Chapter 12 alkanes

Question 1

What is the initiation with conditions and propagation of when butane reacts with chlorine by radical substitution forming C3H9Cl
Show stages of reaction of C4H10 to form C4H9Cl

Answer 1

initiation
* equation - Cl2 -> 2Cl.
* conditions - ultraviolet conditions
propagation
* C4H10 + Cl. ->C4H9. +HCl
* C4H9 + Cl2 -> C4H9Cl + Cl.

Question 2

Name the mechanism for the reaction of pentane in prescence of ultraviolet radiation to form organic compounds with the formula C5H11Cl

Answer 2

radical substitution

Question 3

State the conditions for propanoic acid reacting with chlorine in a radical substitution reaction

Answer 3

ultraviolet radiation

Question 4

What is homolytic fission

Answer 4

• one electron form the bond pair goes to each atom/radical

Question 5

At room temperature and pressure the first four members of the alkanes are all gases but the first four are all liquids explain this difference in terms of intermolecular forces

Answer 5

• alcohols have hydrogen bonds and london forces
• hydrogen bonds are stronger than london forces

Question 6

Construct an equation for the complete combustion of octane C8H18

Answer 6

C8H18 + 12.5 O2 - > 8CO2 + 9H2O

Question 7

The C-C-C bond angles in cyclohexane are 109.5 state and explain the shape around each carbon atom in cyclohexane

Answer 7

• shape - tetrahedral
• explaination - four bonding pairs repel

Question 8

State the equations for initiation, propagation and termination with the reaction of cyclohexae and bromine forming C6H11Br in prescence of ultraviolet radiation

Answer 8

intitiation
* Br2->2Br.
propagation
* C6H12 + Br. -> C6H11. +HBr
* C6H11. + Br2 -> C6H11Br + Br.
termination
* C6H11. + Br. -> C6H11Br
* C6H11. + C6H11. -> C12H22
* Br. + Br. -> Br2

Question 9

Write an equation for the reaction of cyclohexane and bromine in prescence of UV radiation to form C6H10Br2

Answer 9

C6H12 + 2Br2 ->C6H10Br2 + HBr

Question 10

Name one sttructural isomer of C6H10Br2 formed in reaction between cyclohexane ad bromine

Answer 10

• 1,1-dibromocyclohexane
• 1,2-dibromocyclohexane
• 1,3-dibromocyclohexane
• 1,4-dibromocyclohexane

Question 11

Explain the potential danger of incomplete combustion of hydrocarbons

Answer 11

Carbon monoxide is toxic

Question 12

Describe how a sigma bond forms

Answer 12

overlap of orbitals directly between the bonding atoms

Question 13

State the bond angle and shape around the carbon atom of C=C double bond in propene

Answer 13

• angle - 120 degrees
• shape - triogonal planar

Question 14

Ethane reacts with chlorined by radical substitution describe fully with equations the mechanisms for this reaction

Answer 14

intiation
* Cl2 ->2Cl.]
propagation
* C2H6 + Cl. ->C2H5. + HCl
* C2H5 + Cl2 -> C2H5Cl + Cl.
termination
* Cl. + Cl. -> Cl2
* C2H5. + Cl. -> C2H5Cl
* C2H5. + C2H5. -> C4H10