ACS questions copy and paste
Which molecule has a trigonal pyramidal geometry?
A. PCl3
Which is the best explanation for phosphorus favoring formation of P4 over P2 molecules, while nitrogen forms only N2 molecules?
A. Phosphorus-phosphorus π bonds are weaker than nitrogen-nitrogen π bonds.
Which resonance structure contributes the most to the overall bonding in nitrous oxide, N2O?
A. Picture
Two metal samples, labeled A and B, absorb the same amount of heat. Sample A has a mass of 10.0 g, and its temperature increases of 38 degrees Celsius. Sample B has a mass of 20.0 g and its temperature increases by 23 degrees Celsius. Which sample has the greater specific heat capacity?
A. Sample A
Which structure depicts the enantiomer of the diol shown?
A. See Picture
Which compound is an ester?
A. See picture
Which isomer of C4H8O2 has the greatest solubility in water?
A. See picture
Which biomolecule does NOT contain C=O double bonds?
A. Sucrose (a carbohydrate)
In azomethane, H3CNNCH3, what are the molecular geometries around the carbon and nitrogen atoms, respectively?
A. Tetrahedral at carbon, bent at nitrogen
For an endothermic reaction to be spontaneous under standard conditions at constant pressure at some temperature T, which must be true?
A. The entropy change ∆Sº must be positive and greater than ∆Hº/T.
What is the average oxidation state of tin in the mineral abhurite, Sn21Cl16(OH)14O6?
B. +2.00
Romanèchite has the formula Ba2Mn5O10 • 2H2O. What is the average oxidation state of manganese in romanèchite?
B. +3.2
What is the standard Gibbs free energy of formation, ∆Gºf, of NH3(g) at 298 K?
B. -16 kJ/mol Write reaction: 1/2N2(g) + 3/2H2(g) --> NH3(g) ∆G◦ = ∆H◦ − T ∆S ◦ ∆H◦ = 1(-46) - (1/2)(0) - (3/2)(0) = -46 kJ/mol ∆S ◦ = 1(193) − (1/2)(192) − (3/2)(131) = -0.100 kJ/molK ∆G◦ = -46-(298)(-0.100) = -16 kJ/mol
The standard enthalpy of reaction for the dissolution of silica in aqueous HF is 4.6 kJ mol-1 . What is the standard enthalpy of formation of SiF4(g)?
B. -1615.1 kJ/mol
What is the change in standard free energy at 298 K for the conversion of ozone to molecular oxygen as shown in the equation below? 2 O3(g) → 3 O2(g) ∆G° = ???
B. -328 kJ/mol
In the rxn Cl2(g) + 3F2(g) -> 2ClF3(g) the rate of disappearance of F2(g) is 1.0 M/s. What is the rate of appearance of ClF3(g)
B. 0.67 M/s
In the Lewis structure of the chlorate ion, ClO3 - , how many lone pairs of electrons does the chlorine atom have?
B. 1
Photons of what wavelength of light have an energy of 1.00 × 103 kJ mol-1 ?
B. 1.20 × 10-7 m
Below is shown a section of a buret filled with titrant before beginning a titration. What initial volume should be recorded?
B. 1.26
Which reaction has ∆S°rxn > 0? All reactants and products are liquids.
B. See Picture
Which structure best represents the sulfur-containing species produced in the reaction of (CH3)2S with CH3I?
B. See Picture
1.000 g of which salt, when titrated with 0.500 M HCl, gives the titration curve shown?
C. Potassium phenoxide, K(C6H5O) (M = 116.20, pKa of C6H5OH = 9.9)
The oxidation of sulfite ion by triiodide ion is proposed to take place by the following mechanism: I3 - --> I2 + I- fast, unfavorable SO3 2- + I2 → ISO3 - + I- slow ISO3 - + H2O → HSO4 - + I- + H+ fast What rate law is predicted by this mechanism?
C. Rate = k[I3-][SO3^2-] / [H+]
A portion of the phase diagram of elemental sulfur is shown below. Which statement about sulfur is correct?
C. Rhombic sulfur is denser than monoclinic sulfur
Which molecule has a nonzero dipole moment?
C. SF4
Which gas at 600 K has the same effusion rate as methane (CH4) at 150 K?
C. SO2
Which molecule has no unpaired electrons?
C. SO2
In which set are all three species isoelectronic?
C. Se2- , Br- , Rb+
For an irreversible reaction A --> products, the graph of 1/[A] as a function of time is linear. What is the reaction order in A?
C. Second Order Integrated rate law 2nd Order: 1/[A] = kt + 1/[A]o this is linear
Which compound reacts the fastest in electrophilic aromatic substitution reactions (such as with Br2 in the presence of FeBr3)?
C. See Picture
Which is NOT a valid representation of 3-methyl-1- butene?
C. See Picture
Phosphorous acid, H3PO3, is a diprotic acid in aqueous solution (pK1 = 2.0, pK2 = 6.6). Which Lewis structure best represents HPO3 2- ?
C. See picture
How many σ bonds and how many π bonds are present in allene, H2CCCH2?
C. Six σ, two π
Which principle restricts the occupancy of an atomic orbital to no more than two electrons?
C. The Pauli exclusion principle
Lead(II) iodide has a solubility product constant of 1.4 × 10-8 . What is the concentration of I - in a saturated solution of PbI2?
D. 3.0 × 10-3 M
How many hydrogen atoms are in 2.50 g of pharmacolite, CaHAsO4•2H2O (M = 216.0)?
D. 3.48 x 10^22
What is the Ksp of Ca(OH)2 at 298 K?
C. 8.4 x 10^-6
How many oxygen atoms are in 225 g O2?
C. 8.47 x 10^24 225 grams/32 g = moles of O2 moles O2 * 6.022x10^23 molecules = # molecules O2 # molecules O2 * 2 atoms = # atoms of Oxygen
A sealed container contains a gaseous sample at 300.0 K consisting of either pure ethane (C2H6), pure neon (Ne), or a mixture of the two. The pressure inside the container at this temperature is 1.00 atm. When the container is cooled to 150.0 K, the pressure is 0.37 atm. What is the composition of the sample? (The vapor pressure of C2H6 at 150 K is 0.10 atm; the critical temperature of Ne is 44 K.)
C. A mixture of ethane and neon.
A portion of the phase diagram of uranium hexafluoride (UF6) is shown below. Which statements are correct? I. UF6 sublimes at atmospheric pressure. II. At 80 ºC and 1.5 atm, only UF6(g) is present at equilibrium.
C. Both I and II
A reaction has Keq = 20 at 298 K, and Keq increases with increasing temperature between 298 K and 350 K. What may be concluded from these observations? I. ∆G°rxn < 0 at 330 K II. ∆S°rxn > 0 at 330 K
C. Both I and II
If used in an electrochemical cell, which of the following half-reactions would require an inert electrode? I. 2 Cl- (aq) ⇄ Cl2(g) + 2 e- II. Fe(CN)6 3- (aq) + e- ⇄ Fe(CN)6 4- (aq)
C. Both I and II
Which methods would be suitable for determining the concentration of an aqueous solution of KMnO4? I. Visible spectrophotometry (colorimetry) II. Redox titration
C. Both I and II
Which of the following equations correctly describe the change in internal energy, ΔE, of a reaction taking place in a bomb calorimeter? I. ∆E = q II. ∆E = ∆H - V∆P
C. Both I and II
Which reactions are spontaneous under standard conditions? I. 2 Cu+(aq) + Co(s) → Co2+(aq) + 2 Cu(s) II. 3 Co2+(aq) + 2 In(s) → 2 In3+(aq) + 3 Co(s)
C. Both I and II
Which statements correctly describe the geometry of the carbonate ion, CO3 2- ? I. All three carbon-oxygen bond distances are the same. II. All three bond angles are 120º
C. Both I and II
Which structural features contribute to the low strain energy of cyclohexane? I. All bond angles are close to 109.5º. II. All C-H bonds on adjacent carbon atoms are staggered.
C. Both I and II
The vaporization of a liquid at a certain temperature and pressure is spontaneous. For this process, which of the inequalities regarding the Gibbs free energy G and the internal energy E are correct? I. ∆G<0 II. ∆E < ∆H
C. Both I and II When ∆G<0, it's spontaneous. Idk for II tho sorry, just memorize
The molar enthalpy of solution of a salt that dissolves endothermically in water is measured in a coffee-cup calorimeter by weighing a known amount of distilled water into the cup and measuring its temperature, then adding a known mass of the salt to the water and measuring the temperature after the salt dissolves. If some water is initially present in the cup before the weighed amount of water is added, what is the effect on the experiment?
C. Calculated ∆H°soln < True ∆H°soln
Which compound is colorless?
C. CrAsO4
The mineral enargite is 48.41% Cu, 19.02% As, and 32.57% S by mass. What is the empirical formula of enargite?
C. Cu3AsS4 Assume 100g: 48.41 g Cu, 19.02 g As, 32.57 g S Find moles of each (g/MM = moles) Divide by lowest number to find ratio (3 Cu: 1 As: 4 S)
A molecule has the formula C5H10O. Which functional groups might it contain? I. Alcohol II. Ketone
C. Either I or II
Which metal has the highest melting point?
C. Fe Tungsten has highest melting point, Fe is closest to Tungsten
Which element does NOT have multiple allotropes?
C. Fluorine
Copper electrodes are placed into two aqueous solutions of copper(II) sulfate at 25 ºC. One compartment contains a 1.0 M solution while the other compartment contains a 0.10 M solution. The two compartments are connected with a salt bridge and the electrodes are connected by a wire passing through a voltmeter. In what direction do the electrons flow through the wire, and what is the cell potential read on the voltmeter?
C. From the electrode in the 0.10 M solution to the electrode in the 1.0 M solution 30 mV
The electronegativity of gallium (1.8) is greater than that of aluminum (1.6). Which is the best explanation for this difference?
C. Ga has a filled 3d subshell, whose electrons incompletely screen the nucleus
What is the relationship between the two compounds shown?
C. Geometric isomers
One hydrogen in 1-butene is replaced by bromine to give a chiral molecule. Which hydrogen is replaced?
C. Hc
In a study of the reaction below, the concentration of O2(g) is found to be decreasing by 0.042 M min-1. At what rate is the concentration of nitrogen dioxide gas changing? 2 NO(g) + O2(g) → 2 NO2(g)
C. Increasing by 0.084 M min-1
A solid has a melting point of 1710 °C, is soluble in water, and does not conduct electricity in the solid state. What is the most likely nature of the bonding in this solid?
C. Ionic Ionic compounds conduct electricity in aqueous and molten states, but NOT SOLIC. Ions in solids are fixed. Have high melting points and soluble in water.
Atoms of which element have the smallest ionization energy?
C. K Closest to bottom left
A solution of which compound gives a violet flame test?
C. KNO3 Just memorize, no process
What is the correct equilibrium expression for the given reaction? Cu(OH)2(s) + 4 NH3(aq) --> Cu(NH3)4 2+(aq) + 2 OH- (aq)
C. Keq = [Cu(NH3)4 2+][OH-] ^2 / [NH3]4
Which aspect of metallic bonding best accounts for the characteristic malleability of metals?
C. Metals contain delocalized electrons.
Which element is being reduced in the following equation? 3 Cu(s) + 8 HNO3(aq) → 2 NO(g) + 3 Cu(NO3)2(aq) + 4 H2O(l)
C. N
Which compound is NOT considered aromatic?
B. See Picture
A current of 0.44 A is passed through a solution of a ruthenium nitrate salt, causing reduction of the metal ion to the metal. After 25.0 minutes, 0.345 g of Ru(s) has been deposited. What is the oxidation state of ruthenium in the nitrate salt?
A. +2
What is the average oxidation state of tungsten in sodium phosphotungstate, Na3PW12O40?
A. +6.00
What is the standard reduction potential of Cr3+(aq) to form metallic chromium?
A. -0.74 V
The standard enthalpy of formation of hematite, Fe2O3(s), is -825.5 kJ mol-1 . What is the standard enthalpy of reaction for the reduction of hematite with carbon monoxide to give metallic iron as shown below? CO(g) + 1 /2 O2(g) → CO2(g) ∆H°rxn = -283.0 kJ mol-1 Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g) ∆H°rxn = ???
A. -23.5 kJ mol-1
The Ksp of BaSO4 at 298 K is 1.1 × 10-10. What is ∆Gº at 298 K for the following reaction? Ba2+(aq) + SO4 2- (aq) --> BaSO4(s)
A. -57 kJ/mol
The gas-phase bromination of propene has a standard enthalpy of reaction of -122.5 kJ/mol. What is the standard enthalpy of formation of C3H6Br2(g)?
A. -71.2 kJ/mol
Lithium hydrogen carbonate, LiHCO3, decomposes when heated to form Li2O, CO2, and H2O. How many moles of H2O are formed when 0.50 mol LiHCO3 decomposes?
A. 0.25 Write rxn: 2LiHCO3 --> Li2O + 2CO2 + H2O Stoich: 0.5 mol LiHCO3 * (1 mol H2O/2 mol LiHCO3) = 0.25 mol H2O
Ethanol has a normal boiling point of 78.3 ºC and a standard heat of vaporization (ΔHºvap) of 38.6 kJ mol-1. What is the vapor pressure of ethanol at 45.0 ºC?
A. 0.25 atm
Which compound has the highest normal boiling point?
A. 1-butanol, CH3CH2CH2CH2OH
At 120 degrees Celsius and 1 atm pressure, 1.00 L of methane, CH4, reacts completely with excess oxygen to form carbon dioxide and water. What volumes of the two products are produced at this pressure and temperature?
A. 1.00 L CO2 and 2.00 L H2O
Molten sodium chloride is electrolyzed for 10.0 minutes with a constant current of 10.0 A. What mass of sodium metal is produced?
A. 1.43 g
The standard cell potential of the following galvanic cell is 1.562 V at 298 K. Zn(s) | Zn2+(aq) || Ag+(aq) | Ag(s) What is the cell potential of the following galvanic cell at 298 K? Zn(s) | Zn2+(aq, 1.00 × 10-3 M) || Ag+(aq, 0.150 M) | Ag(s)
A. 1.602
Sulfur trioxide is formed from the reaction of sulfur dioxide and oxygen: SO2(g) + ½ O2(g) --> SO3(g) At 1000 K, an equilibrium mixture has partial pressures of 0.562 bar SO2, 0.101 bar O2, and 0.332 bar SO3. What is the equilibrium constant Kp for the reaction at this temperature?
A. 1.86 Kp: Pressure of Products/Pressure of Reactants (coefficients become exponents) 0.332/(0.562)(0.101)^0.5 = 1.86
A 0.300 M solution of HCl is prepared by adding some 1.50 M HCl to a 500 mL volumetric flask and diluting to the mark with deionized water. What volume of 1.50 M HCl must be added?
A. 100. mL M1V1=M2V2 (0.300 M)(500mL)=(1.50 M)(V)
Which would be most suitable for measuring 2.7 mL of ethanol for addition to a reaction with acidified dichromate?
A. 10mL graduated cylinder Beaker is not accurate, flask and pipet are used to measure example 10 mL of solution, not 2.7 mL
What is the electron configuration of the Al3+ ion?
A. 1s^2 2x^2 2p^6
A triprotic acid is titrated with sodium hydroxide to give the titration curve below. What are the pKa values of the three acidic hydrogens?
A. 2.6, 5.0, 8.2
A 2.00 g sample of ice at 0.0 ºC is placed in 50.0 g of water initially at 25.0 °C in an insulated container. What is the final temperature after the system has achieved equilibrium? (For ice, ΔHºfusion = 6.01 kJ mol-1.)
A. 21.0 ºC
The wavelength of one line in the emission spectrum of C is 538 nm. What is the energy of one photon with this wavelength?
A. 3.69x10^-19
Cyclopropane isomerizes exothermically to propene as shown. The C-C single bond in propene has an estimated bond dissociation enthalpy (BDE) of 345 kJ mol-1 , while the C=C double bond in propene has a BDE of 611 kJ mol-1 . Assuming that the C-H bonds in propene and cyclopropane all have the same BDE, what is the estimated BDE of a C-C single bond in cyclopropane?
A. 308 kJ mol-1
First-generation automobile airbags were inflated by the decomposition of sodium azide (M = 65.02): 2 NaN3(s) → 2 Na(s) + 3 N2(g) What mass of sodium azide would be required to inflate a 16.0 L airbag to a pressure of 1.20 atm at 17 ºC?
A. 34.9 g PV=nRT, then use stoich
A fluorescent dye absorbs a photon of light of 485 nm and emits a photon of light at 540 nm. How much energy is lost as heat?
A. 4.17 × 10-20 J
Sodium bicarbonate decomposes at high temperatures according to the following equation: 2 NaHCO3(s) ⇆ Na2CO3(s) + CO2(g) + H2O(g) At a certain temperature, 50.0 g of NaHCO3 is allowed to react in a 3.0 L evacuated vessel. At equilibrium, the total pressure is 6.25 atm, with some of both solids still present. If 100.0 g of NaHCO3 is allowed to react in the same vessel at the same temperature, what will the pressure be at equilibrium?
A. 6.25 atm
At 400 K, this reaction has Kp = 8.2 × 10^-4 . SO3(g) --> SO2(g) + 1 /2 O2(g) What is Kp at 400 K for the following reaction?
A. 6.7 × 10^-7
When copper-64 decays by positron emission, what daughter nuclide is formed?
A. 64Ni
The isotope 226Ra has a half-life for radioactive decay of 1600 y. How long will it take the amount of 226Ra in a sample of 226RaCl2 to decrease by 25%?
A. 660 y
A certain nuclide undergoes beta decay to form 70Ge. If the same nuclide undergoes electron capture instead, what daughter nuclide forms?
A. 70Zn
Which statement regarding the relative energies of monochromatic light with λ = 800 nm and monochromatic light with λ = 400 nm is correct?
A. 800 nm light has half as much energy per mole of photons as 400 nm light
What is the concentration of H2O2 in a solution that is 30.0% by mass hydrogen peroxide and has a density of 1.11 g cm-3?
A. 9.79 M
The graph below shows the forward and reverse rates for a reaction as a function of time. At time t, a catalyst is added to the system, and the forward reaction rate is observed to change as indicated by the solid curve. Which dashed curve best indicates how the reverse reaction rate changes?
A. A
For which element is the +2 oxidation state LEAST common?
A. Al
One Lewis structure of squarate ion, C4O4 2- , is shown below. Which statement best describes the bond distances in the squarate ion?
A. All carbon-carbon bond distances are the same, and all carbon-oxygen bond distances are the same.
The net chemical reaction of photosynthesis is best described as
A. An endothermic reaction that forms sugars.
The formation of NOBr, 2 NO(g) + Br2(g) → 2 NOBr(g) is studied, and the following mechanism is proposed: NO(g) + Br2(g) NOBr2(g) fast, equilibrium NO(g) + NOBr2(g) → 2 NOBr(g) slow In this reaction, NOBr2(g) is best described as
A. An intermediate shows up on product side, then reactant side.
Titration with aqueous triiodide solution to a starch endpoint would be LEAST suitable for which determination?
A. Analysis of nickel content in a Ni/Co alloy
The rate of a reaction is 2.3 times faster at 60 ºC than it is at 50 ºC. By what factor will the rate increase on going from 60 ºC to 70 ºC?
A. By less than a factor of 2.3
The vapor density of which flurocarbon is 6.17 g 1/L at 23 degrees Celsius and 1.00 atm?
A. C3F6
What reaction conditions most effectively convert a carboxylic acid to a methyl ester?
A. CH3OH, HCl
Which species has the strongest carbon-oxygen bond?
A. CO
In which list are the elements in order of increasing first ionization energy?
A. Ca < Si < P < N
For which reaction is ∆Hºrxn equal to ∆Hºf of CaSO3(s)?
A. Ca(s) + 1/8 S8(s) + 3/2 O2(g) → CaSO3(s)
Which solid is least soluble in water at 298 K?
A. CaF2
The bond distance in CO is 112.8 pm, while the bond distance in NO is 115 pm. Which is the best explanation for the shorter bond in CO?
A. Carbon has one fewer valence electron than nitrogen.
Which salt dissolves in water to give a pink solution?
A. Co(CH3COO)2
A mineral containing only copper and oxygen adopts the cubic unit cell shown below. What is the formula of this mineral?
A. Cu2O
A compound with the formula C6H12 does not decolorize bromine in CHCl3 solution. Which compound could this be?
A. Cyclohexane It doesn't react with bromine at room temperature, because there is no double bond
Which gas-phase ion has the greatest number of unpaired electrons in its ground state?
A. Fe^3+
What state of matter corresponds to the diagram below?
A. Gas Moving quickly and randomly, colliding with walls. Spaced out.
What products are formed in the electrolysis of 1.0 M aqueous HBr?
A. H2 at cathode, Br2 at anode Br- is negative and goes to the anode to be oxidized. H+ is positive and goes to the cathode to be reduced
When liquid water converts to solid ice at 0 °C and 1 atm pressure, which of the following changes takes place?
A. Heat flows out of the system
When substances are separated by fractional distillation, which property is least typical of the substance that distills first?
A. Highest molar mass
A solution containing Co(H2O)6 2+(aq), CoCl4 2-(aq), and Cl-(aq) at equilibrium at room temperature is initially pink. When heated, the solution turns blue. Then, when Ag+(aq) is added, the solution turns back to pink. Which statements are correct? I. Co(H2O)6 2+(aq) is pink. II. Formation of CoCl4 2- (aq) from Co(H2O)6 2+(aq) and Cl-(aq) is exothermic.
A. I only
How may an enzyme inhibitor decrease the rate of a reaction catalyzed by the enzyme? I. The inhibitor may bind to the enzyme and block the active site. II. The inhibitor may shift the equilibrium of the reaction toward the starting materials.
A. I only
The following endothermic reaction is at equilibrium in a sealed container. PCl3(g) + Cl2(g) --> PCl5(g) Which of the following changes would result in an increase in the number of moles of PCl5(g) present at equilibrium? I. Increasing T II. Increasing V
A. I only Endothermic means heat is a reactant. Reactant increases, rxn shifts right Increasing Volume favors the side with more gas, rxn shifts left
Under what conditions will the behavior of a real gas best approximate the behavior of an ideal gas? I. High T II. High P
A. I only High temperatures increases KE of particles so IMF doesn't affect them. Low pressures allow particles to spread farther to neglect the size of gas molecules.
Which statement about catalysis is correct?
A. If a catalyst increases the forward rate of a reaction by a factor of two, it must increase the rate of the reverse reaction by a factor of two
A reaction has delta S not >0 and delta H not>0. Which statement about this reaction must be correct?
A. If carried out in a well-insulated flask, the temperature of the reaction mixture will decrease.
The boiling points of the alkali metals decrease from lithium to cesium. Which trend is most closely related to the decreasing boiling points?
A. Increasing atomic radius down the group
Dichromate ion is reduced by chloride ion according to the equation below. If [Cl- ] is decreasing at a rate of 0.37 mol L-1 min-1 , how is the concentration of Cr3+(aq) changing? 14 H+(aq) + Cr2O7 2- (aq) + 6 Cl- (aq) → 2 Cr3+(aq) + 3 Cl2(aq) + 7 H2O(l)
A. Increasing by 0.12 mol L-1 min-1
The concentration of an aqueous solution of a nonvolatile, monoprotic acid is measured first by freezing point depression and then by boiling point elevation. The solution is found to be 0.93 m by freezing point depression and to be 0.82 m by boiling point elevation. What is the best explanation for this discrepancy?
A. Ionization of the acid is markedly exothermic.
In which are the ionic solids ranked in order of increasing melting point?
A. KBr < NaCl < NaF < MgO Size, radius (bigger is less strong)
Which compound will form the most intensely colored 0.01 M aqueous solution?
A. KMnO4 Transition metals produce colored compounds. KMnO4 is the only one with a transition metal.
The melting point of water decreases with increasing pressure. Which is the best explanation for this observation?
A. Liquid water is denser than solid water at 0 degrees Celsius.
The standard enthalpy of formation, ∆Hºf, of the compound MgO(s) is equal to the standard enthalpy change for which reaction?
A. Mg(s) + ½ O2(g) MgO(s) 1 mol MgO(s) is made from Mg and O in their standard states at 298K
1.000 g of a transition metal carbonate, MCO3, is heated to produce the metal oxide and 0.383 g of carbon dioxide (M = 44.01). What is the identity of the metal M?
A. Mn
Which atom has the highest first ionization energy?
A. N
For which of the following reactions would the yield of products at equilibrium NOT increase at a higher pressure?
A. N2(g) + O2(g) --> 2 NO(g)
Which of the following reactions takes place with an increase in entropy under standard conditions?
A. NH4 + (aq) + CH3COO- (aq) --> NH3(aq) + CH3COOH(aq) The other options decrease in chaos and positional states.
Which salt gives a colorless aqueous solution?
A. NaClO4
Sodium halides crystallize in the rock salt structure, which has a cubic unit cell with four formula units per unit cell. A sodium halide has a density of 2.83 g cm-3 and a unit cell edge length of 462 pm. Which compound is it?
A. NaF
Addition of 1 M HBr to 0.1 M solutions of which compound results in evolution of a colorless gas?
A. NaHSO3 HBr + NaHSO3 → H2O + SO2(g) + NaBr SO2 is colorless
The bond in gas-phase O2 (121 pm) is significantly longer than the bond in gas-phase O2 + (112 pm). What is the best explanation for this difference?
A. O2 has one more antibonding electron than O2+
The molar mass of a volatile organic liquid is measured by weighing the mass of an empty flask of known volume, adding some of the liquid, heating the flask in a water bath until the liquid has just vaporized completely, then sealing the flask, letting it cool, and remeasuring the mass of the flask with the remaining organic compound. Which error will lead to a calculated value of the molar mass that is lower than the theoretical value?
A. The flask is not sealed promptly after the last of the compound vaporizes
The diagrams below represent the progress of a reaction of A → B, with molecules of A represented by solid circles and molecules of B represented by open circles. Which statement best describes the reaction at t = 1000 s?
A. The reaction is at equilibrium because the concentrations of A and B are no longer changing
An amine with the formula C4H11N will have which of these properties?
A. Unpleasant odor
Which change in principal quantum number n involves the greatest change in energy?
A. n = 1 → n = 2 in H
Copper(I) oxide, Cu2O, is reduced to metallic copper by heating in a stream of hydrogen gas. What mass of water is produced when 10.00 g copper is formed?
B. 1.417 g Write equation: Cu2O + H2 --> 2Cu + H2O Stoich: 10 g Cu/63.55 g Cu = moles Cu moles Cu/2 moles Cu = moles H2O moles H2O * 18.00 g H2O = g H2O
Calcium fluoride, CaF2, has a molar solubility of 2.1 x 10-4 mol L-1 at pH = 7.00. By what factor does its molar solubility increase in a solution with pH = 3.00? The pKa of HF is 3.17.
B. 1.83 I'm not writing the explanation it's too long, just memorize.
What mass of silver chloride (M = 143.4) will dissolve in 1.00 L of water? The Ksp of AgCl is 1.8 × 10-10
B. 1.92 mg AgCl(s) --> Ag+ (aq) + Cl- (aq) use Ksp and do ice table to find x (molar solubility): 1.34 x 10^-5 mol/L Find mass solubility: 1.34x10^-5 mol/L * (143.4 g/x mols) solve for x.
What is the boiling point of water in a pressure cooker with a pressure of 2.00 atm? (The enthalpy of vaporization of water is 40.7 kJ/mol
B. 121 degrees Celsius
A 5.00 g mixture of potassium sulfide and potassium chloride contains 2.80 g potassium. What percentage by mass of the mixture is potassium sulfide?
B. 19.2%
How many isomers are there of the octahedral coordination complex Co(NH3)3Cl3?
B. 2
Which compound can exhibit geometric isomerism?
B. 2-butene
Sulfuryl chloride (SO2Cl2) decomposes via first-order kinetics. The half-life is 4.1 minutes at a certain temperature. How long does it take for 30% of the SO2Cl2 in a sample to decompose at this temperature?
B. 2.1 min
Which is a possible set of quantum numbers n, l, ml, ms for a valence electron of sulfur (S)?
B. 3, 1, -1, 1/2
If the average carbon-hydrogen bond dissociation enthalpy in ethane is 416 kJ mol-1, what is the bond dissociation enthalpy of the carbon-carbon bond in ethane?
B. 333 kJ/mol
How many π bonds are in cyanogen, NCCN?
B. 4
In the octahedral complex Co(NH2CH2CO2)3, each glycinate ion NH2CH2CO2 - binds to cobalt through its nitrogen atom and one of its oxygen atoms. How many stereoisomers of Co(NH2CH2CO2)3 are possible?
B. 4
The tetragonal unit cell of white tin is shown below. Each circle represents a tin atom, with the gray circles sitting on the four vertical faces of the unit cell. How many tin atoms are contained in this unit cell?
B. 4
A pure sample of a monoprotic acid is dissolved in water. The sample is titrated with sodium hydroxide solution. At the point where 20.0 mL of the NaOH solution has been added, the pH is 4.15. The phenolphthalein endpoint of the titration is observed when 50.0 mL of NaOH have been added. What is the pKa of the acid?
B. 4.33
Polypropylene is made by polymerizing propene, C3H6 (M=42.1). How many molecules of propene must be polymerized to make 3.50 g polypropylene?
B. 5.01 x 10^22
What is the equilibrium constant at 298 K for the disproportionation of uranium(V) in acidic solution as shown below? 2 UO2 +(aq) + 4 H+(aq) ⇄ UO2 2+(aq) + U4+(aq) + 2 H2O(l) Keq = ???
B. 73
What is the pH of a 0.20 M solution of sodium benzoate, Na(C6H5COO)? The Ka of benzoic acid, C6H5COOH, is 6.5 10-5
B. 8.74 CbH5COO is a base: C6H5COO− + H2O --> C6H5COOH + OH− Kb = Kw/Ka = 1.5x10^-10 Ice table: Kb = x^2/0.20 x = 5.5x10^-6 M = [OH-] find pOH, pH = 14-pOH
The specific heat capacity of iron is 0.461 J g-1 K-1 and that of titanium is 0.544 J g-1 K-1 . A sample consisting of a mixture of 10.0 g Fe and 10.0 g Ti at 100.0 ºC loses 200. J of heat to the environment. What is the final temperature of the sample?
B. 80.1 ºC
Titanium has a normal melting point of 1688 degrees Celsius and a molar enthalpy of fusion of 14.15 kJ/mol, the standard molar entropy of liquid titanium is 97.53 J/mol K at 1668 degrees Celsius. What is the standard molar entropy of solid titanium at this temperature?
B. 90.24 J/mol K
The concentration of sulfate ion in a solution is measured by precipitating the sulfate as BaSO4, filtering the precipitate on ashless filter paper, and heating the filter paper and precipitate in a tared crucible with a Bunsen burner. Which error will result in a sulfate concentration that is higher than the actual concentration?
B. A glass fiber filter is used instead of ashless filter paper
A two-dimensional slice through the lattice of a crystalline solid containing two different elements X and Y is shown schematically and to scale below. What type of solid is it?
B. A molecular solid such as IBr
A saturated solution of which silver salt has the highest concentration of Ag+?
B. Ag2CrO4, Ksp = 1.1 × 10^-12
What mode of radioactive decay does 66Cu undergo?
B. Beta Decay
An organize compound contains only carbon, hydrogen, nitrogen, and oxygen. It is 61.71% C, 4.03% H, and 16.00% N by mass. What is its empirical formula?
B. C9H7N2O2
Consider the four gases CO2, N2, CCl4, and He. Which is the correct order of increasing average molecular speed at 100 ºC?
B. CCl4 < CO2 < N2 < He Higher molar mass means slower movement.
Which molecule is planar?
B. COF2
Which gas-phase atom releases the most energy when an electron is added to it?
B. Cl
Which gas-phase molecule is NOT linear?
B. SO2 S in center, with 2 double bonds and 1 lone pair. It is bent.
The endothermic reaction shown below is at equilibrium in a sealed flask, with significant amounts of both Ca(OH)2(s) and CaO(s) present. Which action will increase the amount of Ca(OH)2(s) at equilibrium? Ca(OH)2(s) CaO(s) + H2O(g) ∆H° > 0
B. Decreasing the temperature of the flask
Tert-butyl alcohol reacts with aqueous hydrochloric acid to give tert-butyl chloride. (CH3)3COH(aq) + H+(aq) + Cl- (aq) → (CH3)3CCl(aq) + H2O(l) For this reaction, Rate = k[(CH3)3COH][H+]. With which mechanism is this rate law consistent?
B. Fast: (CH3)3COH(aq) + H+(aq) --> (CH3)3C(OH2) +(aq) Slow: (CH3)3C(OH2) +(aq) → (CH3)3C+(aq) + H2O(l) Fast: (CH3)3C+(aq) + Cl- (aq) → (CH3)3CCl(aq)
A substance A decomposes irreversibly to form B. A plot of ln([A]) as a function of time from the beginning of the reaction until A is 97% consumed is a straight order in A. What is the reaction order in A.
B. First Order
Which compound has the lowest normal boiling point?
B. HCl
100 mL of a 1.0 M solution of hydrochloric acid is gradually added to a stirred mixture containing 0.01 mol calcium hydroxide, 100 mL water, and a small amount of phenolphthalein. What changes are observed? I. The mixture changes from colorless to pink. II. The mixture changes from cloudy to clear
B. II Only
An unknown monoprotic carboxylic acid RCOOH is mixed in a 1:1 mole ratio with its sodium salt, Na(RCOO). A 1.000 g sample of this 1:1 mixture is dissolved in 50 mL water and titrated with 0.5000 M NaOH solution. The pH is measured as a function of added titrant to give the following titration curve: Which statements are correct? I. The molar mass of RCOOH is within 5% of 265 g mol-1 . II. The pKa of RCOOH is within 0.1 unit of 4.2
B. II Only
Which statements about the superoxide ion, O2 - , are correct? I. It has a bond order of 2.0. II. It has exactly one unpaired electron
B. II Only
The molar mass of a solid carboxylic acid is determined by titrating a known mass of the acid with a standardized solution of NaOH to a phenolphthalein endpoint. Which errors will lead to a molar mass that is smaller than the actual molar mass? I. Some of the acid is spilled when being transferred into the titration flask. II.The endpoint is recorded when the solution is dark red in color rather than light pink.
B. II Only I: less acid means less base used. Estimate less moles of acid --> increased molar mass (g/mol) II: dark red means overtitrated (too much base) More base means more acid. Estimate more moles of acid --> decreased molar mass
A galvanic cell is constructed under standard conditions using cobalt in cobalt(II) nitrate solution and indium in indium(III) nitrate solution. Which statements about this cell are correct? I. The standard cell potential is 0.46 V. II. Indium is the anode.
B. II only
Which gas-phase atoms in their ground states are diamagnetic? I. Fe II. Zn
B. II only
A coordination complex M(NH3)2Cl2 can be separated into a pair of geometric isomers. Is this observation consistent with a tetrahedral or a square planar geometry at the metal center?
B. It is consistent only with a square planar geometry
Bromate ion and bromide ion react to form bromine in acidic solution. When the reaction is balanced, which statement about H+(aq) is correct? H+(aq) + BrO3 -(aq) + Br-(aq) → Br2(aq) + H2O(l)
B. Its coefficient is twice the coefficient of Br2(aq).
The diagram is a microscopic view of a snapshot of a substance at equilibrium, with the circles representing molecules and the arrows the molecules' velocities. What state os matter is depicted?
B. Liquid
The bond in F2 has a smaller bond dissociation enthalpy than the bond in Cl2. Which is the best explanation for this difference?
B. Lone pair-lone pair repulsions are stronger in F2 than in Cl2.
Which liquid will NOT react with metallic sodium?
B. Mineral Oil
Which of the following combinations will produce a 0.4 M NaCl solution?
B. Mixing 300 mL of 1.2 M NaOH with 600 mL of 0.6 M HCl
Which gas has the highest molar solubility in water at 25 degrees Celsius and 1 atm?
B. NH3
A solution contains 0.1 M Sr2+ ions and 0.1 M Ag+ ions. Addition of an equal volume of a 0.5 M solution of which reagent will cause precipitation of a strontium salt but not a silver salt?
B. NaF AgF is soluble, SrF is not soluble.
Which gas is most reactive toward 1-hexene?
B. O3
Which molecule has a nonzero dipole moment?
B. O3
Which element is most abundant (by mass) in the Earth's crust?
B. Oxygen
An irreversible reaction, A + B → products, is studied under conditions where [B] >> [A]. When [B] = 0.10 M, a plot of 1/[A] vs. time is linear. When [B] = 0.30 M, the plot of 1/[A] vs. time is indistinguishable from the first plot within experimental error. What is the rate law for this reaction?
B. Rate = k[A]^2
A mechanism for the reaction of nitric oxide with hydrogen to form water and nitrogen gas is proposed below. What rate law is predicted by this mechanism? 2 NO(g) ⇄ N2O2(g) fast, unfavorable equilibrium N2O2(g) + H2(g) → N2O(g) + H2O(g) slow, irreversible N2O(g) + H2(g) → H2O(g) + N2(g) fast, irreversible
B. Rate = k[NO]2 [H2]
The formation of NOBr, 2 NO(g) + Br2(g) → 2 NOBr(g) is studied, and the following mechanism is proposed: NO(g) + Br2(g) NOBr2(g) fast, equilibrium NO(g) + NOBr2(g) → 2 NOBr(g) slow What rate law is predicted by this mechanism?
B. Rate = k[NO]^2 [Br2] k1 forward: k[NO][Br2] k1 backward: k[NOBr2] forward = backward: k[NO][Br2] = k[NOBr2] [NOBr2] = k[NO][Br2] plug into slow rxn: rate = k[NO]^2[Br2]
When the rate of the reversible reaction A+B=C is studied under a certain set of conditions, it is found that the rate of the forward reaction is kf[A]. What can be concluded about the rate law for the reverse reaction under these conditions?
B. Rate=kr[C]/[B]
Electrolysis of water containing sulfuric acid as an electrolyte is carried out as shown and the gases produced at the electrodes collected in two identical tubes, both initially filled with the sulfuric acid solution. After electrolysis has been carried out for a certain time, which picture best represents the appearance of the tubes?
B. See picture
Which conformation of cyclohexane (C6H12) is most stable?
B. See picture
Which period 3 element has these successive ionization energies (in kJ mol-1 )?
B. Si
A strip of metallic zinc is placed in a beaker containing dilute aqueous copper(II) nitrate. Which statement correctly describes what takes place?
B. The mass of the metal strip decreases as the zinc is oxidized.
The acidity of the group 16 hydrides increase going down the group (H2O << H2S < H2Se < H2Te). Which is the best explanation for this trend?
B. The polarizability of the group 16 elements increase going down the group
The reaction of H2(g) with C2H4(g) to form C2H6(g) is catalyzed by metallic platinum. Which statement most accurately describes the impact of changing the catalyst in this reaction?
B. The rate of the reaction would increase if more finely divided platinum were used because the reaction depends on the surface area of the catalyst.
The mineral crocidolite has the formula Na2Fe5(Si4O11)2(OH)2. How many of the iron ions per formula unit are in the +2 oxidation state and how many are in the +3 oxidation state?
B. Three are +2, Two are +3 Find total oxidation states of formula, minus Fe5: -12 This means that Fe5 must have +12 charge 2x + 3y = 12
How many stereoisomers does the square planar complex Pt(NH3)2(Br)(Cl) have?
B. Two
Which statement about unsaturated fats is NOT correct?
B. Unsaturated fats generally have higher melting points than saturated fats with the same number of carbon atoms
For a constant-pressure process, what is the difference between the internal energy change (∆U) and the enthalpy change (∆H)?
B. Work
One unit cell of a crystal containing elements X, Y, and Z is shown below. What is its formula?
B. XYZ3
The standard cell potential of a galvanic cell based on the reaction below is 1.10 V. Which concentrations would result in the largest measured voltage? Cu2+(aq) + Zn(s) → Zn2+(aq) + Cu(s)
B. [Cu2+] = 3.0 M and [Zn2+] = 1.0 M
Which set of quantum numbers could NOT correspond to an electron in a ground-state gas phase Pd atom?
B. n = 3, l = 3, ml = -1, ms = -1/2
Which reaction would yield a single alkene product?
B. see picture
What volume of 18.0 M sulfuric acid must be diluted to 250.0 mL to afford a 0.55 M solution of sulfuric acid?
C. 7.6 mL
The standard reduction potential E° for the reduction of permanganate in acidic solution is +1.51 V. What is the reduction potential for this half-reaction at pH = 5.00? MnO4 - (aq) + 8 H+(aq) + 5 e- → Mn2+(aq) + 4 H2O(l) E° = +1.51 V
C. +1.04 V
Burning 48.0 g of graphite in excess oxygen under standard conditions releases 1574.0 kJ of hear. What is delta H knot forward of CO2(g)
C. -394 kJ 1/mol
A cylinder containing a mixture of CO and CO2 had a pressure of 2.00 atm at 93 definitely Celsius (366 K). The cylinder is then cooled to -90 degrees Celsius (183 K), where CO is still a gas but CO2 is a solid with a vapor pressure of 0.25 atm. The pressure in the cylinder at this temperature is 0.90 atm. What is the mole fraction of CO2 in the cylinder?
C. 0.35
What is the standard cell potential of the following electrochemical cell?
C. 1.03 V
What is the solubility of silver oxalate, Ag2C2O4 (Ksp = 3.5 × 10-11), in a 0.050 M sodium oxalate solution?
C. 1.3 × 10-5 M
1.00 g of hydrated potassium carbonate, K2CO3•nH2O, is heated to 250 degrees Celsius to give 0.836 g anhydrous K2CO3. What is the value of n?
C. 1.5
Methanol is produced industrially by catalytic hydrogenation of carbon monoxide according to the following equation: CO(g) + 2 H2(g) → CH3OH(l) If the yield of the reaction is 40%, what volume of CO (measured at S
C. 1.7 x 10^9
A 2.50 L sample of butane gas (C4H10), measured at 22.0 ºC and 1.20 atm pressure, is combusted completely and the carbon dioxide gas collected at the same pressure and temperature. What volume of CO2 is produced?
C. 10.0 L
The enthalpy of formation of XeF2(g) is -108 kJ mol-1 and the bond dissociation enthalpy of the F-F bond is 155 kJ mol-1 . What is the average bond dissociation enthalpy of a Xe-F bond?
C. 132 kJ/mol Write reaction: Xe(g) + F2(g) --> XeF2(g) 1(F-F) - 2(Xe-F) 155-2x = -108 Solve for X
Chromium is electroplated industrially by the electrolysis of solutions of K2Cr2O7. How much time would be required to deposit 1.00 kg of Cr using a current of 200.0 A?
C. 15.5 h
To 100.0 g water at 25.00 ºC in a well-insulated container is added a block of aluminum initially at 100.0 ºC. The temperature of the water once the system reaches thermal equilibrium is 28.00 ºC. What is the mass of the aluminum block? (The specific heat capacity of Al is 0.900 J g-1 K-1 .)
C. 19.4 g Qwater (gained) + QAl (lost) must equal 0. Qwater = (100 g)(4.184 J/gC)(28-25 C) QAl = m(0.900 J/gC)(28-100C) Qwater + QAl = 0 Solve for m
How many π bonds are in a molecule of propyne, C3H4?
C. 2
An orbital in a ground-state gas-phase As atom has n = 3, l = 1. How many electrons are in this orbital?
C. 2 n=3, l=1 is 3p orbital Arsenic is 3p^6, full shells. 2 electrons in each full orbital.
Which sample has the greatest entropy at a given temperature?
C. 2 mol HBr(g) Most moles of gas (most positional states)
Aluminum crystallizes in a face-centered cubic unit cell with an edge length of 405 pm. What is its density?
C. 2.70 g/cm^3
At equilibrium, a solution contains 0.50 mol each of Cd2+(aq), SCN-(aq), and Cd(SCN)4 2-(aq). What is the solution's volume? Cd^2+(aq) + 4 SCN-(aq) Cd(SCN)4 ^2- (aq) Kf = 1.0 × 10^3
C. 2.8 L
Iodine-131 decays with a half-life of 8.02 d. In a sample initially containing 5.00 mg of 131I, what mass remains after 6.01 d?
C. 2.97 mg 5.00 = (1/2)^(t/8.02) plug in 6.01 for t
A container with 100.0 g of ice at 0 °C is placed in a humid room whose temperature is 40 °C. The ice melts as water vapor condenses into the container. Assuming that all the heat transferred to the container comes from condensation, how much water will have condensed in the container once all the ice is melted and has reached 40 °C? The heat of fusion of ice is 334 J g-1 and the heat of vaporization of water is 2260 J g-1 .
C. 22.2 g
How many isomers have the formula C2H2Br2?
C. 3
How many sulfur atoms are in 3.00 g of iron pyrite, FeS2 (M = 120.0)?
C. 3.01 × 10^22
A 1.00 g sample of a hydrogen peroxide (H2O2) solution is placed in an Erlenmeyer flask and diluted with 20 mL of 1 M aqueous sulfuric acid. To this solution is added 0.0200 M KMnO4 solution via a buret, until a pale purple color persists. This requires 22.50 mL of KMnO4 solution. What is the percent by mass of hydrogen peroxide in the original solution?
C. 3.83% Find ratio of KMnO4:H2O2 (2:5) Use ratio and find remaining mass of H2O2: 22.5 mL * (0.02 mol KMnO4/1000 mL) * (5 mol H2O2/2molKMnO4) * (34.01 g H2O2/1 mol H2O2) = 0.0383 g H2O2
The rate constant of a chemical reaction increases 26% when the temperature is raised from 50 ºC to 55 ºC. What is the activation energy of this reaction?
C. 41 kJ mol^-1
The isotope 44Ti undergoes electron capture. Which daughter isotope is produced?
C. 44Sc
What is the pH of a 0.10 M solution of NH4F? The Ka of NH4 + is 5.6 × 10-10 and the Ka of HF is 6.8 × 10-4 .
C. 6.21
A 0.12 M solution of a monoprotic acid is 2.3% ionized. What is the Ka of this acid?
C. 6.5 x 10^-5 Ice table 2.3 % is used (0.0028 M). Ka = [H+][A-]/[HA] Ka=(0.0028)^2/0.117
A student is using a buret for a titration. What initial buret reading should be recorded?
C. 6.63
A vessel contains 66 g CO2 and 16 g O2 at a pressure of 10.0 atm. What is the partial pressure of CO2?
C. 7.5
An electrolytic cell consists of two copper electrodes immersed in a solution of copper(II) sulfate. What is the result of passing 0.35 A of current through this cell for 1300 s?
C. The mass of the anode decreases by 0.15 g
Which statement best describes the variation of the rate constant of a reaction with temperature?
C. The rate constant typically increases with increasing temperature because increasing the temperature increases the fraction of collisions that result in reaction.
Which is the best way to dispense liquids using a volumetric pipet?
C. The tip of the pipet is submerged below the surface of the liquid and suction is applied using a pipet bulb until the liquid rises above the level of the mark. A gloved finger is then applied to the top of the pipet and the liquid allowed to drain to the mark. The remaining contents are then allowed to drain into the desired container.
How many distinct compounds have the formula C5H12?
C. Three
Toluene, C7H8, has both a higher vapor pressure than water at 25 ºC and a higher normal boiling point. Which statement best explains these observations?
C. Toluene has a lower heat of vaporization than water Lower heat of vap. allows molecules to turn to gas easier, which means higher vapor pressure.
0.100 mol of HF (Ka = 6.6 × 10-4 ) is added to water to make 1.00 L of solution. Which statement is correct at equilibrium?
C. [HF] > [F- ]
An irreversible reaction A + B → C is carried out under various conditions, but always with [B]0 >> [A]0. Plots of 1/[A] as a function of time for each reaction are linear, and the slopes of these plots do not depend on the initial concentration of B. What is the rate law for the reaction under these conditions?
C.Rate = k[A]2
What is the cell potential of the following galvanic cell under the stated conditions at 298 K? Zn(s) | Zn2+(aq, 1.0 × 10-4 M) || AgCl(s) | Ag(s), Cl-(aq, 0.50 M)
D. +1.120 V
What is ∆Eº for this reaction?
D. 0.115
Carbon tetrachloride is produced from methyl chloride and chlorine according to the following equation: CH3Cl(g) + 3 Cl2(g) CCl4(g) + 3 HCl(g) If the rate of formation of CCl4 is measured to be 0.063 M min-1 , what is the rate of disappearance of Cl2?
D. 0.19 M/min 3 mol C2 consumed for 1 mol CCl4 formed: 0.063 M/min * (2 mol Cl2/1 mol CCl4) = 0.19 M/min
The standard reduction potential of oxygen under acidic conditions at 298 K is +1.23 V. What is the standard reduction potential for the four-electron reduction of O2(g) under basic conditions?
D. 0.40 V
What is the concentration of nitrate ions in 40.0 mL of a 0.25 M solution of copper(II) nitrate?
D. 0.50 M
A solution of ammonia, NH3, has pH = 11.50. What is the ammonia concentration? (The pKa of NH4 + is 9.24.)
D. 0.58 M
100.0 mL of 0.500 M CaBr2 and 50.0 mL of 1.00 M NaBr are mixed. What is the concentration of bromide ion in the resulting solution?
D. 1.00 M
Chromium(III) hydroxide has Ksp = 1.6 × 10-30. What is the molar solubility of Cr(OH)3 in a solution whose pH is maintained at 6.00?
D. 1.6 × 10^-6 mol/L
Barium fluoride has Ksp = 1.8 × 10-7. What is the maximum fluoride ion concentration possible in a solution with [Ba2+] = 5.0 × 10-4 M?
D. 1.9 × 10-2 M
What is the pH of a 0.10 M solution of NaCN? The Ka of HCN is 4.9 × 10^-10
D. 11.15
Which is the ground-state electron configuration of gasphase Co2+?
D. 1s^2 2s^2 2p^6 3s^2 3p^6 3d^7
The following data were collected for the reaction of A and B: What is the order of the reaction with respect to A and B?
D. 1st order in A, 2nd order in B
The normal boiling point of 2-propanol, (CH3)2CHOH, is 83 ºC, while that of acetone, (CH3)2C=O, is 56 ºC. What is the principal reason for the greater boiling point of 2- propanol?
D. 2-Propanol experiences stronger hydrogen bonding than acetone. Acetone's strongest IMF is dipole-dipole, while Propanol's is Hydrogen bonding. H-bonding is stronger than dipole-dipole. Boiling point increases with IMF strength.
What is the bond order of O2 +?
D. 2.5
A sample of 0.900 mol N2O is placed in a sealed container, where it decomposes irreversibly to N2 and O2 in a first-order reaction. After 42.0 min, 0.640 mol N2O remains. How long will it take for the reaction to be 90.0% complete?
D. 284 min
Trimesic acid is a triprotic acid with pK1 = 3.1, pK2 = 3.9, and pK3 = 4.7. 100.0 mL of 0.100 M trimesic acid is titrated with 0.500 M NaOH(aq) to give the graph below. What volume of NaOH(aq) has been added at the point marked V on the graph?
D. 30 mL
The isotope cobalt-57 has a half-life of 272 d. How long will it take a sample of 57Co to decay to 38% of its original activity?
D. 380 d
When the chemical equation is balanced, what is the ratio of the coefficient of Ag(s) to the coefficient of H2O(l)? __ Ag(s) + __ NO3 - (aq) + __ H+(aq) → __ Ag+(aq) + __ NO(g) + __ H2O(l)
D. 3:2
How many distinct branched alkanes are there with the formula C6H14?
D. 4
What is the maximum number of monosubstitution products of the aromatic substitution reaction shown?
D. 4
How many completely filled p orbitals are present in a ground state Cl atom?
D. 5
Which solute, when dissolved in 1 kg H2O, will give the solution with the highest boiling point?
D. 50 g glyoxal, HCOCHO
Consider the reaction: H2(g) + I2(g) --> 2 HI(g) Keq = ??? Into a 1.00 L vessel, 1.00 mol H2(g) and 1.00 mol I2(g) are placed at a high temperature. When the reaction mixture stops changing, it is found that 79.0% of the H2(g) has reacted. What is the equilibrium constant for this reaction at this temperature?
D. 56.6
How many electrons in a ground-state As atom in the gas phase have quantum numbers n = 3 and l = 1?
D. 6
A 1.00 g sample of a silver-containing ore is dissolved in dilute nitric acid. The solution is neutralized and then selectively electrolyzed to deposit the silver metal, requiring 670 s of 0.10 A current. What is the mass percentage of silver in the ore?
D. 7.5%
A 5.0 g sample of calcium nitrate (Ca(NO3)2, M = 164) contaminated with silica (SiO2, M = 60.1) is found to contain 1.0 g calcium. What is the mass percent purity of calcium nitrate in the sample?
D. 82% Mass ratio of Ca/Ca(NO3)2: 40.078/164 = 0.244 (every g Ca(NO3)2 has 0.244 g Ca) 1.0 g Ca is used to find how much Ca(NO3)2: 1.0 g Ca/0.244 = 4.1 g Ca(NO3)2 Mass % Purity: g Ca(NO3)2/total g 4.1/5.0 = 82%
In the guanidinium ion, [C(NH2)3] + , what is the best description of the hybridizations of the nitrogen atoms?
D. All three sp^2
Which hydrocarbon is 84.1% carbon by mass?
D. C8H18 8(12.01)/[8(12.01) + 18(1.01) = 84.1%
Which combination of reactants and catalyst will produce methyl propanoate, CH3CH2COOCH3, upon heating?
D. CH3OH and CH3CH2COOH with catalytic H2SO4
A divalent metal ion dissolved in dilute hydrochloric acid forms a precipitate when H2S is bubbled through the solution. Which ion is it?
D. Cd^2+ Cd has smallest solubility in water and not soluble in hydrochloric acid.
Which cycloalkane in its most stable conformation has average internal C-C-C bond angles most different from the value given?
D. Cyclohexane, 120°
Which reaction is not exothermic?
D. Dissolution of solid sodium bicarbonate in water Dilution/dissolution of STRONG acids or bases are exothermic
In a solution prepared by dissolving 0.1 mol NaNO2 in 1.0 L pure water, which species has the lowest concentration?
D. H3O+
A sample of water in a movable piston is maintained at 100.0 ºC with an external pressure p. Which statement best describes the transformation of some of the liquid water into water vapor?
D. It is reversible if p = 1 atm and nonspontaneous if p > 1 atm.
Which potassium salt is 28.9% chlorine by mass?
D. KClO3
What is the principal intermolecular force that must be overcome when n-hexane (C6H14, bp=69 vaporized?
D. London dispersion forces
Which compound contains both ionic and covalent bonds?
D. MgSO4 ionic: Mg and SO4 covalent: S and O
Ammonia (NH3) has a higher normal boiling point (-33 ºC) than its heavier congeners PH3 (bp -88 ºC) or AsH3 (bp -63 ºC). Which is the best explanation for this difference?
D. NH3(l) has extensive hydrogen bonding while PH3(l) and AsH3(l) do not.
A solution of 20.0 g of which hydrated salt dissolved in 200 g H2O will have the lowest freezing point?
D. Na2SO4 • 10 H2O (M = 286) ∆T = i*Kf*m mass is similar (won't affect molality) and Kf is constant, only Van't Hoff can affect Van't Hoff Factors: CuSO4: 2 NiSO4: 2 MgSO4: 2 Na2SO4: 3 Na2SO4 • 10 H2O has highest Van't Hoff --> lowest freezing point
Addition of 6 M HCl to which substance will NOT result in gas evolution?
D. NaNO3 Write each reaction, NaNO3 has all spectator ions.
To what elements are the phosphorus atoms in DNA bonded? I. C II. H
D. Neither I nor II
Two reactions have similar ∆H°rxn values (∆H°rxn (1) ≈ ∆H°rxn (2)), but reaction (1) has a much smaller standard entropy change than reaction (2) (∆S°rxn (1) << ∆S°rxn (2)). At 298 K, which statements about these two reactions must be correct? I. Reaction (1) must have a larger equilibrium constant (Keq (1) > Keq (2)). II. Reaction (1) must have a larger Arrhenius prefactor (A(1) > A(2)).
D. Neither I nor II
The rate constant for an elementary chemical reaction can be affected by which of the following? I. Reactant concentrations II. Product concentrations
D. Neither I or II
The following mechanism is proposed for the oxidation of I- by OCl- in aqueous solution: OCl- + H2O HOCl + OH- fast, reversible HOCl + I- → HOI + Cl- slow HOI + OH- OI- + H2O fast, reversible What reaction orders for OCl-, I-, and OH- are consistent with this mechanism?
D. Order in OCl-: 1 Order in I-: 1 Order in OH-: -1
In which are the ionic compounds listed in order of increasing magnitude of their lattice energy?
D. RbI < LiI < LiF < CaO
Which element is NOT present in DNA?
D. S
14.0 mL of 0.53 M barium nitrate solution and 16.0 mL of 0.44 M sodium sulfate solution are mixed. Which ion is LEAST abundant in solution?
D. SO4^2-
A gas mixture contains 50 mol% H2 and 50 mol% He. 1.00-L samples of this gas mixture are mixed with variable volumes of O2 (at 0 °C and 1 atm). A spark is introduced to allow the mixture to undergo complete combustion. The final volume is measured at 0 °C and 1 atm. Which graph best depicts the final volume as a function of the volume of added O2?
D. See Picture
A pure substance is found to rotate the plane of plane-polarized light. Which compound is it?
D. See Picture
Which structure best depicts the three-dimensional shape of the P4 molecule?
D. See Picture
A student determines the number of moles of water in a hydrated metal oxide by weighing a clean, dry crucible and lid while the crucible is empty, then reweighing the crucible and lid with a sample of the hydrate, heating the crucible and lid with a Bunsen burner and then reweighing the crucible and lid with the sample after cooling to room temperature. Which error will result in too high a value for the amount of water of hydration?
D. Some of the heated oxide is spilled from the crucible before it can be weighed.
Which statement about sulfur, whose phase diagram is shown below, is correct?
D. The conversion of rhombic sulfur to monoclinic sulfur is endothermic
Which statement best describes the structure and bonding in nitromethane, H3C-NO2?
D. The nitrogen atom has a trigonal planar geometry
Chlorine gas is bubbled into a colorless aqueous solution of sodium iodide. Which is the best description of what takes place?
D. The solution turns yellow-brown as iodide reacts with the chlorine.
Which gas has an effusion rate closest to half that of oxygen gas at a given temperature?
D. Xe
In comparing two reactions, the reaction with the greater activation energy always has
D. the rate that varies more with temperature Rate is dependent on concentration of reactants. Also: lnk = -Ea/RT + C