compounds in which a halogen has replaced a hydrogen atom in an alkane chain
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what is the general formula for halogenoalkanes ?
CnH2n+1X
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why are halogenoalkanes fairly reactive ?
because they contain a polar carbon- halogen bond due to the difference in electronegativity of carbom and halogen.
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explain how reactivity changes across the halogens
as you go down the group reactivity decreases as electronegativity decreases.
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why does a polar bond in halogenoalkanescause it to react ?
bond means that the electron pair is more attracted to the halogen atom , this causes the carbon atom to become electron deficient attracting nucleophiles causing a substitution reaction
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what happens when halogenoalkanes react with hot hydroxide ions ?
a nuceophilic substitution reaction occurs producing an alcohol
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define reflux
the continuous boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry
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define nucleophilic substitution ?
a substitution reaction in which a nucleophile is attracted to an electron deficient atom where it donates a pair of electrons to form a new covalent bond
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how can you work out the rate of hydrolysis for different halogenoalkanes?
calculate 1 divided b the time taken for precipitate of each halogenoalkane to form
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what two factors affect the rate of hydrolysis ?
polarity and bond enthalpies
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how does polarity affect rate of hydrolysis of halogenoalkanes ?
the more polar the bond is the more attracted a nucleophile is to the carbon atom resulting in a fast rate
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how does bond enthalpy affect rate of hydrolysis of halogenoalkanes ?
weak bonds mean they are easier to break speeding up the rate of reaction
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name two uses of PVC
drainpipes and children's toys
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what is PVC made from ?
the polymerisation of chloroethene
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why are CFC's bad for the environment ?
because when they reach the stratosphere , ultra violet radiation breaks them down to form chlorine radicals which then catalyse the breakdown of the ozone layer
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what is percentage yield ?
actual amount in mol of product , divided by the theoretical amount in mol of product times 100
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what is a limiting reagent ?
the substance that runs out first in a chemical reaction
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hat do we do with by products ?
may be sold and waste
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What are the problems with by products ?
they are costly to dispose of and poses environmental problems
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define atom economy
(molecular mass of desired product) divided by ( sum of molecular masses f all the products) X 100
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how can atom economy benefit society ?
using processes with a higher atom economy reduces waste produced making it cheaper and more environmentally friendly
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what is the atom economy of a addition reaction ?
100%
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how is atom economy and percentage yield different ?
percentage yield tells us the efficiency of converting reactants into products, atom economy tells you the proportion of desired products compared with all products formed
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Other cards in this set
Card 2
Front
what is the general formula for halogenoalkanes ?
Back
CnH2n+1X
Card 3
Front
why are halogenoalkanes fairly reactive ?
Back
Card 4
Front
explain how reactivity changes across the halogens
Back
Card 5
Front
why does a polar bond in halogenoalkanescause it to react ?
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