6. Organic Chemistry I

Question 1

1. Complete combustion of alkanes

Answer 1

• burning with excess oxygen
  e.g. C3H8 + 5O2&raquo_space; 4H2O + 3CO2

Question 2

2. Incomplete combustion of alkanes

Answer 2

• burning with a limited amount of oxygen
  e.g. C2H6 + 2O2&raquo_space; C + CO + 3H2O

Question 3

3. Free radical substitution of alkanes

Answer 3

1. Initiation - the halogen is broken down in the presence of UV light.
   Cl2 → 2Cl*
2. Propagation - a hydrogen is replaced, and the Cl* radical is reformed as a catalyst
   Cl* + CH4 → *CH3 + HCl
   CH3 + Cl2 → CH3Cl + Cl
3. Termination - two radicals join to end the chain reaction and form a stable product.
   *CH3 + *CH3 → C2H6

Question 4

General Formula of Alkanes

Answer 4

CnH2n+2

Question 5

General Formula of Alkenes

Answer 5

CnH2n

Question 6

1. Reaction of Alkenes with Hydrogen

Answer 6

• Produces Alkanes
• Electrophilic addition
• Nickel catalyst &150°C
• Addition/Reduction reaction
  e.g. C2H4 + H2 -> C2H6

Question 7

2. Reaction of Alkenes with Halogens

Answer 7

• Produces dihalogenoalkanes
• Electrophilic addition
• Heterolytic bond fission
• e.g. C2H4 + Br2 -> CH2Br CH2Br

Question 7

3. Reactions of Alkenes with Hydrogen Halides

Answer 7

• Produces halogenoalkanes
• Electrophilic addition
• Heterolytic bond fission
  e.g. CH3CH=CH2 + HBr -> CH3CHBrCH3

Question 8

4. Reactions of Alkenes with Steam

Answer 8

• Produces Alcohols
• H3PO4 / 300°C / 60 atmospheres
• CH2=CH2 + H2O (g) -> C2H5OH

Question 9

Define Nucleophile

Answer 9

Electron pair donator

Question 10

Define Electrophile

Answer 10

Electron pair acceptor

Question 11

1. Reaction of Halogenoalkanes with Aqueous Potassium Hydroxide - NaOH

Answer 11

• Produces Alcohols
• Nucleophilic Substitution
• OH- acts as a nucleophile
  e.g. CH3CH2CH2Br + KOH -» CH3CH2CH2OH + KBr

Question 12

2. Reaction of Halogenoalkanes with Ethanolic Potassium Hydroxide - NaOH

Answer 12

• Produces Alkenes
• Elimination reaction
  CH3CH2CH2Br + KOH -» CH3CH2=CH2 + KBr + H2O

Question 13

3. Hydrolysis Reaction of Halogenoalkanes

Answer 13

• H2O acts as a nucleophile
  CH3CH2X + H2O -» CH3CH2OH + X- + H+
• Use aqueous solver nitrate to test for halides

Question 14

4.