Practice exam 3 2001 PDF

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Exam containing practice problems for midterm....

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Chemisty 1331 Exam 3 Fall 2001, November 16th, 2001

Version 1

For each question, mark the choice on the answer sheet corresponding to the best answer. 1.

Which of the following bonds is most polar?

A.

B-N

2.

Pick the member of each group with the indicated property.

B.

B-C

C.

C-O

D.

B-S

E.

B-O

C.

C-C, N≡O, C-Cl

i) longest bond C-C C=C C=O C-O ii) strongest bond N-O N=O N≡O iii) stronger bond C-Cl C-Br A. D.

C-C, N-O, C-Cl C=O, N-O, C-Br

B. E.

3.

An atom has the following ionization energies: IE1 = 800 kJ/mol, IE2 = 2,430 kJ/mol, IE3 = 3,660 kJ/mol, IE4 = 25,000 kJ/mol. Which of the following is most likely to be the element?

A.

Li

4.

Choose the element with the most negative (exothermic) electron affinity?

A.

Mg

5.

What is the electron configuration of the Fe2+ ion?

A. E.

[Ar]4s23d6 [Ar]3d5

B.

B.

B.

C-O, N≡O, C-Br None of these is correct

B

P

[Ar]4s23d4

C.

N

D.

O

E. Ne

E.

C.

Ar

D.

Na

C.

[Ar]4s23d8

D.

[Ar]3d6

Cl

6.

Which of the following lists of atoms are arranged in order of decreasing atomic size?

A. D.

Na > K > Rb > Cs C>N>O>F

7.

For which of the following molecules can a Lewis structure that obeys the octet rule be drawn?

A.

SeF4

8.

Which of the following molecules would be expected to have at least one bond angle of 120°?

A.

CO2

9.

From each pair, pick the compound with the higher (more negative) lattice energy.

i)

LiCl or

A. D.

LiCl, CaO, NaF CsCl, CaO, MgO

10.

To which Main Group in the periodic table does X in the ionic compound X2O3 belong?

A.

1A

11.

Select a correct set of quantum numbers (n, l, ml, ms) for the last-added electron in the ground state of germanium.

A. E.

4, 1, 1, -1 3, 1, 0, +1/2

12.

What is the electron configuration of I(Z = 53)?

A. E.

[Kr]5s22d105p5 [Kr]5s24d105p5

B.

B.

CsCl

B.

B. E.

SiF4

C.

NH3

ii)

F > N > B > Be none are arranged in order of decreasing atomic size

NO

C.

CaO

or

CH4

CaS

B. E.

2A

B.

B.

D.

C.

iii)

NaF

PF5

or

3A

D.

E.

B > Be > C > N

XeF2

E.

SF6

C.

LiCl, CaS, MgO

MgO

CsCl, CaS, MgO LiCl, CaO, MgO

3, 1, 1, +1/2

[Kr]5s24d104p5

D.

BH3

C.

5A

E.

6A

C.

4, 1, 0, +1/2

D.

4, 0, 0, +1

C.

[Kr]5s25d105p5

D.

[Kr]4s24d104p5

13.

Consider the following figure that represents a possible Lewis structure for the sulfate anion with the lone pairs omitted. Calculate the formal charge of the sulfur atom. O O

S

O

O A.

0

B.

+1

C.

14.

Which of the following species does not exhibit resonance?

A. D.

nitrate anion carbon dioxide

15.

Which of these statements is FALSE?

A. B. C. D. E.

Among elements in a Main Group those with the largest radii have the smallest electronegativity. Ionic compounds conduct electricity in the solid state The enthalpy change associated with breaking covalent bond is always positive. A covalent bond is stabilized by electrostatic forces between the joined nuclei and their shared electron pairs. The C2H4 molecule has six bonding electron pairs and no lone pairs.

16.

Which of the following is correct?

A. B. C. D. E.

The Lewis structure of SF2 contains 2 lone pairs. The Lewis structure of BH3 obeys the octet rule. The sulfur atom in the Lewis structure of SF4 obeys the octet rule. A triple bond is present in the Lewis structures of both CN- and CO None of these are correct

17.

Which of the following molecules would be expected to be polar [possess a dipole moment]?

A.

CF4

B. E.

B.

CO2

C.

-1

D.

+2

carbonate anion ozone

BF3

D.

NF3

E.

-2

C.

nitrogen dioxide

E.

SF6

18.

Calculate the value of ΔH° for the reaction C2H6 + 2 Cl2 => C2H4Cl2 + 2 HCl given the bond energies (kJ/mol):

H-H 432 kJ/mol C-H 314 kJ/mol H-Cl 427 kJ/mol C-C 347 kJ/mol Cl-Cl 243 kJ/mol C-Cl 339 kJ/mol A. E.

-209 kJ/mol -518 kJ/mol

B.

19.

Which ion is larger in each pair? i) O2- or S2-

A. E.

S2-, Fe2+, S2None of these

20.

The lattice energy for KCl(s) is -690 kJ/mol. Given the information below, calculate the electron affinity of Cl(kJ/mol).

B.

-418 kJ/mol

S2-, Fe3+, S2-

C.

318 kJ/mol

ii) Fe2+ or Fe3+ C.

D.

-318 kJ/mol

D.

S2-, Fe2+, K+

iii) S2- or K+

O2-, Fe3+, K+

IE K(g) = +419 kJ/mol K(s) => K(g) ΔH = +90 kJ/mol Cl2(g) => 2Cl(g) ΔH = +194 kJ K(s) + 1/2Cl2(g) => KCl(s) ΔHrxn = -394 kJ IE, Cl(g) = +1143 A.

+407

B.

-310

E C B E D | D B D E C | C EAD B | D D BAB

C.

-407

D.

-1043

E.

-349...