organic chemistry

Question 1

what is crude oil?

Answer 1

Crude oil a fossil fuel formed mostly from dead sea creatures (eg. plankton). It is the source of many fuels and other chemicals such as plastic.

Question 2

what is crude oil a mixture of

Answer 2

hydrocarbons

Question 3

what are hydrocarbons?

Answer 3

compounds made up of only hydrogen and carbon atoms

Question 4

what are alkanes made up of?

Answer 4

a chain of hydrocarbons

Question 5

fill in a table for the first 4 alkanes. include the number of carbons in the chain, displayed formula, the molecular formula and the name.

Answer 5

google it

Question 6

what’s the general formula for alkanes?

Answer 6

CnH2n+2
take the number of C atoms, x2 and +2 to get H atoms

Question 7

how do the properties of alkanes change?

Answer 7

the properties of alkanes change with the number of carbons in the molecule

Question 8

what happens as the number of C atoms increases in an alkane

Answer 8

• boiling point increases
• viscosity increases
• flammability decreases
• amount of soot/ smoke released when burned increases

Question 9

why does fractional distillation take place?

Answer 9

crude oil is not useful as a mixture of hydrocarbons. it needs to be seperated into different fractions of alkanes and different chain lengths.

Question 10

describe the method of fractional distillation in 6 steps.

Answer 10

1. the crude oil is heated to 350°c
2. most of the alkanes evaporate
3. the different alkane vapours rise up the distillation column (the longest chains flow down the bottom)
4. the column gets colder further up
   5.when the alkane/ fraction cools down below its boiling point, it condenses back into a liquid and flows through a pipe
5. the smallest alkanes (eg methane) stay as gases and leave the column at the very top.

Question 11

what happens when alkanes are burned in a plentiful supply of oxygen?

Answer 11

the carbon oxidises into carbon dioxide and the hydrogen oxidises into water. this is called complete combustion.

Question 12

what does the complete combustion of an alkane produce?

Answer 12

carbon dioxide + water

Question 13

what happens when alkanes are burned without enough oxygen?

Answer 13

incomplete combustion takes place and carbon monoxide or soot is made.

Question 14

long alkanes can be split into a _______ _____________ reaction called cracking

Answer 14

thermal decomposition

Question 15

long alkanes, which are in ____ demand but _____ supply, are cracked to make shorter alkanes, which are ____ in demand but _____ supply.

Answer 15

long alkanes, which are low in demand but high supply are cracked to make shorter alkanes which are high in demand but low in supply

Question 16

catalytic cracking

Answer 16

high temperature & the long alkane vapours passed over a catalyst.

Question 17

steam cracking

Answer 17

long alkane mixed with very high temp & high pressure steam

Question 18

what are the 2 products of cracking an alkane?

Answer 18

1 alkane and 1 alkene

Question 19

draw the cracking of C9H20

Answer 19

makes C6H14 and C3H6

Question 20

alkanes are [saturated / unsaturated]
alkenes are [saturated / unsaturated]

Answer 20

alkanes are saturated, alkenes are unsaturated

Question 21

what can the smaller alkanes be used for after cracking?

Answer 21

better fuels. eg. gasoline, kerosene jet fuel, diesel heating oil

Question 22

draw a table of alkenes 2-5 including the number of C atoms, displayed formula, molecular formula and the name.

Answer 22

google it

Question 23

what’s the general formula for an alkene

Answer 23

CnH2n
take the number of C atoms, x2 to get number of H atoms

Question 24

what happens in addition reactions?

Answer 24

the double bond breaks open and atoms are added to the 2 carbon atoms that were part of the double bond

Question 25

what are polymers?

Answer 25

long chain molecules formed by many monomers bonded together

Question 26

how are addition polymers made?

Answer 26

when many alkenes join together. the c=c bond opens up and each c atom makes a new bond to the next molecule

Question 27

name the polymers based off the monomers: ethene= propene= styrene=

Answer 27

polyethene polypropene polystyrene

Question 28

draw the formula for the 3 polymers: polyethene polychloroethene polypropene

Answer 28

knowunity

Question 29

what’s the step by step tutorial for drawing a polymer?

Answer 29

draw the monomer, but: - make the c=c a c-c - add large brackets - bring the lines out past the brackets - add ‘n’

Question 30

what are alcohols?

Answer 30

a series of organic compounds with the functional group -O-H and names ending in -ol

Question 31

draw a table for the first 4 alcohols including the number of carbons in the chain, the displayed formula, the molecular formula and the name

Answer 31

knowunity

Question 32

what are alcohols used as

Answer 32

- fuels - solvents - disinfectants - alcohol (ethanol)

Question 33

how do alcohols have a neutral pH

Answer 33

they dissolve well in water

Question 34

what are the products of alcohols combusting with oxygen?

Answer 34

CO2 and water

Question 35

what happens when sodium and alcohol react?

Answer 35

sodium reacts with alcohol like it does with water, just less violently. creates a salt and hydrogen gas

Question 36

what do alcohols turn into when reacting with oxidising agents?

Answer 36

compounds called carboxylic acids

Question 37

how can ethanol be made?

Answer 37

by fermentation (yeast, no oxygen, 25°c). once complete, filter out the yeast and distill the water-ethanol mixture

Question 38

what are carboxylic acids?

Answer 38

a series of acidic compounds with the functional group (-COOH)

Question 39

draw a table of the first 4 carboxylic acids including the number of C atoms, displayed formula, molecular formula and name.

Answer 39

knowunity

Question 40

why don’t carboxylic acids release as many H+ ions as other acids?

Answer 40

it’s a weak acid, meaning it doesn’t fully dissociate in water

Question 41

what’s the produce of carboxylic acid + a carbonate?

Answer 41

water, a salt, CO2

Question 42

what’s the products of carboxylic acid + a metal?

Answer 42

hydrogen and a salt

Question 43

what is an ester

Answer 43

a molecule formed by reacting an alcohol with a carboxylic acid.

Question 44

how can you help esters react with alcohol?

Answer 44

the mixture is warmed and concentrated sulfuric acid is added as a catalyst.

Question 45

how can esters be recognised? (name, formula, functional group)

Answer 45

name: ……yl and …..oate formula: ….COO…. functional group: C bonded with =O and -O

Question 46

turn ethanol and ethanoic acid into an ester

Answer 46

knowunity

Question 47

what are esters used for and why?

Answer 47

they’re used in flavourings and perfumes as they have a strong smell and taste, and are volatile meaning they evaporate easily so they’re easier to smell

Question 48

how do condesation polymers form?

Answer 48

when monomers react and join together end to end.

Question 49

what is made each time 2 monomers join in a condensation monomer?

Answer 49

a small molecule like H2O

Question 50

what’s the only way a condensation polymer can work?

Answer 50

if the monomers have 2 functional groups

Question 51

shorten the condensation polymer chain shown on knowunity

Answer 51

knowunity

Question 52

4 examples of condensation polymers in nature

Answer 52

- DNA - starch - cellulose - protein

Question 53

what are the 4 nucleotides in DNA

Answer 53

A, T, C, G

Question 54

what is a nucleotide

Answer 54

a monomer that makes up DNA

Question 55

what are dna molecules made of

Answer 55

2 polymer chains made from 4 different monomers called nucleotides