Chapter 19 Alkanes

Question 1

Define alkanes

Answer 1

Alkanes are saturated organic compounds that contain only single bonds between carbon atoms

Question 2

General formula of alkane

Answer 2

CnH2n+2

Question 3

Definition of saturated

Answer 3

Only contain c-c bonds

Question 4

Are alkanes ionic or covalent compounds?

Answer 4

Covalent compounds

Question 5

Physical properties of alkanes

Answer 5

-low melting and boiling point
-insoluble in water
-soluble in organic solvent

Question 6

Why does melting and boiling point increase?

Answer 6

As the size of the alkane molecule increases, a larger amount of energy is required to overcome the stronger intermolecular forces between the molecules

Question 7

What does viscosity increase?

Answer 7

As the size of the alkane molecule increases, the intermolecular forces between the molecular increases. Hence, the alkane molecules flow less easily

Question 8

Why does flammability decrease

Answer 8

As the size of the alkane molecule increases, the percentage of carbon in the alkane molecules also increases. Hence, larger alkane molecules are less flammable and produce a smokier flame, due to incomplete combustion.

Question 9

Complete and incomplete combustion formula

Answer 9

alkane + excess oxygen = carbon dioxide + water vapour (complete)

alkane + limited oxygen = carbon monoxide + water vapour (incomplete)

Question 10

Conditions of substation reaction

Answer 10

presence of ultraviolet (UV) light, alkane can react with halogens such as chlorine and bromine