Chem 18835 | Course Paper

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Two students independently determine the volume of water delivered by a 10.00-mL

pipet. Each student takes 8 measurements, then computes the average volume delivered

and the standard deviation. The results are tabulated below.

Average St. Dev.

Student A 10.4 mL 0.7 mL

Student B 10.00 mL 0.02 mL

Which statement best describes the results?

A.A: good precision, good accuracy. B: good precision, good accuracy.

B.A: good precision, poor accuracy. B: poor precision, good accuracy.

C.A: poor precision, good accuracy. B: good precision, poor accuracy.

D.A: poor precision, poor accuracy. B: good precision, good accuracy.

E.A: poor precision, poor accuracy. B: poor precision, poor accuracy.

If 27.9 g LiCl is dissolved in 175 g H2O, what is the weight percent of LiCl in the

solution?

A.0.376%

B.6.78%

C.13.8%

D.15.9%

E.19.0%

One kind of battery used in watches contains mercury(II) oxide. As current flows, the

mercury(II) oxide is reduced to mercury.

HgO(s) + H2O( ) + 2 e“ Hg( ) + 2 OH“(aq)

If 2.3 10“5 amperes flows continuously for 1200 days, what mass of Hg( ) is produced?

A.2.5 g

B.5.0 g

C.9.9 g

D.13 g

E.15 g

In which group of the following groups of the periodic table are all the elements

nonmetals?

A.2A

B.3A

C.5A

D.6A

E.7A

When heated, azomethane decomposes into nitrogen gas and ethane gas.

CH3N=NCH3(g) N2(g) + C2H6(g)

Bond Bond Enthalpy (kJ/molrxn) Bond Bond Enthalpy (kJ/molrxn)

C-H 413 N-N 163

C-N 305 N=N 418

C-C 346 NN 945

Using average bond energies, calculate the enthalpy of reaction.

A.”611 kJ

B.”527 kJ

C.”429 kJ

D.”313 kJ

E.”263 kJ

All of the following species behave as Lewis acids EXCEPT ____.

A.BH3

B.Al3+

C.SO2

D.Al(OH)3

E.NH3

In positron emission tomography (PET), a positron emitted from an unstable isotope

travels a short distance before it is annihilated by

A.an electron, creating a proton that is detected by the instrument.

B.a neutron, creating two gamma rays that travel in opposite directions.

C.an electron, creating two gamma rays that travel in opposite directions.

D.an alpha particle, creating two protons that travel in opposite directions.

E.gamma ray, creating an electron that is detected by the instrument.

Which one of the following sets of quantum numbers is NOT allowed?

A.n = 7, = 0, = 0, ms = +1/2

B.n = 5, = 3, = “2, ms = +1/2

C.n = 4, = 2, = 0, ms = “1/2

D.n = 3, = 1, = “1, ms = +1/2

E.n = 2, = 1, = 0, ms = 0

The following electrochemical cell has a potential of +0.326 V at 25 C.

Pt | H2(g, 1.00 atm) | H+(aq, 1.00 M) || Cl“(aq) | AgCl(s) | Ag

The standard reduction potential,E, of AgCl(s) = +0.222 V. What is the Cl“(aq)

concentration?

A.1.9 10“19 M

B.5.5 10“10 M

C.0.018 M

D.1.03 M

E.1.8 109 M

What is the weight percent of acetic acid in 7.23 m CH3CO2H(aq)?

A.0.718%

B.7.17%

C.11.5%

D.30.3%

E.42.4%

Which of the following chemical equations corresponds to the standard molar enthalpy

of formation of Na2CO3(s)?

A.2 Na(s) + C(s) + 3 O(g) Na2CO3(s)

B.Na2O(s) + CO2(g) Na2CO3(s)

C.Na2(s) + C(s) + 3 O(g) Na2CO3(s)

D.Na2O2(s) + CO(g) Na2CO3(s)

E.2 Na(s) + C(s) + 3/2 O2(g) Na2CO3(s)

How many moles of HCl must be added to 1.0 L of 1.0 M NH3(aq) to make a buffer

with a pH of 9.00? (pKa of NH4

+ = 9.25)

A.0.36 mol

B.0.44 mol

C.0.56 mol

D.0.64 mol

E.1.8 mol

Calculate the lattice energy of NaBr(s), given the following thermochemical equations,

where DIE and DEA are ionization energy and electron affinity, respectively.

Na(s) Na(g) DfH = +107 kJ

Na(g) Na+(g) + e“ DIE = +496 kJ

1/2 Br2(g) Br(g) DfH = +112 kJ

Br(g) + e“ Br“(g) DEA = “325 kJ

Na(s) + 1/2 Br2(g) NaBr(s) DfH = “361 kJ

A.”963 kJ

B.”751 kJ

C.”290 kJ

D.+290 kJ

E.+1403 kJ

Which of the underlined atoms (C1, C2, N, and O) are sp2 hybridized?

A.C1 and C2

B.C1, N, and O

C.N and O

D.O and C2

E.O only

If a chemical reaction occurs in a direction that has a positive change in entropy then

A.the change in enthalpy must be negative.

B.the reaction must be spontaneous.

C.heat goes from the system into the surroundings.

D.the reaction must be exothermic.

E.the disorder of the system increases.

What is the hybridization of the central sulfur atom in sulfur dioxide, SO2?

A.sp

B.sp2

C.sp3

D.sp3d

E.sp3d2

What is the correct name for N2O4?

A.nitrogen oxide

B.dinitrogen tetraoxide

C.nitrogen(II) oxide

D.nitrogen tetraoxide

E.dinitrogen tetraoxygen

What is the correct answer to the following expression?

7.4576 10“2 + 4.11 10“5 + 6 10“4 =

A.7. 10“2

B.7.5 10“2

C.7.52 10“2

D.7.522 10“2

E.7.5217 10“2

What mass of Zn(NO3)2 must be diluted to a mass of 1.00 kg with H2O to prepare 97

ppm Zn2+(aq)?

A.7.8 10“6 g

B.7.8 10“3 g

C.3.3 10“2 g

D.1.3 10“1 g

E.2.8 10“1 g

Which of the following chemical equations depicts an alkylation reaction?

A.C6H6( ) + CH3Cl( ) C6H5CH3( ) + HCl(g)

B.2 CH3OH( ) + 3 O2(g) 2 CO2(g) + 4 H2O( )

C.C6H12( ) C6H10( ) + H2(g)

D.CH2ClCH2Cl(g) + H2(g) CH3CH3(g) + Cl2(g)

E.CHClCHCl(g) CH2ClCH2Cl(g)

What is the net ionic equation for the reaction of aqueous sodium hydroxide and

aqueous iron(II) chloride?

A.Na+(aq) + OH“(aq) NaOH(s)

B.Na+(aq) + Cl“(aq) NaCl(s)

C.Fe2+(aq) + 2 OH“(aq) Fe(OH)2(s)

D.Fe2+(aq) + OH“(aq) FeOH+(s)

E.Fe2+(aq) + 2 Cl“(aq) FeCl2(s)

Which species in the reaction below undergoes reduction?

H2O(g) + CO(g) H2(g) + CO2(g)

A.H2O

B.CO

C.H2

D.CO2

E.None

The standard enthalpy of formation of NaOH(s) is “425.9 kJ/mol and the standard

enthalpy of formation of NaOH(aq, 1 m) is “469.2 kJ/mol. Determine the heat of

solution of NaOH. Will the solution temperature increase or decrease when NaOH is

dissolved in water?

A.”43.3 kJ/mol; increase

B.+43.3 kJ/mol; increase

C.”43.3 kJ/mol; decrease

D.+895.1 kJ/mol; increase

E.”895.1 kJ/mol; decrease

What percentage of the world’s electricity is supplied by nuclear fusion reactors?

A.0%

B.3%

C.8%

D.17%

E.39%

A mass of 0.4113 g of an unknown acid, HA, is titrated with NaOH. If the acid reacts

with 28.10 mL of 0.1055 M NaOH(aq), what is the molar mass of the acid?

A.2.965 10“3 g/mol

B.9.128 g/mol

C.138.7 g/mol

D.337.3 g/mol

E.820.7 g/mol

What is the energy of a photon with a frequency of 1.09 1015 s“1?

A.6.08 10“49 J

B.1.82 10“40 J

C.7.22 10“19 J

D.2.75 10“7 J

E.2.75 102 J

Which equation depicts hydrogen phosphate ion behaving as a Brnsted-Lowry base in

water?

A.HPO4

2″(aq) + H2O( ) H2PO4

“(aq) + OH“(aq)

B.HPO4

2″(aq) + OH“(aq) PO4

3″(aq) + H2O( )

C.HPO4

2″(aq) + H2O( ) PO4

3″(aq) + H3O+(aq)

D.2 HPO4

2″(aq) + O2″(aq) PO4

3″(aq) + H2O( )

E.2 HPO4

2″(aq) + H2O( ) 2 H2O( ) + P2O7(s)

Which one of the following molecules has a chiral center?

Which of the following statements is/are CORRECT?

1/ The atomic radii of transition metals decrease initially, then increase as one moves

from left to right across a period of the periodic table.

2/ The atomic radii of the d-block elements in the 5th and 6th periods in each group are

almost identical.

3/ The densities of the 6th period transition metals are greater than those of either the 4th

or 5th period transition metals.

A.1 only

B.2 only

C.3 only

D.1 and 2

E.1, 2, and 3

The decomposition of phosphine, PH3, follows first-order kinetics.

4 PH3(g) P4(g) + 6 H2(g)

The half-life for the reaction at 550 C is 81.3 seconds. What percentage of phosphine

remains after 195 seconds?

A.2.2%

B.9.8%

C.19%

D.42%

E.58%

A red laser pointer emits light at a wavelength of 488 nm. If the laser emits 7.5 10“4 J of

energy per second in the form of visible radiation, how many photons per second are

emitted from the laser?

A.4.1 10“19 photons/sec

B.5.4 10“16 photons/sec

C.8.9 1014 photons/sec

D.1.8 1015 photons/sec

E.2.5 1018 photons/sec

In which of the following compounds does the oxidation number of the nitrogen

atom(s) equal +3?

A.NH3

B.N2O4

C.N2H4

D.N2O

E.N2O3

For a given reaction, the activation energy is 63.9 kJ/mol. If the reaction rate constant is

4.1 10“3 M“1s“1 at 32.0 C, what is the reaction rate constant at “5.0 C? (R = 8.314

J/Kmol)

A.1.2 10“3 M“1s“1

B.1.4 10“6 M“1s“1

C.1.3 10“4 M“1s“1

D.4.0 10“3 M“1s“1

E.1.3 10“1 M“1s“1