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Science gcse > C22 - C24 > Flashcards

C22 - C24 Flashcards

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1
Q

What are alkanes ?
Describe alkanes in terms of carbon bonding
First 4 alkanes

A

Alkane is a hydrocarbon - form a homologous series
General formula Cn H2n+2
Carbon single bond - makes it saturated

Methane - CH4
Ethane - C2 H6
Propane - C3 H8
Butane - C4 H10

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2
Q

What are alkenes ?
Describe alkenes in terms of carbon bonding
First 4 alkenes

A

Alkene is a hydrocarbon - Form a homologous series
General formula Cn H2n
C=C - Carbon double bond makes it unsaturated

Ethene - C2 H4
Propene - C3 H6
Butene - C4 H8

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3
Q

Addition reaction of ethene with bromine

A

Ethene + Bromine = Dibromoethane

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4
Q

What is the test to see alkenes and alkanes

A

Alkene will turn brown bromine water colourless

Alkane will not react and bromine water will stay brown

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5
Q

What is the combustion reaction of alkanes and alkenes

A

Hydrocarbon + oxygen = Carbon dioxide + water

This is oxidation of the hydrocarbon

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6
Q

What is a polymer ?

A

Substance of high relative formula mass made up of small repeating units

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7
Q

How do ethene molecules combine and what does it form ?

A

Ethene molecules combine through a polymerisation reaction to form poly(ethene)

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8
Q

What are the uses of polymers and why are they used in this way
(4 polymers)

A

Poly(ethene) - Flexible , cheap and can be made into thin films - Used in carrier bags , food wrappings and shampoo bottles

Poly(propene) - Flexible , strong and resists shattering - Used in buckets , bowls , ropes , carpets

Poly(chloroethene) - Tough , electrical insulator , can be made hard or flexible - Used in electrical wires , windows , gutters and pipes

Poly(tetrafluoroethene) - slippery , chemically unreactive - used in non stick coating for pans and containers for laboratory substances

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9
Q

What are some problems of polymers

A

They are non biodegradable so they end up in landfills

We can burn these polymers but it an be bad for environment as carbon dioxide is released into the atmosphere

We can recycle polymers , but they have to be separated from each other first , this can be expensive and difficult to do

made from finite resources

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10
Q

Describe the polymer DNA

A

Made from 4 monomers - the nucleotides
Double helix structure
hydrogen bonds

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11
Q

Monomer of starch

A

Sugars

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12
Q

Monomer of protein

A

Amino acids

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13
Q

Describe what alcohols are

What are the first 4 alcohols

A

Alcohols form a homologous series - OH
General formula of : Cn H2n+1 OH

Methanol - CH3 OH
Ethanol - C2H5OH
Propanol - C3H7OH
Butanol - C4H9OH

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14
Q

Describe what carboxylic acids are

What are the first 4 carboxylic acids

A

Form a homologous series - COOH
General formula : Cn H2n+1 COOH

Methanoic acid - H COOH
Ethanoic acid - CH3 COOH
Propanoic acid - C2H5 COOH
Butanoic acid - C3H7 COOH

Carboxylic acids are weak acids

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15
Q

Oxidisation of ethanol ( not combustion)

A

Ethanol + oxygen = Ethanoic acid + water

C2H5 OH + O2 = CH3 COOH +H2O

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16
Q

How do we produce ethanol by fermentation

A

Firstly sugars are dissolved in water and then yeast is added - yeast is added because yeast has the enzymes needed for fermentation

Then we put an airlock to the container because anaerobic conditions are needed for fermentation

We then leave the air tight container in a temperature of 25 - 35 degrees

17
Q

How do we purify the ethanol made from fermentation

A

Firstly we use filtration to remove any solids like the yeast cells

Fractional distillation is then used to separate the ethanol from the filtrate , this works because ethanol has a unique boiling point ,ethanol evaporated more readily compared to water

18
Q

What is addition polymerisation ?

A

When alkene monomers join together to form a polymer - same monomers

Only 1 product formed

19
Q

What is condensation polymerisation ?

A

We start with monomers
2 different reactivity groups - COOH , C= C , OH
Another product like water is formed

Science gcse (25 decks)

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