Chemistry Topic 7//Alkenes//Addition Polymers Flashcards

1
Q

What are Alkenes

A

hydrocarbons which have a C=C double bond between 2 carbon atoms

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2
Q

Why are alkenes unsaturated

A

Because alkenes have 2 fewer hydrogens than alkanes but containing same number of carbon atoms

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3
Q

Why are alkenes reactive

A

The C=C bond can open up to make a single bond allowing 2 carbon atoms to react with other atoms

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4
Q

What is the general formula for alkenes

A

CnH2n

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5
Q

What are the 4 alkenes and there formula

A

Ethene- C2H4
Propene- C3H6
Butene- C4H8
Pentene- C5H10

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6
Q

Describe how alkenes react when they combust in oxygen

A

In a large amount of oxygen, alkenes combust completely to produce water and carbon dioxide and a lot of energy

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7
Q

Describe how alkenes react when they combust in air

A

When you burn alkenes in air, they tend to undergo incomplete combustion to produce carbon dioxide, water, carbon and carbon monoxide (poisonous gas)

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8
Q

What does an incomplete combustion result in and what happens to the energy released

A

Incomplete combustion results in a smoky yellow flame and there is less energy being released

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9
Q

What are the three types of addition reactions with

A

Water
Hydrogen
Halogens

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10
Q

Describe what happens when an alkene reacts with hydrogen

A

Hydrogen can react with the double bonded carbons in the presence of catalyst to open up the double bonds and form the saturated alkane

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11
Q

Describe what happens when an alkene reacts with halogens

A

Halogens react with the double bonded carbons to open up the double bonds and form saturated alkanes

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12
Q

Describe what happens when orange bromine water is added to an ALKANE and ALKENE

A

When orange bromine water is added to an ALKANE, no reaction happens because they do not have a double carbon bond.
When orange bromine water is added to an ALKENE, the bromine will add across the double carbon bond making colourless dibro-compound so bromine is decolourised

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13
Q

What is a polymer

A

Made up of long molecules formed when lots of small molecules called monomers join together which is called polymerisation

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14
Q

What are addition polymers made from

A

Unsaturated monomers

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15
Q

what do the monomers in addition polymerisation contain

A

They contain double carbon bonds C=C

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16
Q

Describe addition polymerisation

A

Lots of unsaturated monomer molecules called alkenes react with pressure and a catalyst which opens up the double bond and forms a polymer