Exam 2 Review Chem 110 MJ Bojan

CHEM 110 EXAM Exam 2 Mon. Feb. 25

6:30-7:45pm

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CHEM 110 EXAM Exam 2 Mon. Feb. 25

6:30-7:45pm

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Regular Conflict 4:40-5:55 pm 101 Thomas

!   Covers: Lectures 14-22 !   Chapters 6, 7, Organic, 12.1

Format: 28 Multiple Choice questions

See sample practice exams on the Chem 110 Web page: select Handouts.

Atoms form bonds

!   Covalent bonds !   Draw and interpret Lewis structures

!   What is resonance?

Draw and interpret Lewis structures Consider the three molecules N2, N2H4 and NNO. Which one of the following statements is true? The nitrogen–nitrogen bond is:

A. strongest in NNO.

B. longest in N2H4

C. longest in N2

D. weakest in NNO

E. shortest in N2H4

Which one of the following pairs of Lewis diagrams is a correct pair of resonance structures?

Properties of molecules !   Is a molecular polar?

!   Recognize if a molecule has polar bonds !   Be able to use molecular geometry in conjunction with

bond polarity to determine if a molecule is polar or not.

!   Intermolecular Forces !   Be able to predict the important intermolecular forces

given a molecule, organic structure, or Lewis structure. !   Be able to predict trends in boiling or melting point

based on molecular structure. !   Be able to rank a list of molecules in order of increasing

boiling point or melting point.

Make connections between structure and properties!!!

Rank the following molecules in terms of decreasing polarity (largest to smallest).

A. III > II > I

B. I > III = II

C. II = III > I

D. II > III = I

E. II > III > I

F

F

F

Cl

Cl

Cl

Cl

I II III

Which of the molecules below are polar?

I. SbF5 II. KrF2 III. TeCl4

A. I only

B. II only

C. III only

D. II and III

E. I and III

Which one of the following molecules would be expected to have the highest boiling point?

The following molecules are liquids at －100°C. Which of these experience significant hydrogen bonding?

I. CH3F II. CH3NH2 III. CH3OH IV. CH3Br

A. I only

B. II only

C. I and IV

D. II and III

E. All liquids will have significant hydrogen bonding.

Rank the following molecules in terms of increasing boiling point.

A. 1 < 3 < 2

B. 1 < 2 < 3

C. 3 < 2 < 1

D. 3 < 1 < 2

E. 2 < 1 < 3

OHH

C

H

HH1. 2. 3.

Bonding in molecules

!   Be able to determine the hybrid orbitals on a given atom in a molecule

!   Be able to determine how many σ and ! bonds there are in a molecule

!   Know what is meant by delocalized ! bonding.

!   Be able to recognize when/if a molecule has delocalized ! bonds.

Which of the following is the correct orbital

hybridization for O(1), C(2) and N(3) as numbered?

O (1) C (2) N (3)

A. sp3 sp3 sp3

B. sp2 sp3 sp3

C. sp3 sp2 sp3

D. sp sp2 sp3

E. sp sp2 sp2

HO

NH2

1

3

2

How many σ and ! bonds are in the molecule shown below?

A. 9 σ, 3 !

B. 12 σ, 3 !

C. 6 σ, 2 !

D. 10 σ, 2 !

E. 12 σ, 2 !

HOC

O

CH2 C C CH3

Which one of these drawings represents one or more delocalized ! bonds?

A. I only

B. II only

C. III only

D. I and II

E. III and IV

I. II. III. IV.

Organic Chemistry

!   Rules of valence: number of bonds an atoms PREFERS.

!   Use the rules of valence to expand a condensed molecular formula into a Lewis structure

!   Use the rules of valence to interpret carbon backbone structures

!   Be able to identify hydrocarbons (alkanes, alkenes, alkynes and aromatics) (Why do they have these classifications?

!   Recognize isomers: structural and geometric

!   Be able to identify organic functional groups (alcohols, ethers, carboxylic acids, amines, aldehydes, and ketones)

Given the structure below, what is the molecular weight of methyl salicylate, a key ingredient in heat ointments that

promote healing by increasing capillary blood flow?

A. 121 g/mol

B. 133 g/mol

C. 137 g/mol

D. 144 g/mol

E. 152 g/mol

OH O

O

Polyurethane insulators can be formed using the diisocyanate shown below. What is the empirical formula of

the diisocyanate shown?

A. C8H4O2N2

B. C4H4O1N1

C. C4H2O1N1

D. C4H5O1N1

E. C8H8O2N2

A 12.0000 g sample of an organic compound was analyzed and the following results were obtained. What is the molecular formula of the compound that has a molar mass of 206 g/mol?

A. C7H11O

B. C6H15O

C. C13H18O2

D. C12H14O3

E. C14H22O

atom mass

C 9.0828 g

H ???

O 1.8612 g

What is the %C in the molecule shown below?

A. 14 %

B. 41 %

C. 45 %

D. 55 %

E. 59 %

OH

O

O

Shapes of molecules

!   Use VSEPR theory to determine electron domain geometry for atoms with 2, 3, 4, 5, and 6 electron domains

!   Know the characteristic bond angles associated with these geometries.

!   Be able to use electron domain geometries to determine molecular geometries by focusing on the bonded atoms.

!   Know the effect of lone pairs and double bonds on the bond angles of a molecule.

An unknown sample weighs 1.57 g and contains 0.0212 moles of molecules. Identify the molecule.

ON

OH

O

OH

O

HO

OE.

C.

D.

B.A.

Which of the following would you expect to react with Br2?

A. I

B. II, III

C. II, III, IV

D. II, IV

E. all of them

I. Octane II. Hexene III. Benzene IV.Butyne

Identify the structural isomers.

A. I and III only

B. I and IV only

C. II and IV only

D. I, III and IV only

E. III and IV only

OH

OONH2

I II III IV

Which of the molecules below can have geometric isomers?

C

H

CH3 CH3CH2CA.

H

CCH3 CH3CH2

CB.

C. D.CH2

CH3 CH3CH2CH

CH3

C

H

H OHCE.

H

H

H

The molecule shown below is cyclohexane. Which of the following answer choices is a structural isomer of this

molecule? A. i only

B. ii only

C. iii only

D. i and ii only

E. i, ii, and iii

i. ii. iii.

cyclohexane

What are the electron-domain and molecular geometry of iodine trichloride?

electron-domain molecular geometry

A. trigonal bipyramidal trigonal planar

B. tetrahedral trigonal pyramidal

C. trigonal bipyramidal T-shaped

D. octahedral trigonal planar

E. T-shaped trigonal planar

The molecule XeF4 has ______ lone pair(s) on the central Xe atom, and the F－Xe－F bond angle is _____.

A. one, 120o

B. two, 118o

C. zero, 109.5o

D. two, 90o

E. one, 98o

Put the 3 molecules in order of increasing F－X－F bond angle, where X is the central atom.

CF4 OF2 NF3

A. CF4 < OF2 < NF3

B. OF2 < NF3 < CF4

C. CF4 < NF3 < OF2

D. OF2 < CF4 < NF3

E. NF3 < CF4 < OF2