.

Which substance is most soluble in water? C6H6 CaCO3 C2H5OH CO2

50. The solubility of BaCrO4 in water is 2.8 x 10-3 g/L what is the Ksp of the salt? MW of

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BaCrO4 253 g/mol a. 1.2x10-10 b. 2.2x10-5 c. 2.8x10-3 d. 7.8 xl0-6 51. Which is the correct expression for the solubility product constant for Ag2CrO4? a. Ksp = [Ag+]2 [CrO4 2-] b. Ksp = [2Ag+]2 [CrO42-] c. Ksp = [Ag+] [CrO42-] d. Ksp = [Ag+] [CrO42-]2 e. Ksp = [2Ag+] [CrO42-] 52. a. b. c. d.

The correct IUPAC name of N2O3 is nitrogen oxide. nitrogen(II) oxide. nitrous oxide dinitrogen trioxide.

53. In which case is the substance with the given formula followed by its correct name? a. KNO2 — potassium nitrate b. FeCl3 — iron(III) chloride c. FeS — iron(II) sulfite d. Mg3N2 — magnesium nitrite e. HClO — hydrochloric oxide 54. Balance the equation for the following reaction, using no fractional coefficients. ? C +? HNO3 " ? CO2 +? NO2 +? H2O The sum of the coefficients in the balanced equation is a. 5 b. 7 c. 9 d. 12 e. 16 55. Complete and balance the equation for the reaction, where the reactants are in aqueous solution. Use no fractional coefficients. ? Na3PO4 + ? Ba(NO3)2 " ? +

?

The number of moles and formula of the product containing Ba are a. 3NaNO3 b. BaPO4 c. Ba(PO4)2 d. Ba2P3 e. Ba3(PO4)2

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According to the kinetic molecular theory,

56. a.

b. c. d. e.

gaseous molecules are continuously in random motion and collisions are perfectly elastic. the absolute temperature of a gas depends on its molar mass. the pressure exerted on a gas affects the speed of its molecules. gaseous molecules can travel in straight or curved paths. all gaseous molecules are diatomic.

57. The volume of a given mass of gas varies inversely with pressure, provided that the temperature remains constant because a. b. c.

d.

e.

attractive forces between gas molecules are negligible. attractive forces between gas molecules are appreciable. the average kinetic energy of the molecules of a gas is proportional to the absolute temperature. increasing the molecular concentration, at constant temperature, means increasing the number of collisions between molecules and container. collisions between gas molecules are perfectly elastic.

58. The Kelvin temperature of one liter of gas is doubled and its pressure is tripled, volume will then be l

/6 L /3 L 3 /2 L 6L 59. Which gas, present in the same closed system, has the greatest average kinetic energy at a given temperature? a. b. c. d.

a. b. c. d.

2

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60. A sample of neon occupies a volume of 27.3 L at STP. What would be the neon volume at 177 oC and 0.100 atm pressure? a. b. c. d.

177 L 350 L 422 L 450 L

61. Under the same conditions of temperature and pressure, the gas whose molecules possess the highest average speed is a. H2O b. O2 c. F2 d. Ne 62. What is the volume of 2.00 mol of helium gas at 27 oC and 3.00 atm? a. b. c. d.

6.1x10-2L 1.48L 16.4L 44.8 L Real gases are most like ideal gases at

63. a. b. c. d.

high pressure and high temperature. low pressure and low temperature. high pressure and low temperature. low pressure and high temperature.

64. 500 mL of a gaseous compound has a mass of 0.9825 g at 0oC and 760 mmHg. What is the approximate molar mass of the compound? a. 19.7 b. 38.7 c. 44.0 d. 58.9 65. The partial pressures of a gaseous mixture are given in the table. What is the mole percent of hydrogen?

Hydrogen neon carbon dioxide None; the average kinetic energy is the same for each gas. a. b. c. d.

hydrogen carbon dioxide methane ethylene 20.0 25.8 38.8 41.7

Partial Pressures 200 mmHg 150 mmHg 320 mmHg 105 mmHg

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66. It is desired to collect enough oxygen over water at 25 oC and 750 mmHg barometric pressure to be equivalent to 1 L of pure oxygen at 0 oC and 760 mmHg. The vapor pressure of water at 25 oC is 23.5 mm. The volume collected is a. 1 L (298/273)(750/760) b. 1 L (273/298)((750-23.5)/(760-23.5)) c. 1 L (273/298)((750-23.5)/760) d. 1 L (298/273)(760/(750-23.5)) 67. Methane, CH4, diffuses in a given apparatus at the rate of 30 mL/min. At what rate would a gas with a molar mass of 100 diffuse under the same conditions? MW of CH4 = 16 g/mol a. 0.77 mL/min b. 30 mL/min c. 6.7 mL/min d. 75 mL/min e. 12.0 mL/min 68. The Arrhenius equation, k= Ae-E/RT expresses the relationship between the reaction rate constant, k, and the energy of activation, E. The probability that colliding molecules will react a. increases with increasing energy of activation. b. depends only on the empirical constant, A. c. increases with decreasing temperature. d. decreases with increasing energy of activation. 69. The rate law for the reaction A+B"C+D is first order in [A] and second order in [B]. If [A] is halved and [B] is doubled, the rate of the reaction will a. b. c. d.

remain the same be increased by a factor of 2. be increased by a factor of 4. be increased by a factor of 8.

70. The addition of a catalyst in a chemical reaction a. increases the concentration of products at equilibrium. b. increases the fraction of reactant molecules with a given kinetic energy. c. provides an alternate path with a different activation energy. d. lowers the enthalpy change in the overall reaction.

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71. The following mechanism has been proposed for the formation of ethylbenzene: CH3CH2Br + AlBr3 " AlBr4- + CH3CH2 + CH3CH2+ + C6H6 " C6H6CH2CH3+ C6H6CH2CH3+ + AlBr4- "AlBr3 + HBr + C6H5CH2CH3 Which substance serves as the catalyst? a. b. c. d.

AlBr3 CH3CH2+ AlBr4 C6H6CH2CH3 +

72. Which substance has the highest boiling point? a. b. c. d.

CH4 He HF Cl2

73. The table presents data for the reaction: The temperature of the reaction is constant. The initial rate is in arbitrary units. 2H2(g) + 2NO(g) " 2H2O(g) + N2(g) Initial Concentration (mol/L) Exp. [NO] x 10-3 [H2] x 10-3 Initial Rate I 6.0 1.0 18 II 6.0 2.0 36 III 1.0 6.0 3 IV 2.0 6.0 12 What is the rate law for this reaction? a. rate = k1 [H2][NO] b. rate = k1 [H2]2 [NO]2 c. rate = k1 [H2]2 [NO] d. rate = k1 [H2] [NO]2 74. The reaction 2A + 2B " C +D proceeds by this mechanism: 2A !" A2 (equilibrium) A2 + B " X + C (rate determining) X+B"D (rapid) The rate equation for the reaction is a. b. c. d.

rate = k[A] [B] rate = k[A]2 [B]2/[C][D] rate = k[A]2 [B]2[D] rate = k[A]2 [B]

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75. What is the correctly reported mass of water based on this data?

a.

Mass of beaker and water 29.62 g Mass of beaker only 28.3220 g a. b. c. d.

1.3g 1.30g 1.298g 1.2980g

76. When a small single piece of magnesium ribbon is dropped into a test tube half filled with dilute sulfuric acid, the metal soon floats to the surface of the liquid. The best explanation for this is that, (Densities, Mg, 1.79 g/cm3; H2SO4(dilute) 1.2 g/cm3) a. b.

c. d. e.

the metal is less dense than the acid. the metal gets hot and expands and decreases its density markedly as it reacts with the acid the magnesium sulfate formed increases the density of the solution. gas bubbles attached to the metal buoy the metal to the top. convection currents set up in the acid carry the metal to the top.

77. The equilibrium vapor pressure of a few liters of a liquid is dependent on a. b. c. d.

c. d. e.

80. The stronger the intermolecular forces in a substance a. b. c. d.

65.4 92.0 184 238

79. When a hypothetical ionic crystal M+X- is heated, it vaporizes to form separate M+(g) and X-(g) ions. The energy required for this vaporization (the lattice energy) will be greatest when

the higher the boiling point. the lower the boiling point. the higher the vapor pressure. the smaller the deviation from ideal gas behavior.

81. Which group of substances is correctly arranged in order from the highest to the lowest melting point? a. b. c. d.

HF>H2>NaF NaF>H2>HF HF>NaF>H2 NaF>HF>H2

82. The fact that H2O has a dipole moment suggests that the water molecule is

the mass of the liquid. the surface area of the liquid the temperature only the volume of the liquid

78. The edge of a unit cube of an element Y, containing two atoms per unit cube, was found (by X- ray diffraction) to be 3.16 x 10-8 cm. The density of the metal is 19.35 g/cm3. What is the approximate atomic molar mass of Y? a. b. c. d.

b.

the electron affinity of X i...