Ch 8 - Organic Chemistry 1 Flashcards

Question

Complete combustion releases **...** and only produces two **...**. When there's **...** and combustion is complete, the gas burns with a **...** flame.

Answer 1

Complete combustion releases **lots of energy** and only produces two **harmless waste products (carbon dioxide and water)**. When there's **plenty of oxygen** and combustion is complete, the gas burns with a **clear blue** flame.

Answer 2

carbon dioxide and water vapour are one of the main greenhouse gases it rises into the atmosphere but traps all the air so it is re-emmited back out again one effect of global warming is the melting of ice caps which causes flooding

Answer 3

methane + oxygen → carbon dioxide + water CH₄ + 2O₂ → CO₂ + 2H₂O

Answer 4

when there isn' enough oxygen

Answer 5

no carbon monoxide or carbon (soot) is produced instead of carbon dioxide

Answer 6

colourless odourless very poisonous

Answer 7

it combines with haemoglobin (the molecule that carries oxygen in the blood stream), preventing it from carrying oxygen you are made ill, or even die, because not enough oxygen gets to the cells in your body

Answer 8

a substitution reaction a hydrogen atom from the alkane is substituted (replaced) by chlorine or bromine

Answer 9

A mixture of bromine and methane is the colour **brown** because **of the presence of the bromine**. If exposed to U.V. light, such as sunlight, **bromomethane and hydrogen bromide gas is formed** and **the colour is lost**

Answer 10

Alkanes are **hydrocarbons** but are different to alkanes because they have **C=C carbon double** bonds

Answer 11

smoky yellow

Answer 12

methane + oxygen → carbon monoxide + water 2CH_4(g)+ 3O_2(g)→ 2CO_(g)+ 4H₂O_(l)

Answer 13

haloalkanes

Answer 14

Halogens, such as chlorine and bromine, react with alkanes in the presence of **ultra-violet light** (e.g.sunlight). This is called **photolysis**

Answer 15

Halogens have **weak** bonds that are **easy** to break by U.V. light

Answer 16

No, only alkanes

Answer 17

Alkenes undergo **addition** reactions part of the double bond breaks and the electrons are used to join other atoms onto the two carbon atoms

Answer 18

the reaction between bromine and alkenes is often used when you shake an alkene with orange bromine solution ('bromine water'), the solution becomes colourless this is because the bromine molecules, which are orange, are reacting with the alkened to make dibromoalkane, which is colourless

Answer 19

unsaturated this is because they contian a double carbon bond

Answer 20

from cracking alkanes

Answer 21

the process where a long chain alkane is broken down from larger molecules into smaller molecules; more useful alkanes and alkenes

Answer 22

ethene: C₂H₄ propene: C₃H₆ butene: C₄H₈

Answer 23

The first four alkenes are **gas** at room temperature. All the other ones you are likely to come across at GCSE are **liquids**. Alkenes are **solid** around C₁₇H₃₄

Answer 24

carbon dioxide and water

Answer 25

haloalkenes

Answer 26

For bromine to add to alkenes, heat or a catalyst **isn't** needed

Answer 27

a homologous series

Answer 28

an -OH group e.g. ethanol is C₂H₅OH

Answer 29

they are covalently bonded onto a carbon chain

Answer 30

ethanol - C₂H₅OH

Answer 31

C_nH_2n+1OH

Answer 32

The best way to make ethanol often depends on **what resource is most easily available - oil or sugar**

Answer 33

fermentation hydration of ethene

Answer 34

yeast is not a chemical but a microorganism N.B. do not write it as a molecule in a formula but instead out it over the arrow

Answer 35

yeast is added to a sugar or starch solution and left for several days in the warm (30-40^oC) with the absence of air (anaerobic conditions) enzymes (biological catalysts) in the yeast convert the sugar into ethanol and carbon dioxide

Answer 36

ordinary sugar (sucrose) is split into two smaller sugars: glucose and fructose glucose and fructose have the same molecular fomulae, but are differet structures (they are isomers) enzymes in the yeast convert these sugars into ethanol and water * C₁₂H₂₂O_{11 (aq)}**(sucrose)** + H₂O _(l)**(water)** → C₆H₁₂O₆_(aq)**(glucose)** + C₆H₁₂O₆_(aq) **(fructose)** * C₆H₁₂O₆_(aq)**(glucose)** → 2C₂H₅OH _(aq) **(zymase) +** 2CO_{2 (g)}**(carbon dioxide)**

Answer 37

no, it is impossible yeast is killed by +15% of alcohol in the mixture instead, the alcohol is purified by fractional distillation - this takes advantage of the difference in boiling point between ethanol (78^oC) and water (100^oC) the liquid distilling over 78^oC is 96% pure ethanol and the rest is water - it is impossible to remove this last 4& of water by simple distillation

Answer 38

renewable resources sugar beet or sugar cane, corn and other starchy materials

Answer 39

a batch process everything is mixed together in a reaction vessel, then left for a several days that batch is removed and a new reaction is set up this is inefficient

Answer 40

very slow, taking several days for each batch

Answer 41

very impure - needs further processing not very concentrated - needs to be distilled to increase its strength (as in whiskey distilleries)

Answer 42

gentle temperatures (about 30^oC) simple, cheap equipment ordinary pressures

Answer 43

yes sugar (sugar cane) is grown as a major crops in several parts of the world, including poorer countries

Answer 44

The alcohol in beer and wine etc... is made by **fermentation**

Answer 45

by cracking crude oil

Answer 46

reacting ethene with steam

Answer 47

ethanol vapour is passed ober a hot catalyst of aluminium oxide, Al₂O₃ the catalyst provides a large surface area for this reaction

Answer 48

ethene and steam

Answer 49

60 - 70 atmospheres

Answer 50

phsophoric acid - H₃PO₄

Answer 51

only a small proportion of ethene reatcs the unreacted ethene is recyled through the process

Answer 52

it is condensced as a liquid

Answer 53

finite resources (ethene from oil) once all the oil has been used up there won't be any more

Answer 54

a continuous flow process a stream of reactants is constantly passed over the catalyst this is more efficient than a batch process

Answer 55

1. The oil is heated until most of it has turned into gas. The gases enter a fractionalating column (and the liquit bit, bitumen, is drained off at the bottom) 2. In the column there's a temperature gradient (it's hot at the bottom and gets gradually cooler as you as you go up). When the substances that make up crude oil reach the part of the column where the temperature is lower than their boiling point they condense (turn back into a liquid) 3. The longer hydrocarbons have high boiling points. They condense and drain out of the column early on, when they're near the bottom 4. The shorter hydrocarbons have lower boiling points. They turn into liquid and darin out much later on, near the top of the column where it's cooler 5. Bubble caps in the fractioning column stop the separated liquids from running back down the column and remixing. You end up with the crude oil separated into different fractions. Each fraction contains a mixture of hydrocarbons with similar boiling points.

Answer 56

Refinary gases Gasoline (petrol) Naptha Kerosene (paraffn) Diesel Fuel oil (gas oil) Bitumen

Answer 57

a much purer ethanol

Answer 58

high temperatures: 300^oc high pressures: 60 - 70 atmospheres needs a high input of energy

Answer 59

fermentation: high labour costs hydration of ethene: low labour costs

Answer 60

carbon dioxide and water

Answer 61

the removal of water from a compound

Answer 62

Crude oil is burned for **energy** but this can produce **pollutants**

Answer 63

crude oil was formed millions of years from remains of dead organisms (dead sea creatures) huge numbers of microscopic animals and plants died and fell to the bottom of the sea - their remains were covered in mud layers of sediment formed on top of them and their shells and skeletons formed limestone the soft tissue was gradually changed by high temperatures and pressures into crude oil crude oil is less dense than the water in rocks so it will rise as a result of pressure from below and often escape altogether if the rocks are permeable (if the rocks are impermeable, oil can't rise through and gets trapped)

Answer 64

a finite, non-renewable resource

Answer 65

a mixture of substances, most of which are hydrocarbons

Answer 66

as the molecules get bigger, the boiling point increases large molecules are attracted to each other more strongly than smaller ones more heat is needed to break these stronger attractions to produce the widely separated molecules in the gap

Answer 67

as the molecules get bigger, the liquids become less volatile (the more slowly it evaporates at room temperature) this is because bigger molecules are more strongly attracted to their neighbours and so don't turn turn to a gas so easily

Answer 68

the tendency of a substance to vaporize

Answer 69

as the molecules get bigger, they become more viscous (flow less easily) liquids containing small hydrocarbon molecules are runny those containing large molecules are much stickier because of greater attractions between their molecules

Answer 70

bigger hydrocarbons do not burn as easily as their smaller ones this limits the use of the bigger ones as fuels

Answer 71

by fractional distillation

Answer 72

more carbon atoms less commercially useful

Answer 73

10 carbons

Answer 74

15 carbons

Answer 75

1. Start by heating the paraffin. After a few seconds, move the Bunsen burner to heat the silica or alumina catalyst. Alternate between the two until the paraffin vaporises and the catalyst glows red 2. The heated paraffin vapour cracks as it passes over the heated catalyst 3. Smaller alkanes collet at the end of the boiling tube, while alkene gases travel down the delivery tube 4. The alkenes are then collected through water using a gas jar

Answer 76

20 carbons

Answer 77

40 carbons

Answer 78

70+ carbons

Answer 79

a physical process - there are no chemical reactions

Answer 80

commonly used as liquefied petroleum gas (LPG) for domestic heating and cooking

Answer 81

fuel (petrol) for cars

Answer 82

find the section of the polymer that's repeated

Answer 83

used in the chemical industry as a 'feedstock' (starting material) to make: plastics; dyes; drugs; explosives; paints

Answer 84

take the repeat unit and add a double bond

Answer 85

fuel for jet engines domestic heating oil 'paraffin' for small heaters and lamps

Answer 86

fuels for enginesin some cars, buses, lorries, boats and railways engines where the line hasn;t been electrified some is also cracked to make other organic chemicals and produce more petrol

Answer 87

domestic central heating fuel for big ships boilers for ships

Answer 88

melted and mixed with rock chippings to make surfaced for roads and asphalt for roofs

Answer 89

1. The amounts of each fraction you get will depend on the properties of the various hydrocarbons in the original crude oil, not the amount in which they are needed. Far more petrol is needed, for example, than is found in crude oil 2. Apart from burning, the hydrocarbons in crude oil are fairly unreactive. To make other organic chemicals from them, they must first be converted into something more reactive

Answer 90

they are not very useful

Answer 91

Long hydrocarbons have **high** boiling points are are **viscous**

Answer 92

Shorter hydrocarbons have **low** boiling points and are much **thinner** and **paler** in colour

Answer 93

cracking is a form of thermal decomposition because the larger molecules are broken down into simpler molecules by heating them

Answer 94

the gas oil fraction is heated to give a gas vaporised hydrocarbons are passed over a powdered catalyst of mixed silicon dioxide/silica (SiO₂) and aluminum oxide (Al₂O₃) at about 600^oC to 700^oC

Answer 95

amixture of alkanes and alkenes some reactions even produce a small percentage of free hydrogen

Answer 96

Cracking breaks up molecules in a **fairly random** way

Answer 97

making alkenes for plastics turning bitumen and candle wax (of limited use) into things like petrol and cooking gas (which are very useful)

Answer 98

the joining up of lots of little molecules (the monomers) to make one big molecule (the polymer)

Answer 99

addition condensation

Answer 100

A polymer is a chemical **compound** made of **many smaller, identical molecules** (called **monomers**) linked together

Answer 101

Under high pressure and with a cataylst to help them along, many small molecules containing a carbon-carbon double bond will open open up (break) the double bonds and join together (polymerise) to form very long, saturated chains - polymers

Answer 102

In addition polymerisation, **alkenes** add to themselves As this addition proceeds further a **long, molecular chain** is formed The alkene is a **repeating unit** in the chain (the monomer) - the chain itself is the **polymer**

Answer 103

there are two methyl groups attached to the second and third carbon atom in the chan

Answer 104

the name comes from the monomer it's made from - you just put brakets around the monomer and stick the word 'poly' in front of it e.g. poly(ethene)

Answer 105

number 1 as it has higher intermolecular force of attraction as the chain is a straight line - it harder to break

Answer 106

plastics are formed when lots of small molecules (monomers) join together to make a polymer

Answer 107

most polymers are hard to get rid of

Answer 108

most addition polymers are inert (they don't react easily) - this is because of the carbon-carbon covalent bonds in the polymer chain are very strong and aren't broken down easily this means that it takes a really long time for addition polymers to biodegrade (be broken down by bacteria or other living organisims) - if you bury them in a landfill site, they'll stil be there years later burning plastics can release toxic gases

Answer 109

it is difficult to dispose of polymers the best thing is to reuse them as many times as possible and then recycle them

Answer 110

low density poly(ethene) (LDPE) high density poly(ethene) (HDPE)

Answer 111

thin film to make polythene bags it is very flexible and light but not very strong

Answer 112

plastic bottles such as milk bottles it hs rather greater strengh and rigidity than low-density poly(ethene)

Answer 113

packaging such as plastic bags, bottles and other containers it is a light, stretchable polymer

Answer 114

poly(propene)

Answer 115

ropes crates kettles food containers carpets it's a very tough polymer, but it's relatively flexible and resistant to heat

Answer 116

poly(chloroethene) it is usually known by is old name, polyvinlychloride or PVC

Answer 117

it is quite strong and rigid: drainpipes, replacement windows it can be made flexible by adding 'plasticisers': sheet floor coverings it doesn't conduct electricity: insulating electrical cables

Answer 118

it usually involves two differnt types of monomer joining together alternately the monomers react together and bonds form between them, making polymer chains for each new bond that forms, a small molecule (for example, water) is lost

Answer 119

- COOH group e. g. ethanoid acid in vinegar = CH₃COOH

Answer 120

it shows how the atoms are joined up it can be either be drawn as displayed formula or written out as, for example, CH₃CH₂CH₃ (C₃H₈)

Answer 121

a pair of shared electrons

Answer 122

1. identify the largest carbon chain 2. number from heaviest side first - a double bond is heaviest (so put it on lowest carbon possible), read left to right or right to left to which carbon 3. identify groups attached - e.g. 1C = methyl 4. identify type of molecule 5. prefix (group) - suffix (type)

Answer 123

molecules with the same molecular formula, but with different structural formulae

Answer 124

draw the longest carbon chain horizontally