Ozone Story - Halogen Reactions Flashcards

1
Q

When will an alkane react with a halogen?

A

in the prescence of light

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2
Q

What are rates of reaction measured in?

A

mol dm-3 s-1

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3
Q

What are the 4 ways of measuring the rate of a reaction?

A

volume of gas produved

change in mass

change in pH

change of precipitate or colour

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4
Q

What is the Bolzmann distribution curve?

A
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5
Q

What is Ea?

A

activation enthalpy - the minimum amount of energy that reactants must have for a reaction to occur

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6
Q

If the temperature increases, what happens to the curve on a Bolzmann distribution curve?

A

the peak is lower and shifts to the right

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7
Q

What happens to the Ea on a Bolzmann curve if a catalyst is present?

A

it shifts to the left

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8
Q

What can rate of reaction be affected by?

A

temperature

concentration / pressure of reactants

intensity of radiation

particle size (in solids)

presence of a catalyst

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9
Q

What does CFC stand for?

A

chlorofluorocarbon

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10
Q

What are the properties of CFC in the troposphere?

A

non-toxic

non-flammable

very stable

very strong bonds

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11
Q

How can the overall result from a chain reaction be found?

A

add together the propogation steps

cancel any molecules that appear on both sides

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12
Q

What is the spectrum of bond strengths?

A

non-polar

polar

ionic

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13
Q

What is a pd-pd force?

A

permanent dipole - permanent dipole attraction

when the polar part of a molecule attracts the opposite polarity in another

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14
Q

What determines the strength of a polar bond?

A

How electronegative the elements are - the bigger the gap in electronegativity the more polar the bond

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15
Q

Why are symmetrical molecules not polar?

A

the forces cancel each other out

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16
Q

What are the features of an id-id force?

A

present in all molecules

weak force

depends on number of electrons present

branches reduces the effect

17
Q

What are the features of pd forces?

A

can induce a pd-id force

forms pd-pd forces

only present in polar molecules

molecules have a higher melting/boiling point

stronger than id-id

18
Q

What type of bond is stronger than pd-pd interaction?

A

hydrogen bonding

19
Q

When will an id-id force be stronger than a pd-pd force?

A

if the molecules in the id-id force have significantly more electrons than the pd-pd molecules

20
Q

What is a nucleophile?

A

something that can donate a pair of electrons to form a covalent bond

21
Q

What type of molecule can be a nucleophile?

A

must have a non bonding pair of electrons

can be anions but not always

22
Q

How are nucleophillic molecules usually represented?

A

:nuc-

23
Q

What are the conditions for nucleophilic subsitution?

A

RTP

24
Q

What is a disadvantage of nucleophilic substitution?

A

the atom economy wonโ€™t be 100%

25
Q

What happens during nucleophilic substitution with simple ions?

A

nucleophile is attracted to the ๐›ฟ+ section of the molecule

this causes the on the ๐›ฟ+ section to move to the ๐›ฟ- section

simple ion bonds to the ๐›ฟ+ section and ๐›ฟ- section is given off as its own molecule

26
Q

What are the reaction conditions for the production of HBr?

A

mix NaBr with phosphoric or sulfuric acid

heat under reflux

27
Q

How can a haloalkane be converted into an alcohol?

A

nucleophilic substitution using water

28
Q

How can an alcohol be converted into a haloalkane?

A

by adding a hydrogen halide

29
Q

What are the 2 ways that haloalkanes can be produced?

A

adding a hydrogen halide to an alcohol

adding a hydrogen halide to an alkene

30
Q

How can a haloalkane be converted into an amine?

A

nucleophilic substitution using NH3

31
Q

What happens to the bond enthalpies of halogens as you go down the group?

A

the bond enthalpies get less exothermic

32
Q

What are the reaction conditions for the nucleophilic substitution of a haloalkane using hydroxide ions?

A

use warm, aqueous sodium hydroxide

heat under reflux

33
Q

What are the reaction conditions for the nucleophilic substitution of a haloalkane using ammonia?

A

warm the haloalkane with excess ethanolic ammonia (ammonia dissolved in ethanol)

heat under reflux

34
Q

What are the reaction conditions for reacting haloalkanes with water?

A

add ethanol

add silver nitrate to see results

35
Q

What is most important in a reaction - polarity or bond enthalpy?

A

bond enthalpy

36
Q

What is the method for heating under reflux?

A

heat reagents in a round bottomed flask with a condenser vertically attached to it, so that evaporated products will condense and drip back down into the flask

37
Q
A