Haloalkanes Flashcards

1
Q

Suggest two reasons why there is still concern about ozone depletion. (2)

A
  • CFCs take many years to reach ozone layer;
  • CFCs are still being used;
  • there are other ozone depleting substances (NO, HFCs);
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2
Q

Suggest a property that made CF3Cl suitable as a propellant in an aerosol.

A

volatile, low BP, unreactive, non-flammable

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3
Q

homolytic fission

A

covalent bond breaks

each bonded atom retains 1 electron/ shared equally

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4
Q

Suggest which bond is most likely to be broken when CF3Cl is exposed to
ultraviolet radiation. Explain your answer.

A

C-Cl

weakest bond

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5
Q

Identify the two free radicals most likely to be formed when CF3Cl is exposed to
ultraviolet radiation.

A

Cl•

CF3•

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6
Q

Uses of CFCs

A
  • (propellant in) aerosols because it is volatile/ unreactive/ non-toxic/ easily compressed
  • blowing polystyrene because it is unreactive
  • dry cleaning because it is a good solvent for organic material
  • degreasing agent because it is a good solvent for organic material
  • fire extinguishers because it is non-flammable
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7
Q

rate of hydrolysis reaction - why was hot water bath used?

A

providing kinetic energy so more successful collisions to speed up ror

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8
Q

rate of hydrolysis reaction - explain the 2 roles of HNO3 in the reaction

A
  • provides nucleophile

- provides indicator

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9
Q

rate of hydrolysis reaction - explain purpose of ethanol in reaction

A

cosolvent as haloalkanes insoluble in water

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10
Q

rate of hydrolysis reaction - what reagents do you need?

A

-heat AgNO3
- ethanol
- 1-bromo,1-chloroand 1-iodobutane (3 drops added to ethanol)
iodo forms precip -> bromo -> chloro

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11
Q

rate of hydrolysis reaction - what is the equation of the hydrolysis of a haloethane?

A

CH3CH2X + H2O -> CH3CH2OH + HX

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12
Q

rate of hydrolysis reaction - equation for halogen reacting with silver ion

A

Ag+ (aq) + X-(aq) -> AgX (s)

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13
Q

rate of hydrolysis reaction - why does iodine react that fastest?

A

C-I bond is the weakest

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14
Q

How is ozone formed? (eq)

A

O2 —->(UV) 2O•

O2 + O• —> O3

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15
Q

How is ozone broken down? (eq)

A

O3 —–> (UV) O2 + O•

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16
Q

Equation for photodissociation of CFCs in the stratosphere

A

produces Cl radicals

CClF3 ——> (UV) CF3• + Cl•

17
Q

Show how Cl• cause the breakdown of the ozone layer (2 stages +overall equation)

A

Cl• + O3 —> ClO• + O2
ClO• + O3 —> Cl• + 2O2
————————————
2O3 ——–> (Cl•) 3O2

18
Q

the Cl• acts as a …. in the breakdown of the ozone

A

catalyst