Formulas, Structures, Isomers, and Boiling Points

Chemistry

Chemical Molecular Formula

Structural Formula

CondensedFormula

Methane CH4 CH4

Ethanoic Acid

C2H4O2 CH3COOH

Glucose C6H12O6CHO(CHOH)4CH2OH

C H

H

H

H

C O H

O

C

H

H

H

C H O H

C HO H

C H O H

C HO H

C H

O

C H 2

O H

Why Molecular Formulas Do Not Always Work Draw C4H10

Isomer- Same molecular formula, different arrangement of atoms

Constitutional isomers Isomers have different

physical and chemical properties

CH2 CH3CH2CH3

CH

CH3

CH3CH3

See if you can figure this out… Draw & name all isomers of C5H12 (3 total!)

Pentane

2-methylbutane2,2-dimethylpropane

See if you can figure this out… Draw & name all isomers of C6H14 (5 Total!)

Hexane

2-methylpentane

3-methylpentane

2,3-dimethylbutane

2,2-dimethylbutane

Cis/Trans Isomers Stereoisomers Molecules cannot

rotate around a double bond

Cis: Similar groups on the

same side

Trans: Similar groups on the

opposite side

C H 2 C H 3

C

H

C

C H 3

H

Trans-2-pentene

CH 2 CH 3

C

H

C

CH 3

H

Cis-2-pentene

Hydrogenation of Triglycerides Food industry

hydrogenates oils to control the texture

Leads to creation of trans-fats

Linked to LDL cholesterol build-up in the arteries

Boiling Points

Boiling Points increase with increasing Mr (molar mass) Van der Waals Forces

increase

Branching decreases Van der Waals forces, and therefore decreases boiling point

Alkane B.P. (ºC)

Methane, CH4 -164Ethane, C2H6 -89

Propane, C3H8 -42Butane, C4H10 -0.5

Pentane, C5H12 36Hexane, C6H14 69Heptane, C7H16 98Octane, C8H18 125

Put the Following in order from Lowest B.P. to Highest B.P.1.

2.

3.

4.

5.