Day 1 - SLU COMPI Flashcards
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Which of the following would you expect to form the strongest bonds to carbon? A. Li B. Na C. K D. Rb
A
Consider the following reaction at 1600˚C: Br2(g) ↔ 2Br(g).
When 1.05 moles of Br2 are placed in a 2L flask, 2.5% of Br2undergoes dissociation. Calculate the Kp for the reaction. A. 0.20869 B. 0.001346 C. 3.7216 D. 0.0953
B
What will be the likely combination of ionization energy and electron affinity for an element that has a very low electronegativity? A. High ionization energy, high electron affinity B. High ionization energy, low electron affinity C. Low ionization energy, high electron affinity D. Low ionization energy, low electron affinity
D
Consider the reaction: PCl5(g) ↔ PCl3(g)+ Cl2(g)
ΔHrxn = 87.9 kJ/mol
Which of the following will result in the increase in concentration of Cl2 gas? a. Add PCl 3 B. Cool the mixture C. add PCl 5 D. increase the pressure
C
The average atomic mass of Ga is 69.72. Naturally occurring Ga is composed of 60.0% 69Ga, which has an atomix mass of 68.91, and 40.0% 71Ga. What is the atomic mass of 71Ga? a. 69.72 amu b. 69.92 amu c. 70.94 amu d. 71.00 amu
C
All of the following are chemical processes except
a. Liquid vaporizing to form a gas b. The conversion of starch to carbon dioxide and water in an animal c. An acid dissolving a metal d. Rusting of iron
A
In what group of the periodic table is the element with the following electron configuration? [Ar] 4s2 3d10 4p3 a. 1A b. 2A c. 3A d. 5A
D
The vapor pressure of water at 25˚C is 23.756 torr. A solution consisting of 18.913 grams of a non-volatile substance in 36 grams of water has a vapor pressure of 20.234 torr. What is the molecular weight of the solute? a. 62 b. 54 c. 48 d. 39
B
The atomic weight of chlorine is 35.45 and its naturally occurring isotopes are Cl-35 and Cl-37. What is the percentage abundance of Cl-35? a. 95.8% b. 98.7% c. 77.5% d. 75.0%
C
Starting with 1.0 gram of Sr-90, 0.953 grams will remain after 2 years. Calculate the initial activity of Sr-90 in Ci. 1 Curie(Ci)= 3.70 x 10^10 disintegration/sec a. 70 b. 140 c. 210 d. 280
B
Starting with 2-methyl-2-butene, which of the following processes must be used to produce a secondary alcohol? a. Acid-catalyzed hydration b. Oxymercuration-demercuration c. Addition of bromine water d. Hydroboration-oxidation
D
The Lewis structure of SF2 has ___ lone pairs of electrons and ___ double bonds. a. 8,0 b. 6,0 c. 4,1 d. 2,2
A
When a straight chain alkene undergoes sulfuric acid catalyzed hydration, the primary product is a a. primary alcohol b. secondary alcohol c. tertiary alcohol d. quaternary alcohol
B
How many isomers are there of the chlorinated alkane with the formula C3H6Cl2? a. 2 b. 3 c. 4 d. 5
C
Lead (Pb) crystallizes in a face-centered cubic lattice with a unit cell edge of 4.941. What is the density of lead? (l = 10^-8 cm) a. 2.78 x 10-14 g/cm3 b. 2.85 g/cm3 c. 5.70 g/cm3 d. 11.4 g/cm3
D
The energy sublevel that can contain the most electrons is specified by which of the following quantum number descriptions? a. n=2, l=1 b. n=3, l=2 c. n=4, l=3 d. n=5, l=0
C
To answer the following question, you will need to recall for the 14C isotope found in living matter t = 5720 years and the decay rate is 15 decays/g.min. If 20 grams of charcoal scrapings from the wall of a prehistoric cave dwelling are decaying at a rate of 2.0 disintegrations/minute then the writings must be a. 500 yrs old b. 5720 yrs old c. 11000 yrs old d. 22000 yrs old
D
How many monochlorinated product is expected from the chlorination of propane? a. 1 b. 2 c. 3 d. 4
B
A compound containing only C and H gives 0.518 g of H2O and 2.13 g of CO2 when fully combusted in oxygen. What is its simplest or empirical formula? a. CH9 b. C5H3 c. C5H6 d. C3H4
C
Hydrolysis of an ester leads to two compounds. Which of the following pairs compounds is formed from such a hydrolysis? a. an alcohol and an aldehyde b. two alcohols
c. an alcohol and a carboxylic acid
d. a ketone and a carboxylic acid
C
What is the molarity of a KMnO4 solution standardized against 1.356 gram Na2C2O4 requiring 25.1 mL of the solution in acidic medium?
a. 0.161 M b. 0.403 M c. 1.008 M d. 0.856 M
A
The 300 mg sample of impure Na2SO4 (MW= 142.04) was dissolved in sufficient water and the sulfate was precipitated by the addition of 35.00 mL of 0.1022 M BaCl2. The precipitate was removed by filtration and the remaining BaCl2 consumed 6.79 mL of 0.2467 M EDTA for titration to the Calgamite endpoint. Calculate the purity of the sample.
A. 80% B. 85% C. 90% D. 95%
C
25 mL of a monoprotic unknown acid is titrated to an end point with 0.10 M NaOH at 32.2 mL. At the point where 16.1 mL of base has been added, the pH of the solution is 5.5. What is the value of Ka for the unknown acid?
A. 1.6x10-6 B. 3.2x10-6 C. 6.4x10-6 D. 1.3x10-5
B
A closed vessel contains an inert gas at 500 torr and 60degC. What is the total pressure (in torr) inside the vessel after a few drops of liquid B are injected and equilibrium is established at 60degC with B present as both liquid and vapor? The vapor pressure of liquid B at 60degC is 80 torr.
a. 420 torr b. 500 torr c. 560 torr d. 580 torr
D
An EDTA solution was prepared by dissolving the disodium salt in 1L of water. It was standardized using 0.5063 gram of primary standard CaCO3 and consumed 28.50 mL of the solution. The standard solution was used to determine the hardness of a 2L sample of mineral water, which required 35.57 mL of the EDTA solution. Express the analysis in terms of ppm CaCO3.
a. 89 ppm b. 316 ppm c. 158 ppm d. 269 ppm
B
A sample pyrolusite weighing 0.24 gram was treated with excess KI. The iodine liberated required 46.24 mL of 0.1105M Na2S2O3 solution. Calculate the %MnO2 (86.94 g/mol) in the sample.
a. 46.27% b. 30.85% c. 92.54% d. 76.12%
C
A 100 mL water sample was analyzed by Winkler Method. If 7.52mL of 0.0124 M Na2S2O3 was used for titration, determine the ppm of O2 in the water sample.
a. 2.8 b. 3.5 c. 6.4 d. 7.5
D
If 4.27 g of sucrose, C12H22O11 are dissolved in 15.2 g of water, what will be the boiling point of the resulting solution? (Kb for water = 0.512 K/m. The normal boiling point of water is 100degC)
a. 101.64 degC
b. 100.42 degC
c. 99.62 degC
d. 100.73 degC
B
A 1.5 gram sample of impure aluminum chloride was dissolved in water and treated with 45.32 mL of 0.1000 M AgNo3 using K2CrO4 as indicator. Express the analysis in %AlCl3 (MW= 133.33).
a. 40.28% b. 13.43% c. 4.48% d. 27.36%
B
A 10.0 gram sample of cooked-ham was pureed with 200 mL of water, filtered and the resulting solution containing dissolved potassium nitrite was acidified. This solution was treated with 25.0 mL of 0.00514 M KMnO4 and was back titrated with 14.97 mL of 0.01678 M FeSO4. Calculate the amount of nitrite (46.01 g/mol) in ppm.
a. 450
b. 900
c. 1350
d. 1800
B
Silver crystallizes with a face-centered cubic unit cell. The radius of a silver atom is 0.144 nm. Calculate the density of solid silver. Ag= 107.87 g/mol
a. 24.8 g/ml
b. 21.2 g/ml
c. 15.7 g/ml
d. 10.6 g/ml
D
The law relating the solubility of the gas to its pressure is called
a. Raoult’s Law b. Distribution Law c. Henry’s Law d. Arrhenius Law
C
How many moles of sugar must be added to 100 g to lower the freezing point of the solution by 1degC? The value of Kf for water is -1.86 K/m.
a. 0.5 b. 0.27 c. 0.054 d. 0.027
C
Absolute zero may be regarded as that temperature at which
a. all gases become liquids
b. molecular motion ceases
c. all substances are solids
d. water freezes
B
In the equation for the reaction of potassium iodide (KI) and sulfuric acid (H2SO4), which statement is true?
8KI(aq) + 9H2SO4(aq) → 4I2 (s) + 8KHSO4(aq) + H2S(g) + 4H2O(l)
a. The reducing agent is H2SO4
b. The oxidizing agent is KI
c. The substance reduced is H2SO4
d. The substance oxidized is KHSO4
C
Ethanol is to be used in an automobile carburetor that is adjusted to give a 9:1 air -fuel ratio (mass ratio). If the temperature in the manifold is 60 ˚F and the pressure is atmospheric. What percentage of the alcohol will be evaporated assuming that equilibrium between vapor and liquid is reached? Vapor pressure of ethanol at 60 ˚F is 33.75 mmHg.
a. 56% b. 76% c. 66% d. 90%
C
The correct ordering of the relative solubility of AgCl(s) in water and aqueous solutions of 0.1 M silver nitrate and 0.1 M ammonia is: (1) in pure water, (2) in 0.1M AgNO3, (c) in 0.1 M aq NH3
a. 1>3>2
b. 2>3>1
c. 3>1>2
d. 3>2>1
C
Fe crystallizes in a body-centered cubic lattice. The density of iron is 7.86 g/cm3. Calculate the atomic radius of iron in angstrom.
a. 1.24 b. 2.48 c. 0.62 d. 0.62
A
A solution of 0.72% wt HCl, freezes at -0.706 ˚C. Calculate the apparent molecular weight of HCl.
a. 38.2 b. 37.8 c. 37.1 d. 36.5
A
What moves between the two half-cells of a galvanic cell?
a. electrons only
b. ions only
c. ions and electrons
d. the cells are separated from each other so that there will be no transfer between them
C
Which of the following is an example of a thermoset polymer?
a. formica
b. polyethylene
c. polystyrene
d. poly(vinyl)chloride
A
In which of the following molecules (all linear and linked together as written) is the carbon an sp2 hybrid?
a. FCCF b. OCCO c. NCCN d. none of the choices
B
Which of the following is a detergent?
a. fatty alcohol
b. alkyl benzene sulfonate
c. fatty acids
d. methyl chloride
B
Type of wastewater treatment that employs biological methods to remove fine suspended, colloidal and dissolved organics by biochemical oxidation.
a. primary treatment
b. secondary treatment
c. tertiary treatment
d. minor treatment
B
The process of fermentation can be considered to be
a. oxidation
b. dehydration
c. anaerobic respiration
d. aerobic respiration
C
Process of converting nitrogen gas to ammonia is called
a. ammonification
b. denitrification
c. nitrogen fixation
d. ammonolysis
C
Nutrient for cellular growth is called
a. protein
b. substrate
c. carbohydrate
d. lipid
A
The reduction of carbon dioxide with magnesium powder and turnings releases energy and is therefore (exothermic, endothermic) and the expanding of carbon dioxide from an extinguisher is (isothermal, adiabatic).
a. exothermic, isothermal
b. exothermic, adiabatic
c. endothermic, isothermal
d. endothermic, adiabatic
B
A water solution of molasses contains 10% by weight sucrose (C12H22O11). The CO2 formed in the reaction can be considered having negligible solubility in the solution and the last 10% of the sugar can be assumed unchanged. The weight percent of ethyl alcohol in the solution after 90% of the sucrose has been converted to ethyl alcohol by fermentation is
a. 6.5% b. 5.6% c. 5.1% d. 6%
C
It is desired to reduce the bacterial count of polluted water from 8 million organisms per mL to 17 organisms per mL. The number of completely mixed chlorine contact chambers in series, each having a detention time of 40 minutes, that would be required if the first order removal rate constant is 8 per hour is
a. 5 vessels
b. 7 vessels
c. 10 vessels
d. 8 vessels
B
When 1.827 g of a hydrocarbon, CxHy, was burned in a combustion analysis apparatus, 6.373g of CO2 and 0.7829 g of H2O were produced. In a separated experiment the molar mass of the compound was found to be 252.31 g/mo. Determine the empirical formula and molecular formula of the hydrocarbon.
a. EF: C4H2; MF: C23H15
b. EF: C6H7; MF: C15H8
c. EF: C7H4; MF: C17H10
d. EF: C5H3; MF: C20H12
D
Which of the following units of concentration will change in value for a particular solution if the temperature changes?
a. mole fraction
b. molarity
c. molality
d. none will change
B
One way to reduce air pollution is to remove potential pollutant gases from an exhaust stream before they are released into the air. Carbon dioxide can be removed from a stream of gas by reacting it with calcium oxide to form calcium carbonate. If we react 5.50 L of CO2 at STP with excess CaO, what mass of calcium carbonate will form?
a. 12.5 g b. 34.8 g c. 45 g d. 24.6 g
D
Suppose that you have a part that requires a tin coating. You’ve calculated that you need to deposit 3.60 g of tin to achieve an adequate coating. If your electrolysis cell (using Sn2+) runs at 2.00 A, how long must you operate the cell to obtain the desired coating?
a. 48.8 mins b. 50.5 mins c. 37.2 mins d. 68.3 mins
A
A piece of cloth is discovered in a burial pit in the southwestern United States. A tiny sample of the cloth is burned to CO2, and the 14C/12C ratio is 0.250 times the ratio in today’s atmosphere. How old is the cloth?
a. 11500 yrs
b. 15000 yrs
c. 24800 yrs
d. 28300 yrs
A
Which of the following statements is true?
a. Oxidations always have positive potential and reductions have negative potentials.
b. Half-reactions that have negative half-cell potentials cannot be part of a galvanic (spontaneous) cell under standard conditions.
c. An unreactive metal like gold is very difficult. Therefore, it is very difficult to reduce gold ions to gold metal.
d. Assigning a potential of 0 V to the hydrogen ion/hydrogen gas electrode is purely arbitrary and it could have been assigned any other value.
D
In a laboratory experiment, 2.175 g of lysine, an amino acid containing C, H, O, N, underwent combustion to produce 3.94 g of CO2 and 1.89 g H2O. In another experiment, 1.873 g of lysine was burned and formed 0.436 g of NH3. The molar mass of lysine is 150 g/mol. Determine empirical and molecular formula of lysine
a. EF: C2H2O ; MF: C6H14N2O2
b. EF: CH2N2O ; MF: C7H12N2O
c. EF: C3H2NO ; MF: C6H14N2O2
d. EF: C4H3N2O ; MF: C8H16NO2
C
All of the following are true concerning the calculation of the formula of a compound from the percentage composition of its elements only EXCEPT
a.It is assumed that the atoms of the elements are combined in ratios of reasonably small whole number.
b. The calculation can be based on the idea of starting with 100 g of compound.
c. The actual molecular formula can be calculated.
d. The relative ratios of the numbers of the different atoms in the compound can be determined.
C
The reduction of carbon dioxide to carbon monoxide would best be successfully carried out by reaction with
a. carbon
b. oxygen
c. carbon and oxygen
d. magnesium
D
All of the following are assumptions made in the Bohr theory EXCEPT
a. The forces of circular motion and coulombic attraction exactly balance.
b. The electron in its orbit neither absorbs or emits energy.
c. The electron can occupy only certain orbits
d. The nucleus consists of protons and neutrons
D
A chemist requires 1.5 M hydrochloric acid, HCl, for a series of reactions. The only solution available is 6.0 M HCl. What volume of 6.0 M HCl must be diluted to obtain 5.0 L of 1.5 M HCl?
a. 0.76 L
b. 2 L
c. 1.3 L
d. 3.2 L
C
Which of the following cannot be determined from the molecular formula of the compound C5H12?
a. the molecular mass
b. the mass percent of the compound that is C
c. the mass percent of the compound that is H
d. density of compound
D
Assume that you have a cell that has an iron(II) concentration of 0.015 M and an H1 concentration of 1.0 3 1023 M. The cell
temperature is 38°C, and the pressure of hydrogen gas is maintained at 0.04 atm. What would the cell potential be under these conditions?
a. 0.56 V b. 0.35 V c. 0.45 V d. 0.67 V
B
What is the standard cell potential for the following galvanic cell?
Cu(s) | Cu2+ (1M) || Ag+ (1M) | Ag(s)
a. 0.357 V
b. 0.143 V
c. 0.462 V
d. 0.280 V
C
Which of the following is not a form of electromagnetic radiation?
a. light
b. radiated heat
c. sound
d. microwaves
C
Suppose that we wish to study the possible galvanic corrosion between zinc and chromium, so we set up the following cell:
Cr(s) | Cr2+ (aq) || Zn2+(aq) | Zn(s)
What is the chemical reaction that takes place, and what is the standard free energy change for that reaction?
a. -28.4 kJ
b. -15.7 kJ
c. -32.5 kJ
d. -45.6 kJ
A
Which of the following is one of the principal gases that is responsible for acid rain?
a. CH4
b. SF6
c. Cl2
d. SO2
D
An electrolysis cell that deposits gold (from Au1(aq)) operates for 15.0 minutes at a current of 2.30 A. What mass of gold is deposited?
a. 3.33 g
b. 4.23 g
c. 5.67 g
d. 2.39 g
B
The Solvay process is important in the commercial production of sodium carbonate (Na2CO3), which is used in the manufacture of most glass. The last step in the Solvay process is the conversion of NaHCO3 (sodium bicarbonate, or baking soda) to Na2CO3 by heating.
2 NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)
In a laboratory experiment, a student heats 42.0 g of NaHCO3 and determines that 22.3 g of Na2CO3 is formed. What is the percentage yield of this reaction?
a. 84.2%
b. 75.7%
c. 67.0%
d, 53.2%
A
The equilibrium constant for the reaction of chlorine gas with phosphorus trichloride to form phosphorus pentachloride is 33 at 250°C. If an experiment is initiated with concentrations of 0.050 M PCl3 and 0.015 M Cl2, what are the equilibrium concentration of all three gases? Cl2(g) + PCl3(g) ↔ PCl5(g)
a. [PCl5] = 0.0054 M ; [Cl2] = 0.006 M ; [PCl3] = 0.067 M
b. [PCl5] = 0.0075 M ; [Cl2] = 0.004 M ; [PCl3] = 0.052 M
c. [PCl5] = 0.0088M ; [Cl2] = 0.006 M ; [PCl3] = 0.041 M
d. [PCl5] = 0.0063 M ; [Cl2] = 0.007 M ; [PCl3[ = 0.042 M
C
Not all pollution is due to human activity. Natural sources, including volcanoes, also contribute to air pollution. A scientist tries to generate a mixture of gases similar to those found in a volcano by introducing 15.0 g of water vapor, 3.5 g of SO2 and 1.0 g of CO2 into a 40.0-L vessel held at 120.0°C. Calculate the partial pressure of each gas and the total pressure.
a. P total = 0.543 atm
b. P total = 0.734 atm
c. P total = 0.856 atm
d. P total = 0.623 atm
B
When hydrogen gas reacts with iodine gas at elevated temperatures, the following equilibrium is established:
H2(g) + I2(g) ↔ 2 HI(g)
A student measured the equilibrium constant as 59.3 at 400°C. If one trial begins with a mixture that includes 0.050 M hydrogen and 0.050 M iodine, what will be the equilibrium concentrations of reactants and products?
a. [H2] = 0.03 M ; [I2] = 0.03 M ; [HI] = 0.16 M
b. {H2] = 0.01 M ; [I2] = 0.01 M ; [HI] = 0.16 M
c. [H2] = 0.01 M ; [I2] = 0.01 M ; [HI] = 0.08 M
d. [H2] = 0.03 M ; [I2] = 0.03 M ; [HI] = 0.08 M
C
The explosive known as RDX contains 16.22% carbon, 2.72% hydrogen, 37.84% nitrogen, and 43.22% oxygen by mass. What is the empirical formula of the compound?
a. C2HNO2
b. CH2NO2
c. CH2N2O2
d. C2H2N2O
C
All of the following are true about a balanced equation except
a. It always tells the exact manner in which elements and compounds in the equation will react.
b. It is necessary for doing stoichiometric calculations.
c. It can be used for determining chemical equivalences.
d. It is a useful method for describing the nature of a chemical reaction.
A
The half-life of carbon-14, used in radiocarbon dating, is 5730 years. What is the decay constant for carbon-14?
a. 11.21 x 104 /yr
b. 15.32 x 104 /yr
c. 8.57 x 104 /yr
d. 19.63 x104 /yr
A
Which of the following atoms has the largest number of unpaired spins?
a. C
b. K
c. P
d. F
C
Aqueous solutions of sodium hypochlorite (NaClO) can be used in the synthesis of hydrazine (N2H4). Hydrazine has often been used as a rocket fuel, and a derivative of hydrazine is used as a fuel for engines in the orbital maneuvering system of the space shuttle. A solution is prepared by dissolving 45.0 g of NaClO in enough water to produce exactly 750 mL of solution. What is the molarity of the solution?
a. 0.784 M
b. 0.806 M
c. 0.657 M
d. 0.925 M
B
The active electrophile in the nitration of aromatic ring
a. NO2-
b. NO-
c. NO2+
d. HNO2+
C
The Sandmeyer reaction is used to prepare
a. phenols
b. halo compounds
c. diazo compounds
d. nitro compounds
B
During hydrogenation of oils which of the following catalyst is commonly used.
a. Ni
b. Pd
c. Fe
d. V2O5
A
Addition of an alcohol to acyl halides produces
a. carboxylic acid
b. ester
c. carboxamide
d. none of these choices
B
When ammonium cyanate is heated, we get
a. ammonium carbonate
b. carbon monoxide
c. urea
d. carbon dioxide
C
Formalin is an aqueous solution of
a. formic acid
b. furfuraldehyde
c. formaldehyde
d. fluorescin
C
Which of the following are constitutional isomers of trans-1,2-dimethylcyclopentane?
a. I, III, IV
b. II, IV, V
c. II, III, V
d. III, IV, V
A
Which of the following carbocations has the highest energy?
a.
b.
c.
d.
A
Boiling point of acetone is
a. 69 degC
b. 75 degC
c. 56 degC
d. 90 degC
C
The normal electronic configuration of a molecule is known as its __________.
a. ground state
b. excited state
c. valence electron
d. wavelength
A
The number of xylene isomers is
a. 1
b. 2
c. 3
d. NOTA
C
Which one of the following compounds does not react with bromine?
a. ethylamine
b. phenol
c. chloroform
d. propene
C
Lindlar’s catalyst is used to make _____________.
a. cis-alkenes from alkynes
b.trans-alkenes from alkynes
c.alcohol from alkynes
d. alkanes from alkynes
A
A liquid hydrocarbon is converted into a mixture of gaseous hydrocarbons by
a. cracking
b. oxidation
c. hydrolysis
d. ammonification
A
Homolytic formation of two reactive species with unpaired electrons.
a. initiation
b. propagation
c. termination
d. AOTA
A
Which statement does not describe a transition state?
a. Possesses a definite geometry
b. Maximum on the potential energy diagram
c. Structure can be determined experimentally
d. can not be isolated
C
An enzyme that catalyzes the dehydration of malate in the citric acid cycle.
a. enolase
b. fumarase
c. lewisite
d. nota
B
Which of the following properties are not identical for constitutional isomers?
I. molecular formula
II. molecular weight
III. order of attachment of atoms
IV. physical properties
a. I, IV
b. II, III
c. I, II
d. III, IV
D