topic 9 Flashcards by Helen Ross

Define hydrocarbon

a molecule consisting of hydrogen and carbon only

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what is a homologous series?

A family of compounds with similar chemical properties, a trend in physical properties, that differ by a CH2 group

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What is a saturated hydrocarbon?

A hydrocarbon containing only single-bonded carbon atoms.

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What is an unsaturated hydrocarbon?

a hydrocarbon that contains at least one double or triple carbon bond.

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What is the sentence that helps to remember how many carbon atoms are present in a molecule?

Monkeys (Meth- = 1)
Eat (Eth- = 2)
Peanut (Prop- = 3)
Butter (But- = 4)

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What is the general formula for an alkane?

CnH2n+2

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What is the general formula for an alkene?

CnH2n

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When combustion of a fuel occurs, it means that the fuel has reacted with _________.

oxygen

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What is the difference between complete and incomplete combustion?

In complete combustion, CO2 is always formed as there is enough oxygen to fully react. Incomplete combustion produces either CO or just C.

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The more chains in a hydrocarbon, the ________ the boiling point.

higher

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The more chains in a hydrocarbon, the _______ volatile it is

less

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The more chains in a hydrocarbon, the ________ viscous it is.

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The more chains in a hydrocarbon, the ________ ignitable it is.

less

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What is the test for unsaturated hydrocarbons?

Bromine water. If it turns colourless, unsaturated hydrocarbons are present.

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Why are alkanes saturated hydrocarbons?

Because they have no carbon double bonds

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How does the bromine water test work?

The C=C double bond in alkenes reacts with the Bromine to form colourless products. Alkanes do not react because they do not contain double bonds

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What does the complete combustion of alkanes and alkenes involve?

oxidation of he hydrocarbons to produce CO2 and H2O

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Define polymer

A long chain molecule made from lots of small molecules joined together

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Define monomer

Small molecule that joins with other monomers to create polymers

Define polymerisation

The formation of polymers by joining monomers together

How can ethene molecule combine in polymerisation?

They lose their carbon double bond in order for the carbon to bond with another ethene

What does the polymerisation of ethene form?

Polyethene

Give some properties and uses of polyethene

Properties:
Flexible, cheap

Uses:
Plastic bags and bottles

Give some properties and uses of polychloroethene (PVC)

Properties:
tough, cheap

Uses: window frames, water pipes

Give some properties and uses of polytetrafluoroethene (PTFE, commonly teflon)

Properties: unreactive, tough Uses: non stick pans, waterproof clothing

What is the problem with the production of polymers?

Plastics are made from crude oil (finite)

What is the problem with the disposal of polymers?

Most polymers are not biodegradable, causing persistence in landfill sites

List the pros and cons of recycling polymers

Pros: - reduces amount of polymers in landfill - reduces toxic emissions from burning polymers - uses less energy than making new polymers - reduces amount of crude oil needed to make more plastics - saves money and creates jobs Cons: - Polymers must be separated by type before they can be melted (difficult and expensive) - can be more expensive than making new polymers - if polymers are mixed, the quality of the product may be reduced - polymers can get weaker over time so can only be recycled a finite amount of times - melting down polymers can release toxic gases

Define condensation polymerisation

the formation of polymers using condensation reactions with monomers that contain multiple functional groups

Why are polyesters condensation polymers?

Because each time an ester link is formed, a molecule of water is lost (which only occurs in condensation polymerisation)

How is a polyester formed?

dialcohol (diol) + dicarboxylic acid -> polyester + water

What is an ester link and what does it result in when formed?

Why must the test for any ion must be unique

you would never be able to know which specific ion it was if more than one ion gave the same result

Lithium ion flame test

red

Sodium ion flame test

yellow

Potassium ion flame test

lilac

Calcium ion flame test

orange-red

Copper ion flame test

blue-green

Describe the flame test

hold a sample you wish to test on a wire in a roaring bunsen burner flame and observe the flame colour

Describe the chemical test for ammonia

● Makes damp red litmus paper turn blue ● It also forms a white smoke of ammonium chloride when hydrogen chloride gas, from concentrated hydrochloric acid, is held near it

Aluminium ion as a solution test (using sodium hydroxide solution)

White precipitate (dissolves when excess NaOH is added)

Calcium ion as a solution test (using sodium hydroxide solution)

White precipitate

Copper ion as a solution test (using sodium hydroxide solution)

Blue precipitate

Iron (II) ion as a solution test (using sodium hydroxide solution)

Green precipitate

Iron (III) as a solution test (using sodium hydroxide solution)

Brown precipitate

Ammonium ion as a solution test (using sodium hydroxide solution)

○ Pungent-smelling gas is produced ○ This gas produced turns damp red litmus paper blue