Haloalkanes

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  • Created by: ElishaG
  • Created on: 05-04-17 20:10
What is hydrolysis?
The breaking of a bond by its reaction with water.
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What is a nucleophile?
A species attracted to an electron deficient centre where is donates a pair of electrons to form a new covalent bond.
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What is electronegativity?
The ability for an atom to attract the bonding pair of electrons in a covalent bond.
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What is a homologous series?
A series of organic compounds having the same functional group differing by CH2.
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What is a functional group?
A group of atoms responsible for the characteristic reactions of a compound.
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What is saturated?
Containing single bonds only.
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What is unsaturated?
Containing at least one carbon to carbon double bond.
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What is a 'curly arrow'?
Indicates the movement of an electron pair shows formation or breaking of a covalent bond.
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What is a radical?
A species with an unpaired electron?
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What is homolytic fission?
The breaking of a covalent bond where the electron pair is split equally, forming 2 radicals.
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What is heterolytic fission?
The breaking of a covalent bond where the electron pair isn't split equally, forming a cation and anion.
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What is atom economy?
(Molecular mass of desired product/molecular mass of sum of products)X100
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What is bond enthalpy?
The average enthalpy change that takes place when breaking 1 mol of a given type of bond in the molecules of a gaseous species.
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What is bond polarity?
The polarity that arises in a covalent bond due to electronegativities.
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What is a substitution reaction?
A chemical reaction in which an atom in a reactant molecule is replaced with a different atom.
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What is electron deficient?
An atom with a slight positive charge due to a covalent bond with a more electronegative atom
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What is reflux?
The continuous boiling and condensing of a reaction mixture to ensure the reaction takes place but stops the flask contents boiling dry.
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What is volatility?
The ease with which liquid turns into a gas.
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What is the prefix for the halogens when naming haloalkanes?
1)Fluorine= Fluoro.2)Chlorine= Chloro.3)Bromine= Bromo.4)Iodine= Iodo.
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How can you determine whether a haloalkane is primary, secondary or tertiary?
1)By looking at the number of carbons attached to the carbon of interest.2)1 carbon= primary. 2 Carbons= Secondary. 3 Carbons= tertiary.
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Describe nucleophilic substitution.
1)Heterolytic fission occurs, the partially negative halogen takes both electrons from carbon.2) delta -ve nucleophile bonds with delta +ive carbon.3)Halogen ion left on its own.
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Where are the curly arrows drawn in this reaction?
1)From C bond to halogen.2)From nucleophile to carbon.
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What is the reagent, solvent and conditions for hydrolysis of primary alkanes?
1)Ethanolic silver nitrate solution.2)Ethanol.3)Warm 40 degrees.
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Why is ehtanolic silver nitrate used?
It is the source of the OH- ion.
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Why is ethanol used as a solvent?
The haloalkane is insoluble in water, but soluble in ethanol allowing the aq silver nitrate to mix.
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What are the two reactions in hydrolysis?
1)Nucleophilic substitution.2)Precipitate formation.
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Describe the first reaction.
1)Haloalkane reacts with water from the silver nitrate solution.2)Forms an alcohol and acid.
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Describe the second reaction.
The halide ion reacts with silver nitrate to form a precipitate.
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What is the purpose of the silver nitrate?
1)The mass of precipitate formed in given time= measure rate of reaction.2)Or time taken for precipitation to be observed= measure rate of reaction.
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Does the rate of hydrolysis increase or decrease from fluro(haloalkane) to iodo (haloalkane)?
Increase
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What colour precipitate does chloroalkane form?
White.
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What colour precipitate does bromoalkane form?
Cream.
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What colour precipitate does Iodoalkane form?
Yellow.
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Which silver halide precipitate would form first?
1)Silver iodide.2)C-I bond is longest,weakest and easiest to break.
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Which silver halide precipitate would form last?
1)Silver chloride.2)C-Cl bond is shortest, strongest and most difficult to break.
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What are properties of haloalkanes?
1)Non-toxic.2)Unreactive.3)Low boiling points (high volatility).
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What are 2 uses of haloalkanes?
1)Polymers.2)Chloroflurocarbons.
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Describe polymers.
1)E.g. PVC used for toys,drainpipes,plastic window frames, packaging.2)Teflon used for non-stick pans, C-F bonds strong and resistant to heat.
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Describe chloroflurocarbons.
1)aka CFC's compounds containing chlorine and fluorine.2)Refrigerants,aerosols, air conditioning.3)Low reactivity,high volatility, non-toxic.
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What does the ozone layer do?
1)made up of O3.2)Absorbs harmful UV radiation from sun.
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What is the problem with CFC's?
1)Become unstable when they reach the stratosphere.2)In presence of UV light produces chlorine free radicals.
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What are alternative methods to CFC's?
1)HCFC's- less stable and break down before reaching stratosphere, still produce chlorine radicals.2)HFC's break down in atmosphere, don't contain chlorine, may have other harmful effects.3)Thinking about using hydrocarbons instead.
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Describe nitrogen oxide.
1)Created during thunderstorms and in internal combustion engines.2)Most of gas is removed in atmosphere.3)NO can react with moisture to form nitric acid-acid rain.4)Some moves to stratosphere and attacks ozone layer.
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Why doesn't nitrogen oxide have an initiation step?
Because it already has an unpaired electron.
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Other cards in this set

Card 2

Front

What is a nucleophile?

Back

A species attracted to an electron deficient centre where is donates a pair of electrons to form a new covalent bond.

Card 3

Front

What is electronegativity?

Back

Preview of the front of card 3

Card 4

Front

What is a homologous series?

Back

Preview of the front of card 4

Card 5

Front

What is a functional group?

Back

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