Haloalkane

Question 1

Reactivity of primary-tertiary haloalkane

Answer 1

1. C-X bond in tertiary is weakest
2. tertiary is most reactive

Question 2

Nucleophile

Answer 2

1. ion or molecule
2. electron pair donor
3. forms new covalent bond

Question 3

Haloalkane to alcohol

Answer 3

Reagent: NaOH(aq)
Conditions: H2O, heat, reflux
Mechanism: nucleophilic substitution
Side product: hydrogen halide

Question 4

Halogen test

Answer 4

1. Add NaOH(aq)
2. neutralise with HNO3
3. Add AgNO3
4. precipitate is added

Question 5

AgCl (s)

Answer 5

white ppt

Question 6

AgBr

Answer 6

cream ppt

Question 7

AgI

Answer 7

yellow ppt

Question 8

Haloalkane rates test

Answer 8

1. Add H20 and AgNO3(aq)
2. heat in water bath 60°C
3. add ethanol
4. monitor rate of precipitate appearing

Question 9

Bond strength of C-X bonds

Answer 9

1. bond enthalpy decreases down the group
2. less energy to overcome
3. reacts fastest
4. quickest rate of hydrolysis

Question 10

Mechanism of chlorine radicals

Answer 10

CF2Cl2 → CF2Cl* + *Cl
*Cl + O3 → *ClO + O2
*ClO + O → *Cl + O2

Question 11

Disadvantage of chlorofluorocarbons

Answer 11

1. form chlorine radicals
2. reacts with ozone
3. decreases absorption of UV from sun
4. increased global warming

Question 12

Advantage of HCFC

Answer 12

1. less stable
2. more likely to break down before reaching ozone

Question 13

Use of CFC

Answer 13

1. air conditioning
2. refrigeration
3. aerosols

Question 14

CFC benefits

Answer 14

1. liquid
2. readily evaporated
3. non-flammable
4. unreactive
5. non-toxic

Question 15

Mechanism of NO radicals

Answer 15

*NO + O3 → *NO2 + O2
*NO2 + O → *NO + O2

Question 16

Net reaction of ozone layer destruction

Answer 16

O3 + O -> 2O2
-NO and Cl act as catalyst

Question 17

Production of NO

Answer 17

1. thunderstorms
2. combustion engines
3. aircraft exhaust gases

Question 18

Still concerns about ozone depletion

Answer 18

1. CFCs take many years to reach ozone layer
2. CFCs still being used
3. other ozone depleting substances

Question 19

Formation of NO

Answer 19

N2(g) + O2(g) -> 2NO(g)

Question 20

Haloalkane to amine

Answer 20

Reagents: NH3(g)
Conditions: ethanol
Side products: HX
Mechanism: nucleophilic substitution

Question 21

Haloalkane to ammonium salt

Answer 21

Reagents: excess NH3(g)

Question 22

Haloalkane to nitrile

Answer 22

Reagent: NaCN
Conditions: ethanol
Mechanism: nucleophilic substitution

Question 23

Haloalkane to nitrile

Answer 23

Reagent: NaCN
Conditions: ethanol
Mechanism: electrophilic substitution