Hydrocarbons and Plastics

Question 1

what is a homologous series

Answer 1

a homologous series is a series of molecules with the same general formula and similar chemical properties

Question 2

What is a hydrocarbon?

Answer 2

A hydrocarbon is a molecule that contains only carbon and hydrogen atoms.

Question 3

what are alkanes

Answer 3

alkanes are a homologous series of hydrocarbons with single carbon to carbon bonds.

Question 4

what is the general formula for the alkanes

Answer 4

CnH2n+2

Question 5

what is an isomer

Answer 5

Isomers have the same molecular formula but different structural formula-same number of atoms arranged in different ways.

Question 6

what is a cycloalkane

Answer 6

a cycloalkane is another hydocarbon family. The carbon atoms are all joined together to form a ring.

Question 7

what is the general formula for a cycloalkane

Answer 7

CnH2n

Question 8

What are the alkenes

Answer 8

the alkenes are another hydrocarbon family. They must posses a carbon to carbon double bond. The name ends in ene

Question 9

why cant you have a branch on ethene or propene

Answer 9

it would just be a continuation of the chain

Question 10

why dont you call ethene “eth-1-ene” or propene “prop-1-ene”

Answer 10

because theres only 1 position for the double bond

Question 11

what are the physical properties of hydrocarbons?

Answer 11

at room temperature they are usually clear liquids.
they are highly flammable
they smell like petrol
a use of them is fuels

Question 12

explain the term saturated

Answer 12

it means all their carbon to carbon bonds are single bonds

Question 13

explain the term unsaturated

Answer 13

it means it contains a carbon to carbon double bond - it will decolourise bromine solution

Question 14

what happens as the chain length increases

Answer 14

the melting and boiling point increase - the intermolecular forces become stronger.

Question 15

what will happen when you add bromine solution (halogen) to an unsaturated hydrocarbon

Answer 15

the unsaturated hydrocarbon (alkene) will undergo an addition reaction with the bromine - the bromine would rapidly decolourise

Question 16

what hydrocarbons are saturated and unsaturated

Answer 16

saturated - alkane, cycloalkane

unsaturated - alkene

Question 17

when a hydrocarbon is burned what will the products be

Answer 17

water (H20) + carbon dioxide (CO2) (if there isnt a plentiful supply of oxygen it will produce carbon monoxide)

Question 18

what is the hydrocarbon reacting with when it is burned ( combustion)

Answer 18

oxygen

Question 19

what is an addition reaction

Answer 19

when a chemical is added across the double bond of an alkene. the unsaturated molecule becomes saturated.

Question 20

what is the name of an addition reaction with water

Answer 20

hydration

Question 21

what is the name of a addition reaction involving hydrogen

Answer 21

hydrogenation reaction

Question 22

what is the name of an addition reaction involving a halogen

Answer 22

halogenation

Question 23

what is a plastic

Answer 23

a plastic is a substance which can be shaped or moulded into solid objects
they are synthetic (made by scientists)

Question 24

what are plastics usually made from

Answer 24

plastic are usually made from chemicals found in crude oil-mostly alkenes

Question 25

what can plastics be used for

Answer 25

they can be used as synthetic fibers such as nylon and gore-tex

Question 26

what is meant by a synthetic fibre

Answer 26

fibre made from plastic/polymer

Question 27

what is meant by thermoplastic and thermosetting

Answer 27

thermoplastic means it softens under heat, thermosetting means it hardens under heat.

Question 28

describe how the properties of plastics relate to their uses

Answer 28

hardened plastics for milk cartons a flexible plastic for cling film soft plastic for carrier bags thermosetting plastics for kettles/pot handles

Question 29

what is meant by biodegradable

Answer 29

biodegradable means something can rot naturally. plastics are not biodegradable

Question 30

describe what happens when a plastic is recycled

Answer 30

the plastic is broken apart and shredded into flakes or pellets and cleand. the flaked or pellets are then sent to manufacturers of plastic goods

Question 31

what are some examples of what recycled plastics can be converted to

Answer 31

t-shirts, plastic lumber, toys, compost bins, rulers

Question 32

what happends when plastics are burned

Answer 32

they release toxic gasses. (carbon monoxide) PVC releases hydrogen chloride HCN releases hydrogen cyanide(if its plolyurethane)

Question 33

what are plastics made from?

Answer 33

a monomer | the plastic is called the polymer and it takes its name from the monomer

Question 34

what is addition polymerisation

Answer 34

it is the process to make polymers from monomers | Polymerisation is when the double bond in alkenes opens up to allow another alkene to join

Question 35

why do the monomers need to have a carbon to carbon double bond

Answer 35

you need a carbon to carbon double bonds for an addition reaction to take place (addition polymerisation)