CAS CH 49149 | Course Paper

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For which of the following molecules and ions does the central atom have sp2

hybridization? (The central atom is listed first in each formula below.)

A.SO4

2″

B.CO2

C.NOBr

D.SBr2

E.N2O

Identify from the following list of molecules and ions which behave as Lewis acids:

CO2, NH3, BCl3, Fe3+.

A.CO2 and NH3

B.NH3 and BCl3

C.CO2 and Fe3+

D.CO2, BCl3, and Fe3+

E.CO2, NH3, BCl3, and Fe3+

What is the hybridization and the bond angles around the nitrogen atom in an amide?

A.sp hybridization, 180 bond angles

B.sp2 hybridization and 109 bond angles

C.sp2 hybridization and 120 bond angles

D.sp3 hybridization and 109 bond angles

E.sp3 hybridization and 120 bond angles

If a gas effuses 2.165 times faster than Xe, what is its molar mass?

A.12.94 g/mol

B.28.01 g/mol

C.32.00 g/mol

D.60.65 g/mol

E.284.3 g/mol

Diagram 9-1

The molecular orbital diagram below may be used for the following problem(s). For

oxygen and fluorine, the s2p orbital should be lower in energy than the p2p. However,

the diagram will still yield correct bond order and magnetic behavior for these

molecules.

Energy ________ s*2p

________ ________ p*2p

________ s2p

________ ________ p2p

________ s*2s

________ s2s

________ s*1s

________ s1s

Refer to Diagram 9-1. What is the molecular orbital configuration of F2?

A.[core electrons] (s2s)2 (s*2s)2 (p2p)4 (s2p)2 (s*2p)2

B.[core electrons] (s2s)2 (s*2s)2 (p2p)2 (s2p)2 (p*2p)2

C.[core electrons] (s2s)2 (s*2s)2 (p2p)4 (p*2p)4

D.[core electrons] (s2s)2 (s*2s)2 (p2p)4 (s2p)2 (p*2p)6

E.[core electrons] (s2s)2 (s*2s)2 (p2p)4 (s2p)2 (p*2p)4

Erwin Schrdinger developed a model for the behavior of electrons in atoms that is

known as quantum mechanics. Which of the following statements concerning this

model is/are CORRECT?

1/ The energy of an electron is quantized.

2/ The energy of an electron is equal to its mass multiplied by the square of its velocity.

3/ Electrons travel in circular orbits around a nucleus.

A.1 only

B.2 only

C.3 only

D.1 and 2

E.1, 2, and 3

By what (single step) process does osmium-185 change to rhenium-185?

A.a particle emission

B.b particle emission

C.gamma ray emission

D.electron capture

E.neutron capture

When a secondary alcohol is oxidized, the product is a(n) ____.

A.ketone

B.ether

C.ester

D.aldehyde

E.amide

In the NO2

“ ion, each atom can be viewed as sp2 hybridized. Thus, each atom has one

remaining unhybridized p orbital. How many p2p molecular orbitals (including both

bonding and antibonding orbitals) are formed using the unhybridized p orbitals?

A.1

B.3

C.4

D.6

E.12

All of the following statements concerning acid-base buffers are true EXCEPT

A.buffers are resistant to pH changes upon addition of small quantities of strong acids

or bases.

B.buffers are used as colored indicators in acid-base titrations.

C.the pH of a buffer is close to the pKa of the weak acid from which it is made.

D.buffers contain appreciable quantities of a weak acid and its conjugate base.

E.buffers are resistant to changes in pH when diluted with water.

Two isotopes of a given element will have the same number of ____, but a different

number of ____ in their nucleus.

A.protons, electrons

B.electrons, protons

C.protons, neutrons

D.neutrons, protons

E.electrons, neutrons

Which of the following is the largest volume?

A.5.0 102 cm3

B.5.0 10“4 L

C.5.0 103 mL

D.5.0 10“1 L

E.5.0 105 mL

What is the pH of 6.5 10“5 M KOH(aq) at 25 C? (Kw = 1.01 10“14)

A.”4.19

B.1.54

C.4.19

D.9.81

E.12.46

Which of the following statements is/are CORRECT?

1/ A solution is a homogeneous mixture of two or more substances.

2/ A solute is a mixture of a solvent and a soluble compound.

3/ Aqueous solutions are solutions in which water is a solvent.

A.1 only

B.2 only

C.3 only

D.1 and 2

E.1 and 3

Identify the ions present in Na2SO4.

A.Na+, S2-, and O2-

B.Na+, S2+, and O2-

C.Na+ and SO4

D.Na+, S2-, and O2+

E.Na+ and SO4

–

What is the H3O+ concentration of an aqueous solution with a pH of 8.77?

A.1.7 10“9 M

B.5.9 10“6 M

C.1.6 10“4 M

D.5.23 M

E.5.9 108 M

A 3.592 g sample of hydrated magnesium bromide, MgBr2xH2O, is dried in an oven.

When the anhydrous salt is removed from the oven, its mass is 2.263 g. What is the

value of x?

A.1

B.3

C.6

D.8

E.12

A cube has dimensions of 0.60 meters on each side. What is the volume of the cube in

liters?

A.1.8 L

B.1800 L

C.0.22 L

D.22 L

E.220 L

Rubidium has two naturally occurring isotopes. The average mass of Rb is 85.4678 u. If

72.15% of Rb is found as Rb-85 (84.9117 u), what is the mass of the other isotope?

A.0.56 u

B.85.68 u

C.86.91 u

D.86.02 u

E.83.47 u

What is the pH of a buffer that results when 0.40 mol NaHCO2 is mixed with 100.0 mL

of 2.00 M HCl(aq) and diluted with water to 250 mL? (Ka of HCO2H = 1.8 10“4)

A.-0.301

B.3.05

C.3.44

D.3.74

E.4.05

What is the pH of 0.25 M aqueous acetate ion? (Kb of CH3CO2

“ = 5.6 10“10)

A.4.32

B.4.93

C.9.07

D.9.68

E.13.40

The standard enthalpy change for the combustion of 1 mole of propane is “2043.0 kJ.

C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(g)

Calculate DfH for propane based on the following standard molar enthalpies of

formation.

molecule DfH (kJ/mol-rxn)

CO2(g) “393.5

H2O(g) “241.8

A.”1407.7 kJ/mol-rxn

B.+104.7 kJ/mol-rxn

C.”104.7 kJ/mol-rxn

D.”4190.7 kJ/mol-rxn

E.+1407.7 kJ/mol-rxn

For the following reaction,

2 SO3(g) 2 SO2(g) + O2(g)

the equilibrium constant, Kp, is 1.32 at 627 C. What is the equilibrium constant, at 627

C, for the reaction below?

SO2(g) + 1/2 O2(g) SO3(g)

A.”1.15

B.”0.66

C.0.379

D.0.870

E.1.52

A 1.5991 g sample of a hydrocarbon is combusted to give 1.6918 g of H2O and 5.1661

g of CO2. What is the empirical formula of the compound?

A.CH

B.CH2

C.C2H3

D.C3H4

E.C5H8

Place the following atoms in order of increasing atomic radii: K, Na, Be, and Li?

A.Li < Na < K < Be

B.Be < K < Na < Li

C.Be < Li < Na < K

D.K < Na < Li < Be

E.Li < Be < Na < K

Sulfur hexafluoride is produced by reacting elemental sulfur with fluorine gas.

S8(s) + 24 F2(g) 8 SF6(g)

What is the percent yield if 18.3 g SF6 is isolated from the reaction of 10.0 g S8 and

30.0 g F2?

A.40.2%

B.45.8%

C.47.6%

D.54.6%

E.61.0%

Which of the following thermodynamic quantities are state functions: heat (q), work

(w), enthalpy change (DH), and/or internal energy change (DU)?

A.q only

B.w only

C.DH only

D.DU only

E.DH and DU

What is the molar mass of sodium sulfate?

A.55.06 g/mol

B.119.1 g/mol

C.78.05 g/mol

D.142.0 g/mol

E.110.0 g/mol

Sulfur dioxide has a vapor pressure of 462.7 mm Hg at “21.0 C and a vapor pressure of

140.5 mm Hg at “44.0 C. What is the enthalpy of vaporization of sulfur dioxide? (R =

8.314 J/Kmol)

A.0.398 kJ/mol

B.6.33 kJ/mol

C.14.0 kJ/mol

D.24.9 kJ/mol

E.39.8 kJ/mol

If a gallon (3.78 L) of latex paint can cover 365 ft2 of the surface of a wall, what is the

average thickness of one coat of paint (in millimeters)? (12 in = 1 ft, 2.54 cm = 1 in)

A.1.11 10“1 mm

B.2.83 10“1 mm

C.4.64 10“1 mm

D.4.89 10“1 mm

E.3.40 mm

Which of the following chemical equations show oxidation-reduction reactions?

1/ Mg(s) + I2(aq) MgI2(s)

2/ Pb(ClO4)2(aq) + 2 KI(aq) PbI2(s) + 2 KClO4(aq)

3/ Fe2O3(s) + 3 CO(g) 2 Fe(s) + 3 CO2(g)

A.1 only

B.2 only

C.1 and 2

D.1 and 3

E.2 and 3

What mass of O2 is required to produce 5.00 L NO2 at 305 K and 752 mm Hg? (R =

0.08206 Latm/molK)

2 NO(g) + O2(g) 2 NO2(g)

A.0.198 g

B.1.58 g

C.3.16 g

D.5.00 g

E.6.33 g