AP Chem Midterm Review
Pi (π) bonding occurs in each of the following species EXCEPT Responses (A)CO2 (B)C 2 H 4 (C)CN- (D)C 6 H 6 (E)CH4
(E)CH4
The following questions refer to the reactions represented below. (A) H2SeO4(aq) + 2 Cl-(aq) + 2 H+(aq) → H2SeO3(aq) + Cl2(g) + H2O(l) (B) S8(s) + 8 O2(g) → 8 SO2(g) (C) 3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l) (D) Ca2+(aq) + SO42-(aq) → CaSO4(s) (E) PtCl4(s) + 2 Cl-(aq) → PtCl62-(aq) A reaction in which the same reactant undergoes both oxidation and reduction
(C) 3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l)
Has a bond order of 2 Refer to the following diatomic species (A) Li2 (B) B2 (C) N2 (D) O2 (E) F2
(D) O2
Equal masses of He and Ne are placed in a sealed container. What is the partial pressure of He if the total pressure in the container is 6 atm? (A)1 atm (B)2 atm (C)3 atm (D)4 atm (E)5 atm
(E)5 atm
Of the following compounds, which is the most ionic? Responses (A)SiCl4 (B)BrCl (C)PCl3 (D)Cl 2 O (E)CaCl2
(E)CaCl2
Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains only one electron in the highest occupied energy sublevel (A)S (B)Ca (C)Ga (D)Sb (E)Br
C. Ga
The pressure, in atm, exerted by 1.85 mol of an ideal gas placed in a 3.00 L container at 35.0°C is given by which of the following expressions? (A) (1.85)(0.0821)(308)/3.00 atm (B) (1.85)(35.0)/(0.0821)(3.00) atm (C) (3.00)/(1.85)(308)(0.0821) atm (D) (1.85)(8.314)(308)/(3.00) atm (E) (3.00)(1.85)/(0.0821)(35.0) atm
(A) (1.85)(0.0821)(308)/3.00 atm
If 200. mL of 0.60 M MgCl2(aq) is added to 400. mL of distilled water, what is the concentration of Mg2+(aq) in the resulting solution? (Assume volumes are additive). (A)0.20 M (B)0.30 M (C)0.40 M (D)0.60 M (E)1.2 M
(A)0.20 M
The London (dispersion) forces are weakest for which of the following gases under the same conditions of temperature and pressure? Responses (A)H2 (B)O 2 (C)Xe (D)F 2 (E)N2
(A)H2
Which of the following molecules has the shortest bond length? (A)N2 (B)O 2 (C)Cl2 (D)Br 2 (E)I2
(A)N2
Of the following molecules, which has the largest dipole moment? (A)CO (B)CO 2 (C)O2 (D)HF (E)F2
(D)HF
Forms monatomic ions with 2- charge in solutions Responses (A)F (B)S (C)Mg (D)Ar (E)Mn
B. S
The electron-dot structure (Lewis structure) for which of the following molecules would have two unshared pairs of electrons on the central atom? Responses (A)H2S (B)NH 3 (C)CH4 (D)HCN (E)CO2
(A)H2S
Has molecules with a pyramidal shape (A)NH3(g) (B)BH 3 (g) (C)H2(g) (D)H2S(g) (E)HBr(g)
(A)NH3(g)
Approximately what mass of CuSO4 • 5H2O (250 g mol-1) is required to prepare 250 mL of 0.10 M copper(II) sulfate solution? (A)4.0 g (B)6.2 g (C)34 g (D)85 g (E)140 g
(B)6.2 g
Sodium chloride is LEAST soluble in which of the following liquids? (A)H 2 O (B)CCl4 (C)HF (D)CH3OH (E)CH3COOH
(B)CCl4
According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the (A)increasing strength of the bonds (B)decreasing size of the central atom (C)increasing electronegativity of the central atom (D)increasing number of unshared pairs of electrons (E)decreasing repulsion between hydrogen atoms
(D)increasing number of unshared pairs of electrons
Is a strong electrolyte in aqueous solution (A)NH 3 (g) (B)BH3(g) (C)H 2 (g) (D)H 2 S(g) (E)HBr(g)
(E)HBr(g)
When 70. milliliter of 3.0-molar Na2CO3 is added to 30. milliliters of 1.0-molar NaHCO3 the resulting concentration of Na+ is Responses (A)2.0 M (B)2.4 M (C)4.0 M (D)4.5 M (E)7.0 M
(D)4.5 M
The molecule with the largest dipole moment (A) CO2 (B) H20 (C) CH4 (D) C2H4 (E) PH3
B. H2O
The ionization energies for element X are listed in the table above. On the basis of the data, element X is most likely to be First: 580 Second: 1,815 Third: 2,740 Fourth: 11,600 Fifth: 14,800 (A)Na (B)Mg (C)Al (D)Si (E)P
C. Al
A 20.0-milliliter sample of 0.200-molar K2CO3 solution is added to 30.0 milliliters of 0.400-molar Ba(NO3)2 solution. Barium carbonate precipitates. The concentration of barium ion, Ba2+, in solution after reaction is (A)0.150 M (B)0.160 M (C)0.200 M (D)0.240 M (E)0.267 M
(B)0.160 M
Step 1. N2H2O2 ⇄ N2HO2- + H+ (fast equilibrium) Step 2. N2HO2- → N2O + OH- (slow) Step 3. H+ + OH- → H2O (fast) Nitramide, N2H2O2, decomposes slowly in aqueous solution. This decomposition is believed to occur according to the reaction mechanism above. The rate law for the decomposition of nitramide that is consistent with this mechanism is given by which of the following? (A)Rate = k[N2H2O2] (B)Rate = k[N2H2O2] [H+] (C)Rate = k[N2H2O2]/[H+] (D)Rate = k[N2H2O2]/[N2HO2] (E)Rate = k[N2H2O2] [OH-]
(C)Rate = k[N2H2O2]/[H+]
K(s)+ ½ Cl2(g) → KCl(s) ΔH° = -437kJ/molrxn K(s)-> k(g)//v K(g)->k+(g)+e-//w Cl2(g)->2Cl(g)//x Cl(g)+e-->Cl-(g)//y K+(g)+Cl-(g)->KCl(s)//z Cl2(g) + 2e- → 2Cl-(g) Which of the following expressions is equivalent to ΔHo for the reaction represented above? (A)x + y (B)x - y (C)x + 2 y (D)x2−y
(C)x + 2 y
I. HSO4- II. H2O III. SO42- HSO4- + H2O ⇌ H3O+ + SO42- In the equilibrium represented above, the species that act as bases include which of the following? (A)II only (B)III only (C)I and II (D)I and III (E)II and III
(E)II and III
How many carbon atoms are contained in 2.8 g of C2H4 ? (A)1.2 x 10e23 (B)3.0 x 10e23 (C)6.0 x 10e23 (D)1.2 x 10e24 (E)6.0 x 102e4
(A)1.2 x 10e23
Based on the data in the tables above, which of the following statements provides the best prediction for the boiling point of NaCl? Responses (A)NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF. (B)NaCl will have a boiling point between that of NaF and MgO because the covalent character of the bonds in NaCl is intermediate between that of MgO and NaF. (C)NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in NaCl. (D)NaCl will have a higher boiling point than MgO because the energy required to transfer electrons from the anion to the cation is larger in NaCl than in MgO.
(A)NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF.
Equal numbers of moles of He(g), Ar(g), and Ne(g) are placed in a glass vessel at room temperature. If the vessel has a pinhole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused? (A)P He < P Ne < P Ar (B)PHe < PAr < PNe (C)P Ne < P Ar < P He (D)PAr < PHe < PNe (E)PHe = PAr = PNe
(A)P He < P Ne < P Ar
Which of the following gases deviates most from ideal behavior? (A)SO2 (B)Ne (C)CH4 (D)N 2 (E)H2
(A)SO2
The geometry of the SO3 molecule is best described as (A)trigonal planar (B)trigonal pyramidal (C)square pyramidal (D)bent (E)tetrahedral
(A)trigonal planar
Of the following electron configurations of neutral atoms, which represents an atom in an excited state? (A)1s2 2s2 2p5 (B)1 s 2 2 s 2 2 p 5 3 s 2 (C)1s2 2s2 2p6 3s1 (D)1 s 2 2 s 2 2 p 6 3 s 2 3 p 2 (E)1s2 2s2 2p6 3s2 3p5
(B)1 s 2 2 s 2 2 p 5 3 s 2
When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled? (A)The density of the gas (B)The pressure of the gas (C)The average velocity of the gas molecules (D)The number of molecules per cm3 (E)The potential energy of the molecules
(B)The pressure of the gas
A 40.0 mL sample of 0.25 M KOH is added to 60.0 mL of 0.15 M Ba(OH)2. What is the molar concentration of OH-(aq) in the resulting solution? (Assume that the volumes are additive.) (A)0.10 M (B)0.19 M (C)0.28 M (D)0.40 M (E)0.55 M
(C)0.28 M
A 2 L container will hold about 4 g of which of the following gases at 0°C and 1 atm? (A)SO 2 (B)N2 (C)CO2 (D)C4H8 (E)NH3
(C)CO2
Of the following single bonds, which is the LEAST polar? (A)N—H (B)H—F (C)O—F (D)I—F (E)O—H
(C)O—F
The hybridization of the carbon atoms in the molecule represented above can be described as Responses (A)sp (B)sp 2 (C)sp3 (D)dsp 2 (E)d2sp
(C)sp3
A sealed vessel contains 0.200 mol of oxygen gas, 0.100 mol of nitrogen gas, and 0.200 mol of argon gas. The total pressure of the gas mixture is 5.00 atm. The partial pressure of the argon is (A)0.200 atm (B)0.500 atm (C)1.00 atm (D)2.00 atm (E)5.00 atm
(D)2.00 atm
A solution is prepared by adding 16 g of CH3OH (molar mass 32 g) to 90. g of H2O (molar mass 18 g). The mole fraction of CH3OH in this solution is closest to which of the following? (A) .1 (B) .2 (C) .3 (D) .4 (E) .6
A. 0.1
When the actual gas volume is greater than the volume predicted by the ideal gas law, the explanation lies in the fact that the ideal gas law does NOT include a factor for molecular. (A)volume (B)mass (C)velocity (D)attractions (E)shape
(A)volume
N2 molecules absorb ultraviolet light but not visible light. I2 molecules absorb both visible and ultraviolet light. Which of the following statements explains the observations? (A)More energy is required to make N 2 molecules vibrate than is required to make I 2 molecules vibrate. (B)More energy is required to remove an electron from an I2 molecule than is required to remove an electron from a N2 molecule. (C)Visible light does not produce transitions between electronic energy levels in the N 2 molecule but does produce transitions in the I 2 molecule. (D)The molecular mass of I2 is greater than the molecular mass of N2.
(C)Visible light does not produce transitions between electronic energy levels in the N 2 molecule but does produce transitions in the I 2 molecule.
The best explanation for the fact that diamond is extremely hard is that diamond crystals (A)are made up of atoms that are intrinsically hard because of their electronic structures (B)consist of positive and negative ions that are strongly attracted to each other (C)are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms (D)are formed under extreme conditions of temperature and pressure (E)contain orbitals or bands of delocalized electrons that belong not to single atoms but to each crystal as a whole
(C)are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms
he volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution is approximately (A)50.0 mL (B)60.0 mL (C)100. ML (D)110. ML (E)120. mL
(D)110. ML
A sample of CaCO3 (molar mass 100. g) was reported as being 30. percent Ca. Assuming no calcium was present in any impurities, the percent of CaCO3 in the sample is (A)30% (B)40% (C)70% (D)75% (E)100%
(D)75%
In which of the following processes are covalent bonds broken? (A)I 2 ( s ) → I 2 ( g ) (B)CO2(s) → CO2(g) (C)NaCl( s ) → NaCl( l ) (D)C(diamond) → C(g) (E)Fe(s) → Fe(l)
(D)C(diamond) → C(g)
A 0.10 M aqueous solution of sodium sulfate, Na2SO4 , is a better conductor of electricity than a 0.10 M aqueous solution of sodium chloride, NaCl. Which of the following best explains this observation? (A)Na 2 SO 4 is more soluble in water than NaCl is. (B)Na2SO4 has a higher molar mass than NaCl has. (C)To prepare a given volume of 0.10 M solution, the mass of Na 2 SO 4 needed is more than twice the mass of NaCl needed. (D)More moles of ions are present in a given volume of 0.10 M Na2SO4 than in the same volume of 0.10 M NaCl. (E)The degree of dissociation of Na2SO4 in solution is significantly greater than that of NaCl.
(D)More moles of ions are present in a given volume of 0.10 M Na2SO4 than in the same volume of 0.10 M NaCl.
Boiling points of (degrees Celsius) HF: 19 HCl: -85 HBr:-67 HI: -35 The liquefied hydrogen halides have the normal boiling points given above. The relatively high boiling point of HF can be correctly explained by which of the following? (A)HF gas is more ideal. (B)HF is the strongest acid. (C)HF molecules have a smaller dipole moment. (D)HF is much less soluble in water. (E)HF molecules tend to form hydrogen bonds.
(E)HF molecules tend to form hydrogen bonds.
Two flexible containers for gases are at the same temperature and pressure. One holds 0.50 gram of hydrogen and the other holds 8.0 grams of oxygen. Which of the following statements regarding these gas samples is FALSE? (A)The volume of the hydrogen container is the same as the volume of the oxygen container. (B)The number of molecules in the hydrogen container is the same as the number of molecules in the oxygen container. (C)The density of the hydrogen sample is less than that of the oxygen sample. (D)The average kinetic energy of the hydrogen molecules is the same as the average kinetic energy of the oxygen molecules. (E)The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.
(E)The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.
On the basis of strength of intermolecular forces, which of the following elements would be expected to have the highest melting point? (A)Br 2 (B)Cl2 (C)F 2 (D)Kr (E)N2
(A)Br 2
Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigid container. If the temperature of the system remains constant, which of the following statements about the partial pressure of gas X is correct? (A)It is equal to ⅓ the total pressure (B)It depends on the intermolecular forces of attraction between molecules of X, Y, and Z. (C)It depends on the relative molecular masses of X, Y, and Z. (D)It depends on the average distance traveled between molecular collisions. (E)It can be calculated with knowledge only of the volume of the container.
(C)It depends on the relative molecular masses of X, Y, and Z.
The molecule that has trigonal pyramidal geometry A) CO2 (B) H2O (C) CH4 (D) C2H4 (E) PH3
(E) PH3
A flask contains 0.25 mole of SO2(g), 0.50 mole of CH4(g), and 0.50 mole of O2(g). The total pressure of the gases in the flask is 800 mm Hg. What is the partial pressure of the SO2(g) in the flask? (A)800 mm Hg (B)600 mm Hg (C)250 mm Hg (D)200 mm Hg (E)160 mm Hg
(E)160 mm Hg
When hafnium metal is heated in an atmosphere of chlorine gas, the product of the reaction is found to contain 62.2 percent Hf by mass and 37.4 percent Cl by mass. What is the empirical formula for this compound? (A) HfCl (B)HfCl 2 (C)HfCl3 (D)HfCl 4 (E)Hf2Cl3
C. HfCl3
A compound contains 1.10 mol of K, 0.55 mol of Te, and 1.65 mol of O. What is the simplest formula of this compound? Responses (A)KTeO (B)KTe 2 O (C)K2TeO3 (D)K 2 TeO 6 (E)K4TeO6
C. K2TeO3
H - C ≡ C - H What is the hybridization of the carbon atoms in a molecule of ethyne, represented above? Responses (A)sp (B)sp 2 (C)sp3 (D)dsp 2 (E)d2sp
(A)sp
Which of the following molecules contains only single bonds? (A)CH 3 COOH (B)CH3CH2COOCH3 (C)C 2 H 6 (D)C6H6 (E)HCN
(C)C 2 H 6
A compound contains 30. percent sulfur and 70. percent fluorine by mass. The empirical formula of the compound is (A)SF (B)SF 2 (C)SF4 (D)SF 6 (E)S2F
C. SF4
The photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum? Responses (A)Nitrogen atoms have a half-filled p subshell (B)There are more electron-electron repulsions in oxygen atoms than in nitrogen atoms. (C)Electrons in the p subshell of oxygen atoms provide more shielding than electrons in the p subshell of nitrogen atoms. (D)Nitrogen atoms have a smaller nuclear charge than oxygen atoms.
D. Nitrogen has a smaller nuclear charge than oxygen
What number of moles of O2 is needed to produce 14.2 grams of P4O10 from P? (Molecular weight P4O10 = 284) (A) 0.0500 mole (B) 0.0625 mole (C) 0.125 mole (D) 0.250 mole
D.0.250
The elements in which of the following have most nearly the same atomic radius? (A)Be, B, C, N (B)Ne, Ar, Kr, Xe (C)Mg, Ca, Sr, Ba (D)C, P, Se, I (E)Cr, Mn, Fe, Co
E. Cr, Mn, Fe, Co
***1s2 2s2 2p6 3s2 3p3 Atoms of an element, X, have the electronic configuration shown above. The compound most likely formed with magnesium, Mg, is Responses (A)MgX (B)Mg2X (C)MgX2 (D)MgX3 (E)Mg3X2
E.Mg2X3
Of the following organic compounds, which is LEAST soluble in water at 298 K? (A)CH 3 OH, methanol (B)CH3CH2CH2OH, l-propanol (C)C 6 H 14 , hexane (D)C6H12O6, glucose (E)CH3COOH, ethanoic (acetic) acid
(C)C 6 H 14 , hexane
The molecule with only 1 double bond (A) CO2 (B) H20 (C) CH4 (D) C2H4 (E) PH3
(D) C2H4
Which of the following species is NOT planar? (A)CO 3 2- (B)NO3- (C)ClF 3 (D)BF3 (E)PCl3
(E)PCl3
Which of the following properties generally decreases across the periodic table from sodium to chlorine? (A)First ionization energy (B)Atomic mass (C)Electronegativity (D)Maximum value of oxidation number (E)Atomic radius
(E)Atomic radius
Which of the following techniques is most appropriate for the recovery of solid KNO3 from an aqueous solution of KNO3? (A)Paper chromatography (B)Filtration (C)Titration (D)Electrolysis (E)Evaporation to dryness
(E)Evaporation to dryness
In solid methane, the forces between neighboring CH4 molecules are best characterized as (A)ionic bonds (B)covalent bonds (C)hydrogen bonds (D)ion-dipole forces (E)London (dispersion) forces
(E)London (dispersion) forces
Time: 0,1, 2, 3, 4, 5, 6, 7, 10, 20 Reactant (%) left: 100, 79, 63, 50, 40, 31, 25, 20, 10, 1 A reaction was observed for 20 days and the percentage of the reactant remaining after each day was recorded in the table above. Which of the following best describes the order and the half-life of the reaction? (A) Reaction Order: first Half life (Days): 3 (B) Reaction Order: first Half life (Days): 10 (C) Reaction Order: second Half life (Days): 3 (D) Reaction Order: second Half life (Days): 3 (E) Reaction Order: second Half life (Days): 10
(A) Reaction Order: first Half life (Days): 3
3 C2H2(g) → C6H6(g) What is the standard enthalphy change ΔHo, for the reaction represented above? (ΔHof of C2H2(g) is 230 kJ mol-1; (ΔHof of C6H6(g) is 83 kJ mol-1;) (A)-607 kJ (B)-147 kJ (C)-19 kJ (D)+19 kJ (E)+773 kJ
(A)-607 kJ
If 0.40 mol of H2 and 0.15 mol of O2 were to react as completely as possible to produce H2O, what mass of reactant would remain? (A)0.20 g of H 2 (B)0.40 g of H2 (C)3.2 g of O 2 (D)4.0 g of O2 (E)4.4 g of O2
(A)0.20 g of H 2
H3AsO4 + 3 I- + 2 H3O+ → H3AsO3 + I3- + H2O The oxidation of iodide ions by arsenic acid in acidic aqueous solution occurs according to the stoichiometry shown above. The experimental rate law of the reaction is: Rate = k[H3AsO4] [I-] [H3O+] What is the order of the reaction with respect to I-? (A)1 (B)2 (C)3 (D)5 (E)6
(A)1
CS2(l) + 3 O2(g) → CO2(g) + 2 SO2(g) What volume of O2(g) is required to react with excess CS2(l) to produce 4.0 L of CO2(g)? (Assume all gases are measured at 0°C and 1 atm.) (A)12 L (B)22.4 L (C)2 × 22.4 L (D)3 × 22.4 L
(A)12 L
An oxidation-reduction reaction that is also a synthesis reaction (A)2 Mg( s ) + O 2 ( g ) → 2 MgO( s ) (B)Pb2+(aq) + CrO42-(aq) → PbCrO4(s) (C)SO 3 ( g ) + 2 H 2 O( l ) → H 3 O + ( aq ) + HSO 4 - ( aq ) (D)2 H 2 O( g ) → 2 H 2 ( g ) + O 2 ( g ) (E)Ag+(aq) + 2 NH3(aq) → [Ag(NH3)2]+(aq)
(A)2 Mg( s ) + O 2 ( g ) → 2 MgO( s )
NH4NO3(s) → N2O(g) + 2 H2O(g) A 0.03 mol sample of NH4NO3(s) is placed in a 1 L evacuated flask, which is then sealed and heated. The NH4NO3(s) decomposes completely according to the balanced equation above. The total pressure in the flask measured at 400 K is closest to which of the following? (The value of the gas constant, R, is 0.082 L atm mol-1 K-1.) (A)3 atm (B)1 atm (C)0.5 atm (D)0.1 atm (E)0.03 atm
(A)3 atm
2 N2H4(g) + N2O4(g) → 3 N2(g) + 4 H2O(g) When 8.0 g of N2H4 (32 g mol-1) and 92 g of N2O4 (92 g mol-1) are mixed together and react according to the equation above, what is the maximum mass of H2O that can be produced? (A)9.0 g (B)18 g (C)36 g (D)72 g (E)144 g
(A)9.0 g
HC2H3O2(aq) + CN-(aq) ⇄ HCN(aq) + C2H3O2-(aq) The reaction represented above has an equilibrium constant equal to 3.7 x 104. Which of the following can be concluded from this information? (A)CN - ( aq ) is a stronger base than C 2 H 3 O 2 - ( aq ). (B)HCN(aq) is a stronger acid than HC2H3O2(aq). (C)The conjugate base of CN - ( aq ) is C 2 H 3 O 2 - ( aq ). (D)The equilibrium constant will increase with an increase in temperature. (E)The pH of a solution containing equimolar amounts of CN-(aq) and HC2H3O2 (aq) is 7.0.
(A)CN - ( aq ) is a stronger base than C 2 H 3 O 2 - ( aq ).
A 0.50g sample of Mg(s) was placed in a solution of HCl(aq), where it reacted completely. Which of the following equations best represents the reacting species in the reaction described above? (A)Mg(s)+2H+(aq)→Mg2+(aq)+H2(g) (B)Mg(s)+HCl(aq)→MgCl2(aq)+H2(g) (C)Mg(s)+2HCl(aq)→MgCl2(s)+2H+(aq) (D)Mg(s)+2HCl(aq)→Mg2+(aq)+Cl2(g)+H2(g)
(A)Mg(s)+2H+(aq)→Mg2+(aq)+H2(g)
2NO(g) + O2(g)→N2O2(g) A possible mechanism for the overall reaction represented above is the following. NO(g) + NO(g) → N2O2(g) slow N2O2(g) + O2(g) → 2NO2(g) fast Which of the following rate expressions agrees best with this possible mechanism? (A)Rate = k[NO] 2 (B)Rate = k[NO]/[O2] (C)Rate = k[NO]2/[O2] (D)Rate = k[NO] 2 [O 2 ] (E)Rate = k[N2O2] [O2]
(A)Rate = k[NO] 2?
The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase? (A)The London (dispersion) forces increase. (B)The hydrogen bonding increases. (C)The dipole-dipole forces increase. (D)The chemical reactivity increases. (E)The number of nearest neighbors increases.
(A)The London (dispersion) forces increase.
At standard temperature and pressure, a 0.50 mol sample of H2 gas and a separate 1.0 mol sample of O2 gas have the same (A)average molecular kinetic energy (B)average molecular speed (C)volume (D)effusion rate (E)density
(A)average molecular kinetic energy
2 SO2(g) + O2(g) → 2 SO3(g) A mixture of gases containing 0.20 mol of SO2 and 0.20 mol of O2 in a 4.0 L flask reacts to form SO3. If the temperature is 25ºC, what is the pressure in the flask after reaction is complete? (A) 0.4(0.082)(298)/4 atm (B) 0.3(0.082)(298)/4 atm (C) 0.2(0.082)(298)/4 atm (D) 0.2(0.082)(25)/4 atm (E) 0.3(0.082)(25)/4 atm
(B) 0.3(0.082)(298)/4 atm
Initial NO (mol/L), Initial O2(mol/L), Initial rate of formation of NO2(mol/Lsec) Experiment 1: 0.10, 0.10, 2.5x10^-4 Experiment 2: 0.20, 0.10, 5.0x10^-4 Experiment 3: 0.20, 0.40, 8.0x10^-3 The initial-rate data in the table above were obtained for the reaction represented below. What is the experimental rate law for the reaction? 2 NO(g) + O2(g) → NO2(g) (A) Rate = k [NO][O 2 ] (B) Rate = k[NO][O2]2 (C) Rate = k [NO] 2 [O 2 ] (D) Rate = k[NO]2[O2]2 (E) Rate = k[NO] / [O2]
(B) Rate = k[NO][O2]2
A 100g sample of a metal was heated to 100oC and then quickly transferred to an insulated container holding 100g of water at 22oC. The temperature of the water rose to reach a final temperature of 35oC. Which of the following can be concluded? (A) The metal temperature changed more than the water temperature did; therefore the metal lost more thermal energy than the water gained. (B) The metal temperature changed more than the water temperature did, but the metal lost the same amount of thermal energy as the water gained. (C) The metal temperature changed more than the water temperature did; therefore the heat capacity of the metal must be greater than the heat capacity of the water. (D) The final temperature is less than the average starting temperature of the metal and the water; therefore the total energy of the metal and water decreased.
(B) The metal temperature changed more than the water temperature did, but the metal lost the same amount of thermal energy as the water gained.
he pH of a solution prepared by the addition of 10. mL of 0.002 M KOH(aq) to 10. mL of distilled water is closest to (A)12 (B)11 (C)10 (D)4 (E)3
(B)11
What mass of Au is produced when 0.0500 mol of Au2S3 is reduced completely with excess H2? (A) 9.85 g (B)19.7 g (C)24.5 g (D)39.4 g (E)48.9 g
(B)19.7 g
Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 mL sample of a solution? (A)5 mL pipet (B)25 mL pipet (C)25 mL beaker (D)25 mL Erlenmeyer flask (E)50 mL graduated cylinder
(B)25 mL pipet
A student wishes to prepare 2.00 liters of 0.100-molar KIO3 (molecular weight 214). The proper procedure is to weigh out (A)42.8 grams of KIO 3 and add 2.00 kilograms of H 2 O (B)42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters (C)21.4 grams of KIO 3 and add H 2 O until the final homogeneous solution has a volume of 2.00 liters (D)42.8 grams of KIO3 and add 2.00 liters of H2O (E)21.4 grams of KIO3 and add 2.00 liters of H2O
(B)42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters
The isomerization of cyclopropane to propylene is a first-order process with a half-life of 19 minutes at 500oC. The time it takes for the partial pressure of cyclopropane to decrease from 1.0 atmosphere to 0.125 atmosphere at 500oC is closest to (A)38 minutes (B)57 minutes (C)76 minutes (D)152 minutes (E)190 minutes
(B)57 minutes
The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following? I. Mg2+ is more positively charged than Na+. II. O2- is more negatively charged than F-. III. The O2- ion is smaller than the F- ion. (A)II only (B)I and II only (C)I and III only (D)II and III only (E)I, II, and III
(B)I and II only
On the basis of the solubility curves shown above, the greatest percentage of which compound can be recovered by cooling a saturated solution of that compound from 90°C to 30°C? (A)NaCl (B)KNO3 (C)K 2 CrO 4 (D)K2SO4 (E)Ce2(SO4)3
(B)KNO3
Which of the following is the conjugate acid of NH2- ? (A)NH2- (B)NH 3 (C)H+ (D)NH 4 + (E)H2O
(B)NH 3
Experiment 1: Initial X: 0.1 Initial Y: 0.3 Initial rate of formation: 4.0x10^-4 Experiment 2: Initial X: 0.2 Initial Y: 0.6 Initial rate of formation: 1.6x10^-3 Experiment 3: Initial X: 0.2 Initial Y: 0.3 Initial rate of formation: 4.0x10^-4 The data in the table above were obtained for the reaction X + Y → Z. Which of the following is the rate law for the reaction? (A)Rate = k [X] 2 (B)Rate = k[Y]2 (C)Rate = k [X][Y] (D)Rate = k[X]2[Y] (E)Rate = k[X][Y]2
(B)Rate = k[Y]2
For which of the following molecules are resonance structures necessary to describe the bonding satisfactorily? Responses (A)H2S (B)SO 2 (C)CO2 (D)OF 2 (E)PF3
(B)SO 2
2N2O5(g) → 4NO2(g) + O2(g) A sample of N2O5 was placed in an evacuated container, and the reaction represented above occurred. The value of PN2O52O5(g), was measured during the reaction and recorded in the table below. Which of the following correctly describes the reaction? (A)The decomposition of N 2 O 5 is a zero-order reaction. (B)The decomposition of N2O5 is a first-order reaction. (C)The decomposition of N 2 O 5 is a second-order reaction. (D)The overall reaction order is 3.
(B)The decomposition of N2O5 is a first-order reaction.
A 0.50g sample of Mg(s) was placed in a solution of HCl(aq), where it reacted completely. In a third experiment, 0.10g samples of Mg(s) are placed in excess HCl(aq) of various concentrations: 0.050M, 0.10M, 0.25M, and 0.50M. The reactions are run in successive order from 0.050M to 0.50M, and the time required for each reaction to go to completion is recorded. As the concentration of HCl(aq) increases from 0.050M to 0.50M, which of the following is the expected result? (A)The reaction time increases, and the rate of the reaction decreases. (B)The reaction time decreases, and the rate of the reaction increases. (C)Both the reaction time and the rate of the reaction increase. (D)Both the reaction time and the rate of the reaction decrease.
(B)The reaction time decreases, and the rate of the reaction increases.
Container A: Methane, CH4, 16 g/mol, 27 degrees Celsius, 2.0 atm Container B: Ethane, C2H6, 30 g/mol 27 degrees Celsius, 4.0atm Container C: Butane, C4H10, 58 g/mol, 27 degrees Celsius, 2.0atm he density of the gas, in g/L, is (A)greatest in container A (B)greatest in container B (C)greatest in container C (D)the same in all three containers
(B)greatest in container B
The following questions relate to the graph below. The graph shows the temperature of a pure substance as it is heated at a constant rate in an open vessel at 1.0 atm pressure. The substance changes from the solid to the liquid to the gas phase. The substance is at its normal freezing point at time (A)t 1 (A on diagram) (B)t2 (B on diagram) (C)t 3 (C on diagram) (D)t4 (D on diagram) (E)t5 (D on diagram)
(B)t2
Which of the values of ∆Ho for a process in the table is (are) less than zero (i.e., indicate(s) an exothermic process)? (A)z only (B)y and z only (C)x , y , and z only (D)w, x, y, and z
(B)y and z only
Contains 1 sigma (σ) and 2 pi (π) bonds Refer to the following diatomic species (A) Li2 (B) B2 (C) N2 (D) O2 (E) F2
(C) N2
Has the largest bond-dissociation energy Refer to the following diatomic species (A) Li2 (B) B2 (C) N2 (D) O2 (E) F2
(C) N2
Under which of the following conditions of temperature and pressure would 1.0 mol of the real gas CO2(g) behave most like an ideal gas? (A) Temperature(K): 100. Pressure(atm): 0.1 (B) Temperature(K): 100. Pressure(atm): 100 (C) Temperature(K): 800 Pressure(atm): 0.1 (D) Temperature(K): 800 Pressure(atm): 1 (E) Temperature(K): 800 Pressure(atm): 100
(C) Temperature(K): 800 Pressure(atm): 0.1
. . . C10H12O4S(s) + . . . O2(g) → . . . CO2(g) + . . . SO2(g) + . . . H2O(g) When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2(g) is (A)6 (B)7 (C)12 (D)14 (E)28
(C)12
A Lewis diagram for the molecule C2H4C2H4 is shown above. In the actual C2H4C2H4 molecule, the H-C-HH-C-H bond angles are closest to (A)90 degrees (B)109.5 degrees (C)120 degrees (D)180 degrees
(C)120 degrees
2 KClO3 (s)−→−−MnO2Δ2 KCl (s)+3 O2 (g) According to the equation above, how many moles of potassium chlorate, KClO3 , must be decomposed to generate 1.0 L of O2 gas at standard temperature and pressure? (A)1/3(122.4) (B)1/2(122.4) (C)2/3(122.4) (D)3/2(122.4) (E)2(122.4)
(C)2/3(122.4)
Container A: Methane, CH4, 16 g/mol, 27 degrees Celsius, 2.0 atm Container B: Ethane, C2H6, 30 g/mol 27 degrees Celsius, 4.0atm Container C: Butane, C4H10, 58 g/mol, 27 degrees Celsius, 2.0atm If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure? (A)Methane (B)Ethane (C)Butane (D)All the gases will condense at the same pressure.
(C)Butane
To make Au stronger and harder, it is often alloyed with other metals, such as Cu and Ag. Consider two alloys, one of Au and Cu and one of Au and Ag, each with the same mole fraction of Au. If the Au/Cu alloy is harder than the Au/Ag alloy, then which of the following is the best explanation based on the information in the table above? Responses (A)Cu has two common oxidation states, but Ag has only one. (B)Cu has a higher melting point than Au has, but Ag has a lower melting point than Au has. (C)Cu atoms are smaller than Ag atoms, thus they interfere more with the displacement of atoms in the alloy. (D)Cu atoms are less polarizable than are Au or Ag atoms, thus Cu has weaker interparticle forces.
(C)Cu atoms are smaller than Ag atoms, thus they interfere more with the displacement of atoms in the alloy.
I. The average molecular mass of the gas II. The average distance between the molecules III. The average speed of the molecules A sample of an ideal gas is cooled from 50.0oC to 25.0oC in a sealed container of constant volume. Which of the following values for the gas will decrease? (A)I only (B)II only (C)III only (D)I and III (E)II and III
(C)III only
Image: Dye starts at the bottom of the chromatography paper, then it shows the solvent front at the top and near it is the dye. Based on the results of the paper chromatography experiment shown above, which of the following can be concluded about the dye? (A)It has a small molar mass. (B)It has weak intermolecular forces. (C)It has a weaker attraction for the stationary phase that it has for the mobile phase. (D)It has a stronger attraction for the stationary phase than it has for the mobile phase.
(C)It has a weaker attraction for the stationary phase that it has for the mobile phase.
A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature? (A)The volume of the gas increases. (B)The pressure of the gas decreases. (C)The average speed of the gas molecules remains the same. (D)The total number of gas molecules remains the same. (E)The average distance between the gas molecules increases.
(C)The average speed of the gas molecules remains the same.
Nonane and 2,3,4-trifluoropentane have almost identical molar masses, but nonane has a significantly higher boiling point. Which of the following statements best helps explain this observation? (A)The C-F is easier to break than the C-H bond. (B)The C-F is more polar than the C-H bond. (C)The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane. (D)The carbon chains are farther apart in a sample of nonane than they are in 2,3,4-trifluoropentane.
(C)The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane.
The following questions refer to the reactions represented below. (A) H2SeO4(aq) + 2 Cl-(aq) + 2 H+(aq) → H2SeO3(aq) + Cl2(g) + H2O(l) (B) S8(s) + 8 O2(g) → 8 SO2(g) (C) 3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l) (D) Ca2+(aq) + SO42-(aq) → CaSO4(s) (E) PtCl4(s) + 2 Cl-(aq) → PtCl62-(aq) A precipitation reaction
(D) Ca2+(aq) + SO42-(aq) → CaSO4(s)
Container A: Methane, CH4, 16 g/mol, 27 degrees Celsius, 2.0 atm Container B: Ethane, C2H6, 30 g/mol 27 degrees Celsius, 4.0atm Container C: Butane, C4H10, 58 g/mol, 27 degrees Celsius, 2.0atm The average kinetic energy of the gas molecules is (A) greatest in container A (B) greatest in container B (C) greatest in container C (D) the same in all three containers
(D) the same in all three containers
A 360. mg sample of aspirin, C9H8O4, (molar mass 180. g), is dissolved in enough water to produce 200. mL of solution. What is the molarity of aspirin in a 50. mL sample of this solution? (A)0.0800 M (B)0.0400 M (C)0.0200 M (D)0.0100 M (E)0.00250 M
(D)0.0100 M
HCl(aq)+CaCO3(s)→CaCl2(aq)+CO2(g)+H2O(l) The reaction between HCl(aq) and CaCO3(s) is represented by the equation above. Two separate trials were carried out using CaCO3(s) samples of the same mass, but one sample was a single piece of CaCO3(s), and one sample was composed of small pieces of CaCO3(s). The loss of mass of CaCO3(s) as a function of time for both trials is shown in the graph below. Which of the curves, X or Y, represents the reaction with small pieces of CaCO3(s), and why? (A)Curve X , because it shows that the reaction proceeded at a uniform rate. (B)Curve X, because it takes a shorter time for the reaction to go to completion due to the larger surface area of CaCO3(s). (C)Curve Y , because it shows that the reaction proceeded at a nonuniform rate. (D)Curve Y, because it takes a shorter time for the reaction to go to completion due to the larger surface area of CaCO3(s).
(D)Curve Y, because it takes a shorter time for the reaction to go to completion due to the larger surface area of CaCO3(s).
A kinetics experiment is set up to collect the gas that is generated when a sample of chalk, consisting primarily of solid CaCO3, is added to a solution of ethanoic acid, CH3COOH. The rate of reaction between CaCO3 and CH3COOH is determined by measuring the volume of gas generated at 22oC and 1 atm as a function of time. Which of the following experimental conditions is most likely to increase the rate of gas production? (A)Decreasing the volume of ethanoic acid solution used in the experiment (B)Decreasing the concentration of the ethanoic acid solution used in the experiment (C)Decreasing the temperature at which the experiment is performed (D)Decreasing the particle size of the CaCO3 by grinding it into a fine powder
(D)Decreasing the particle size of the CaCO3 by grinding it into a fine powder
2 MnO4-(aq) + 10 Br-(aq) + 16 H+(aq) → 2 Mn2+(aq) + 5 Br2(aq) + 8 H2O(l) How many electrons are transferred in the reaction represented by the balanced equation above? (A)2 (B)4 (C)5 (D)8 (E)10
(E)10
I. Frequency of collisions of reactant particles II. Kinetic energy of collisions of reactant particles III. Orientation of reactant particles during collisions Factors that affect the rate of a chemical reaction include which of the following? (A)II only (B)I and II only (C)I and III only (D)II and III only (E)I, II, and III
(E)I, II, and III
Which of the following has a zero dipole moment? Responses (A)HCN (B)NH 3 (C)SO2 (D)NO 2 (E)PF5
(E)PF5
In which of the following species does sulfur have the same oxidation number as it does in H2SO4? Responses (A)H2SO3 (B)S 2 O 3 2- (C)S2- (D)S 8 (E)SO2Cl2
(E)SO2Cl2
X: CH3—CH2—CH2—CH2—CH3 Y: CH3—CH2—CH2—CH2—OH Z: HO—CH2—CH2—CH2—OH Based on concepts of polarity and hydrogen bonding, which of the following sequences correctly lists the compounds above in the order of their increasing solubility in water? (A)Z < Y < X (B)Y < Z < X (C)Y < X < Z (D)X < Z < Y (E)X < Y < Z
(E)X < Y < Z
The figure above shows two closed containers. Each contains the same volume of acetone in equilibrium with its vapor at the same temperature. The vapor pressure of the acetone is (A)higher in container 1 because the surface area of the liquid is greater (B)higher in container 1 because the volume of vapor is greater (C)lower in container 1 because the level of the liquid is lower (D)the same in both containers because the volume of the liquid is the same (E)the same in both containers because the temperature is the same
(E)the same in both containers because the temperature is the same
Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains exactly two unpaired electrons Responses (A)S (B)Ca (C)Ga (D)Sb (E)Br
A. S
Which of the following shows the correct number of protons, neutrons, and electrons in a neutral cesium-134 atom? A. 55, 55, 55 B. 55, 79, 55 C. 55, 79, 79 D. 79, 55, 79 E. 134, 55, 134
B. Protons: 55/Neutrons:79/Electrons: 55
How many mL of 10.0 M HCl are needed to prepare 500. mL of 2.00 M HCl ? (A)1.00 mL (B)10.0 mL (C)20.0 mL (D)100. mL (E)200. mL
(D)100. mL
Which of the following best helps to account for the fact that the F- ion is smaller than the O2- ion? (A)F- has a larger nuclear mass than O2- has. (B)F - has a larger nuclear charge than O 2- has. (C)F- has more electrons than O2- has. (D)F - is more electronegative than O 2- is. (E)F- is more polarizable than O2- is.
B. F- has a larger nuclear charge than O2- has.
The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best accounts for which of the following? (A)Na has a greater density at standard conditions than Ne. (B)Na has a lower first ionization energy than Ne. (C)Na has a higher melting point than Ne. (D)Na has a higher neutron-to-proton ratio than Ne. (E)Na has fewer naturally occurring isotopes than Ne.
B. Na has a lower first ionization energy than Ne
After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of 38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference? (A)Strong initial heating caused some of the hydrate sample to spatter out of the crucible. (B)The dehydrated sample absorbed moisture after heating. (C)The amount of the hydrate sample used was too small. (D)The crucible was not heated to constant mass before use. (E)Excess heating caused the dehydrated sample to decompose.
B. The dehydrated sample absorbed moisture after heating.
Which of the following molecules has an angular (bent) geometry that is commonly represented as a resonance hybrid of two or more electron-dot structures? A. CO 2 B. O3 C. CH4 D. BeF2 E. OF2
(B) O3
A precipitation reaction (A)2 Mg( s ) + O 2 ( g ) → 2 MgO( s ) (B)Pb2+(aq) + CrO42-(aq) → PbCrO4(s) (C)SO 3 ( g ) + 2 H 2 O( l ) → H 3 O + ( aq ) + HSO 4 - ( aq ) (D)2 H 2 O( g ) → 2 H 2 ( g ) + O 2 ( g ) (E)Ag+(aq) + 2 NH3(aq) → [Ag(NH3)2]+(aq)
(B)Pb2+(aq) + CrO42-(aq) → PbCrO4(s)
Solid ethyl alcohol, C2H5OH is (A)A network solid with covalent bonding (B)A molecular solid with zero dipole moment (C)A molecular solid with hydrogen bonding (D)An ionic solid (E)A metallic solid
(C)A molecular solid with hydrogen bonding
Which of the following is a nonpolar molecule that contains polar bonds? Responses (A)F2 (B)CHF 3 (C)CO2 (D)HCl (E)NH3
(C)CO2
1s22s22p63s23p6 Which of the following species has the electron configuration shown above? (A)O (B)Ne (C)K+ (D)Cl+
(C)K+
At constant temperature, the behavior of a sample of a real gas more closely approximates that of an ideal gas as its volume is increased because the (A) collisions with the walls of the container become less frequent (B) average molecular speed decreases (C) molecules have expanded (D) average distance between molecules becomes greater (E) average molecular kinetic energy decreases
(D) average distance between molecules becomes greater
In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00? (A)CrO3 (B)CrO 2 (C)CrO (D)Cr 2 O (E)Cr2O3
B. CrO2
2 H2O(l) + 4 MnO4-(aq) + 3 ClO2-(aq) → 4 MnO2(s) + 3 ClO4-(aq) + 4 OH-(aq) According to the balanced equation above, how many moles of ClO2-(aq) are needed to react completely with 20. mL of 0.20 M KMnO4 solution? (A)0.0030 mol (B)0.0053 mol (C)0.0075 mol (D)0.013 mol (E)0.030 mol
(A)0.0030 mol
3 Ag(s) + 4 HNO3 → 3 AgNO3 + NO(g) + 2 H2O The reaction of silver metal and dilute nitric acid proceeds according to the equation above. If 0.10 mole of powdered silver is added to 10. milliliters of 6.0-molar nitric acid, the number of moles of NO gas that can be formed is (A)0.015 mole (B)0.020 mole (C)0.030 mole (D)0.045 (E)0.090
(A)0.015 mole
Initial buret reading 2.17mL Final buret reading 22.17mL An antacid tablet containing Mg(OH)2(s) (molar mass 58.3g/mol) is titrated with a 0.100M solution of HNO3(aq). The end point is determined by using an indicator. Based on the data in the table above, what was the mass of the Mg(OH)2(s) in the antacid tablet? (A)0.0583 grams (B)0.583 grams (C)5.83 grams (D)58.3 grams
(A)0.0583 grams
W(g) + X(g) → Y(g) + Z(g) Gases W and X react in a closed, rigid vessel to form gases Y and Z according to the equation above. The initial pressure of W(g) is 1.20 atm and that of X(g) is 1.60 atm. No Y(g) or Z(g) is initially present. The experiment is carried out at constant temperature. What is the partial pressure of Z(g) when the partial pressure of W(g) has decreased to 1.0 atm? (A)0.20 atm (B)0.40 atm (C)1.0 atm (D)1.2 atm (E)1.4 atm
(A)0.20 atm
Which of the following best describes what happens to the substance between t4 and t5? (A)The molecules are leaving the liquid phase. (B)The solid and liquid phases coexist in equilibrium. (C)The vapor pressure of the substance is decreasing. (D)The average intermolecular distance is decreasing. (E)The temperature of the substance is increasing.
(A)The molecules are leaving the liquid phase.
H3AsO4 + 3 I- + 2 H3O+ → H3AsO3 + I3- + H2O The oxidation of iodide ions by arsenic acid in acidic aqueous solution occurs according to the stoichiometry shown above. The experimental rate law of the reaction is: Rate = k[H3AsO4] [I-] [H3O+] According to the rate law for the reaction, an increase in the concentration of hydronium ion has what effect on this reaction? (A)The rate of reaction increases. (B)The rate of reaction decreases. (C)The value of the equilibrium constant increases. (D)The value of the equilibrium constant decreases. (E)Neither the rate nor the value of the equilibrium constant is changed.
(A)The rate of reaction increases.
When 100 mL of 1.0 M Na3PO4 is mixed with 100 mL of 1.0 M AgNO3, a yellow precipitate forms and [Ag+] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration? (A)[PO 4 3- ] < [NO 3 - ] < [Na + ] (B)[PO43-] < [Na+] < [NO3-] (C)[NO 3 - ] < [PO 4 3- ] < [Na + ] (D)[Na+] < [NO3-] < [PO43-] (E)[Na+] < [PO43-] < [NO3-]
(A)[PO 4 3- ] < [NO 3 - ] < [Na + ]
A → X The enthalpy change for the reaction represented above is ΔHT. This reaction can be broken down into a series of steps as shown in the diagram: A relationship that must exist among the various enthalpy changes is Responses (A)ΔHT - ΔH1 - ΔH2 - ΔH3 = 0 (B)Δ H T + Δ H 1 + Δ H 2 + Δ H 3 = 0 (C)ΔH3 - (ΔH1 + ΔH2) = ΔHT (D)Δ H 2 - (Δ H 3 + Δ H 1 ) = Δ H T (E)ΔHT + ΔH2 = ΔH1 + ΔH3
(A)ΔHT - ΔH1 - ΔH2 - ΔH3 = 0
The half-life of 55Cr is about 2.0 hours. The delivery of a sample of this isotope from the reactor to a certain laboratory requires 12 hours. About what mass of such material should be shipped in order that 1.0 mg of 55Cr is delivered to the laboratory? (A)130 mg (B)64 mg (C)32 mg (D)11 mg (E)1.0 mg
(B)64 mg
If 87.5 percent of a sample of pure 131I decays in 24 days, what is the half-life of 131I? (A)6 days (B)8 days (C)12 days (D)14 days (E)21 days
(B)8 days
Step 1: Ce4+ + Mn2+ → Ce3+ + Mn3+ Step 2: Ce4+ + Mn3+ → Ce3+ + Mn4+ Step 3: Mn4+ + Tl+ → Tl3+ + Mn2+ The proposed steps for a catalyzed reaction between Ce4+ and Tl+ are represented above. The products of the overall catalyzed reaction are (A)Ce 4+ and Tl + (B)Ce3+ and Tl3+ (C)Ce 3+ and Mn 3+ (D)Ce3+ and Mn4+ (E)Tl3+ and Mn2+
(B)Ce3+ and Tl3+
Which of the following describes the changes in forces of attraction that occur as H2O changes phase from a liquid to a vapor? (A)H - O bonds break as H - H and O - O bonds form. (B)Hydrogen bonds between H2O molecules are broken. (C)Covalent bonds between H 2 O molecules are broken. (D)Ionic bonds between H+ ions and OH- ions are broken. (E)Covalent bonds between H+ ions and H2O molecules become more effective.
(B)Hydrogen bonds between H2O molecules are broken.
The graph above shows the results of a study of the reaction of X with a large excess of Y to yield Z. The concentrations of X and Y were measured over a period of time. According to the results, which of the following can be concluded about the rate law for the reaction under the conditions studied? (A)It is zero order in [ X ]. (B)It is first order in [X]. (C)It is second order in [ X ]. (D)It is first order in [Y]. (E)The overall order of the reaction is 2.
(B)It is first order in [X].
2 A(g) + B(g) → 2 C(g) When the concentration of substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is that (A) the order of the reaction with respect to substance B is 1 (B)substance B is not involved in any of the steps in the mechanism of the reaction (C) substance B is not involved in the rate-determined step of the mechanism, but is involved in subsequent steps (D) substance B is probably a catalyst, and as such, its effect on the rate of the reaction does not depend on its concentration (E) the reactant with the smallest coefficient in the balanced equation generally has little or no effect on the rate of the reaction
(C) substance B is not involved in the rate-determined step of the mechanism, but is involved in subsequent steps
A 1.0 L sample of an aqueous solution contains 0.10 mol of NaCl and 0.10 mol of CaCl2. What is the minimum number of moles of AgNO3 that must be added to the solution in order to precipitate all of the Cl- as AgCl(s) ? (Assume that AgCl is insoluble.) (A) 0.10 mol (B)0.20 mol (C)0.30 mol (D)0.40 mol (E)0.60 mol
(C)0.30 mol
Gaseous cyclobutene undergoes a first-order reaction to form gaseous butadiene. At a particular temperature, the partial pressure of cyclobutene in the reaction vessel drops to one-eighth its original value in 124 seconds. What is the half-life for this reaction at this temperature? (A)15.5 sec (B)31.0 sec (C)41.3 sec (D)62.0 sec (E)124 sec
(C)41.3 sec
How much heat is released or absorbed when 0.050 mol of Cl2(g) is formed from KCl(s)? (A)87.4 kJ is released (B)43.7 kJ is released (C)43.7 kJ is absorbed (D)87.4 kJ is absorbed
(C)43.7 kJ is absorbed
A 0.50g sample of Mg(s) was placed in a solution of HCl(aq), where it reacted completely. In another experiment, a small piece of Mg(s) is weighed, then placed in a flask containing excess 1MHCl(aq). The student wants to determine number of moles of gas produced. Which of the following is the best way to conduct the experiment for accurate data collection? (A)Conducting the experiment at different temperatures to see which generates the most gas (B)Completing the entire reaction in a large Erlenmeyer flask of known volume to measure the volume of the gas collected (C)Collecting the gas in a eudiometer tube and measuring the volume of the gas collected (D)Conducting the reaction in a graduated cylinder and measuring the volume of the gas collected
(C)Collecting the gas in a eudiometer tube and measuring the volume of the gas collected
K(s)+ ½ Cl2(g) → KCl(s) ΔH° = -437kJ/molrxn K(s)-> k(g)//v K(g)->k+(g)+e-//w Cl2(g)->2Cl(g)//x Cl(g)+e-->Cl-(g)//y K+(g)+Cl-(g)->KCl(s)//z What remains in the reaction vessel after equal masses of K(s) and Cl2(g) have reacted until either one or both of the reactants have been completely consumed? (A)KCl only (B)KCl and K only (C)KCl and Cl 2 only (D)KCl, K, and Cl2
(C)KCl and Cl 2 only
Which of the following ions has the same number of electrons as Br - ? (A)Ca2+ (B)K + (C)Sr2+ (D)I - (E)Cl-
(C)Sr2+
The energy diagram for the reaction X + Y → Z is shown above. The addition of a catalyst to this reaction would cause a change in which of the indicated energy differences? (A)I only (B)II only (C)III only (D)I and II only (E)I, II, and III
(D)I and II only
Which of the following best describes the role of the spark from the spark plug in an automobile engine? (A)The spark decreases the energy of activation for the slow step. (B)The spark increases the concentration of the volatile reactant. (C)The spark supplies some of the energy of activation for the combustion reaction. (D)The spark provides a more favorable activated complex for the combustion reaction. (E)The spark provides the heat of vaporization for the volatile hydrocarbon.
(C)The spark supplies some of the energy of activation for the combustion reaction.
Experiment 1: [X]0: 0.40 [Y]0: 0.10 Initial rate of formation of Z (mol/Lsec): R Experiment 2: [X]0: 0.2 [Y]0: 0.2 Initial rate of formation of Z (mol/Lsec): ? The table above shows the results from a rate study of the reaction X + Y → Z. Starting with known concentrations of X and Y in experiment 1, the rate of formation of Z was measured. If the reaction was first order with respect to X and second order with respect to Y, the initial rate of formation of Z in experiment 2 would be (A)R/4 (B)R/2 (C)R (D)2R (E)4R
(D)2R
. . . Ca3(PO4)2(s) + . . . H3PO4(l) → . . . Ca(H2PO4)2(s) When the equation above is balanced and all coefficients are reduced to lowest whole-number terms, what is the coefficient for H3PO4(l) ? (A)1 (B)2 (C)3 (D)4 (E)5
(D)4
10 HI + 2 KMnO4 + 3 H2SO4 → 5 I2 + 2 MnSO4 + K2SO4 + 8 H2O According to the balanced equation above, how many moles of HI would be necessary to produce 2.5 mol of I2, starting with 4.0 mol of KMnO4 and 3.0 mol of H2SO4 ? (A)20. (B)10. (C)8.0 (D)5.0 (E)2.5
(D)5.0
Rate = k[M][N]2 The rate of a certain chemical reaction between substances M and N obeys the rate law above. The reaction is first studied with [M] and [N] each 1 x 10-3 molar. If a new experiment is conducted with [M] and [N] each 2 x 10-3 molar, the reaction rate will increase by a factor of (A)2 (B)4 (C)6 (D)8 (E)16
(D)8
Which of the following represents a pair of isotopes? Atomic Number | Mass Number Responses (A)I. 6 | 14, II. 7 | 14 (B)I. 6 | 7, II. 14 | 14 (C)I. 6 | 14, II. 14 | 28 (D)I. 7 | 13, II. 7 | 14 (E)|. 8 | 10, ||. 16 | 20
(D)I. 7 | 13, II. 7 | 14
Which of the following represents a process in which a species is reduced? (A)Ca( s ) → Ca 2+ ( aq ) (B)Hg(l) → Hg22+(aq) (C)Fe 2+ ( aq ) → Fe 3+ ( aq ) (D)NO3-(aq) → NO(g) (E)SO32-(aq) → SO42-(aq)
(D)NO3-(aq) → NO(g)
Relatively slow rates of chemical reaction are associated with which of the following? (A)The presence of a catalyst (B)High temperature (C)High concentration of reactants (D)Strong bonds in reactant molecules (E)Low activation energy
(D)Strong bonds in reactant molecules
H2Se(g) + 4 O2F2(g) → SeF6(g) + 2 HF(g) + 4 O2(g) Which of the following is true regarding the reaction represented above? (A)The oxidation number of O does not change. (B)The oxidation number of H changes from -1 to +1. (C)The oxidation number of F changes from +1 to -1. (D)The oxidation number of Se changes from -2 to +6. (E)It is a disproportionation reaction for F.
(D)The oxidation number of Se changes from -2 to +6.
A student pipetted five 25.00-milliliter samples of hydrochloric acid and transferred each sample to an Erlenmeyer flask, diluted it with distilled water, and added a few drops of phenolphthalein to each. Each sample was then titrated with a sodium hydroxide solution to the appearance of the first permanent faint pink color. The following results were obtained. Volumes of NaOH Solution First Sample.....35.22 mL Second Sample.....36.14 mL Third Sample.....36.13 mL Fourth Sample .....36.15 mL Fifth Sample.....36.12 mL Which of the following is the most probable explanation for the variation in the student's results? (A)The burette was not rinsed with NaOH solution. (B)The student misread a 5 for a 6 on the burette when the first sample was titrated. (C)A different amount of water was added to the first sample. (D)The pipette was not rinsed with the HCI solution. (E)The student added too little indicator to the first sample.
(D)The pipette was not rinsed with the HCI solution.
The cooling curve above shows how the temperature of a sample varies with time as the sample goes through phase changes. The sample starts as a gas, and heat is removed at a constant rate. At which time does the sample contain the most liquid? (A)t 1 (B)t2 (C)t 3 (D)t4 (E)t5
(D)t4
5 Fe2+ + MnO4- + 8 H+ ⇄ 5 Fe3+ + Mn2+ + 4 H2O In a titration experiment based on the equation above, 25.0 milliliters of an acidified Fe2+ solution requires 14.0 milliliters of standard 0.050-molar MnO4- solution to reach the equivalence point. The concentration of Fe2+ in the original solution is (A)0.0010 M (B)0.0056 M (C)0.0028 M (D)0.0090 M (E)0.14 M
(E)0.14 M
Which of the following represents the ground state electron configuration for the Mn3+ ion? (Atomic number Mn = 25) (A) l s2 2s22p6 3s23p63d4 (B) 1s2 2s22p6 3s23p63d5 4s2 (C) 1s2 2s22p6 3s23p63d2 4s2 (D) 1s2 2s22p6 3s23p63d8 4s2 (E) 1s2 2s22p6 3s23p63d3 4s1
A. 1s2 2s22p63s23p63d4
2 Al(s) + 6 HCl(aq) → 2 AlCl3(aq) + 3 H2(g) According to the reaction represented above, about how many grams of aluminum (atomic mass 27 g) are necessary to produce 0.50 mol of hydrogen gas at 25ºC and 1.00 atm? (A) 1.0 g (B) 9.0 g (C) 14 g (D) 27 g (E) 56 g
B 9.0 g
Cup: A Material of Spoon: Aluminum Initial Temperatureof Spoon (°C): 20 (for all) Massof Spoon (g): 10.0 Specific HeatCapacity (J/g°C): 0.90 Cup: B Material of Spoon:Ceramic Initial Temperatureof Spoon (°C): 20 (for all) Massof Spoon (g): 10.0 Specific HeatCapacity (J/g°C): 0.80 Cup: C Material of Spoon:Steel Initial Temperatureof Spoon (°C): 20 (for all) Massof Spoon (g): 20.0 Specific HeatCapacity (J/g°C): 0.40 Cup: D Material of Spoon: Silver Initial Temperatureof Spoon (°C): 20 (for all) Massof Spoon (g): 40.0 Specific HeatCapacity (J/g°C): 0.23 Four identical 50mL cups of coffee, originally at 95°C, were stirred with four different spoons, as listed in the table above. In which cup will the temperature of the coffee be highest at thermal equilibrium? (Assume that the heat lost to the surroundings is negligible.) (A) Cup A (B) Cup B (C) Cup C (D) Cup D
Cup B