Wider Impact Of Chemistry, Organic Molecules and Hydrocarbons

Question 1

Chemical process development must consider

Answer 1

Social implications (labour, use of land, impact on local amenities) and economic factors (industry plant sitation, transport, availability of services)

Question 2

Cost of process

Answer 2

Research and development
Capitol cost of plant
Depreciation
Labour costs
Raw materials
Energy costs
Waste disposal costs
Safety measures

Question 3

Environmental factors

Answer 3

Impact on environment and energy consumption

“Polluter pays”

Question 4

Green chemistry, manufacturers must

Answer 4

Keep waste to minimum
Use renewable resources if possible
Keep energy costs to a minimum
Catalysts so low temperatures can be used
Non toxic reactants if possible
Waste products treated to give non toxic materials

Question 5

Alkene formula

Answer 5

CnH2n+2

Question 6

Naming rules

Answer 6

Stem (meth, eth, prop….)
Suffix (ane, ene, yl, ol, oic acid, chloro)
Number the carbons from end closest to side chain
Count longest chain of Carbons
Alphabetical order

Question 7

Alkane formula

Answer 7

CnH2n

Question 8

Alkanes are..

Answer 8

Non polar due to tetrahedral shape and difference in electronegativity, they don’t dissolve in water as they can’t form hydrogen bonds, boiling point increases as chain length increases, branching in chain decreases boiling point

Question 9

How do functional groups affect physical properties?

Answer 9

Boiling point affected by intermolecular forces type and strength
Non polar molecules have weak instantaneous dipole-induced dipole forces
Permanent dipole molecules have stronger dipole-dipole forces
N-H/F-H/O-H have hydrogen bonds

Question 10

Hydrogen bonds in carboxyllic acids create a..

Answer 10

Dimer (2 molecules joined together)

Question 11

Solubility in water for carboxyllic acids and alcohols

Answer 11

Highly soluble
Solubility decreases as chain length increases
Water cannot hydrogen bond with long hydrocarbon chains as they are hydrophobic

Question 12

Structural isomers definition

Answer 12

Compounds with same molecular formula but different structural formula

Question 13

Electrophile definition

Answer 13

Electron pair acceptor

Positive ions/positive part of polar molecule

Question 14

Nucleophile definition

Answer 14

Electron pair donor

Negative ions/negative part of polar molecule

Question 15

Radicals definition

Answer 15

Atom/molecule with an impaired electron, very reactive

Question 16

Heterolytic bond fission

Answer 16

Covalent bond breaks, 2 electrons move into just one of the atoms
Results in positive and negative ions
E.g. Cl2–>Cl+ + Cl-

Question 17

Homolytic bond fission

Answer 17

Covalent bond breaks, 2 electrons move into different atoms

E.g. Cl2–> 2Cl radicals

Question 18

Hydrocarbons definition

Answer 18

Compound of only hydrogens and carbons

Question 19

Bonds in alkanes

Answer 19

Strong
Non polar
Little polarisation (C and H similar electronegativities)
Tetrahedral arrangement negates any dipoles present
Weak van der waals

Question 20

Alkanes are…

Answer 20

Unaffected by ions/polar molecules
Low melting and boiling points (weak Van der Waals)
Insoluble in water

Question 21

Liquid alkanes are…

Answer 21

Good solvents for non polar molecules however don’t dissolve ionic or polar compounds

Question 22

Combustion of alkanes

Answer 22

Good fuels- burn exothermically on presence of oxygen to produce CO2 and water vapour

Question 23

Benefits to burning fossil fuels

Answer 23

Needed for transport, electricity generation, cooking, heating

Question 24

Disadvantage of burning fossil fuels

Answer 24

CO2 (greenhouse gas) leads to global warming
Can for SO2 which contributes to acid rain
Limited supply of oxygen when burning = incomplete combustion forming CO (toxic gas)
Not sustainable (crude oil non-renewable)

Question 25

Halogenoalkanes formula

Answer 25

Alkanes + halogens --(UV light)--> halogenoalkanes

Question 26

Halogenoalkanes is what type of reaction?

Answer 26

Substitution reaction (1 or more H atoms replaced with halogen)

Question 27

Halogenoalkanes used as..

Answer 27

Dry cleaning solvents and refrigerants | No longer used as aerosol propellants as they damage ozone layer

Question 28

Halogenoalkanes require UV light to make so is a ...

Answer 28

Photochemical reaction

Question 29

Photochlorination of methane equation

Answer 29

CH4(g) + Cl2(g) --(UV light)--> CH3Cl(g) + HCl(g)

Question 30

Mechanism of Photochlorination of methane

Answer 30

``` Step 1- initiation UV light breaks Cl2 bond (Homolytic fission) Cl2--(UV light)--> 2Cl• Step 2- propagation CH4 + Cl•--> •CH3 +HCl Methyl radical reacts with Cl2 •CH3 + Cl2--> CH3Cl + Cl• Further substitution (2 further propagation steps) CH3Cl + Cl•--> •CH2Cl + HCl •CH2Cl + Cl2--> CH2Cl2 + •Cl Step 3- Termination 2Cl•--> Cl2 Cl• + •CH3--> CH3Cl 2•CH3--> CH3CH3 ```

Question 31

Hexane can be a product of Photochlorination of methane

Answer 31

2•C3H7--> C6H14 | Formed from 2 radicals

Question 32

Mechanism of reaction of halogens + alkanes in UV light

Answer 32

Radical substitution

Question 33

C-H and C-C form

Answer 33

Sigma bonds

Question 34

C=C bonds form

Answer 34

Pi bonds

Question 35

E-Z isomerism

Answer 35

``` E = opposite Z = same ```

Question 36

Which is E and Z isomers?

Answer 36

Look at 2 groups at one end of double bond in terms of atomic numbers, highest atomic number=highest priority Repeat for other 2 groups Z if high priority groups on same side E is high priority groups on opposite sides

Question 37

Ethene + Bromine

Answer 37

Step 1- electrophyllic attack on double bond Induced dipole in Br2, d+Br joins to one C, other C becomes a carbocation, negative Br ion (heterolytic fission), Br ion bonds to cation using lone pair

Question 38

Mechanism of Ethene + Bromine reaction

Answer 38

Electrophyllic reaction

Question 39

Bromine water

Answer 39

Orange/brown decolourises in presence of alkene

Question 40

Catalytic hydrogenation

Answer 40

H molecules + unsaturated alkenes--> alkane Electrophyllic addition Nickel/Platinum/Palladium catalyst High temp, high pressure

Question 41

Electrophyllic addition of hydrogen to ethene

Answer 41

d+H joins to a C, other C a carbocation, H- ion left, H- joins to carbocation

Question 42

Electrophyllic addition of hydrogen bromide to ethene

Answer 42

d+H joins to C, carbocation, Br- ion joins to carbocation

Question 43

Electrophyllic addition of HBr to propene

Answer 43

d+H joins to a C, carbocation, Br- joins to primary/secondary carbocation

Question 44

Which carbocation is Br likely to join to? | HBr to propene reaction

Answer 44

Secondary carbocation is most stable, has 2 electron releasing groups either side

Question 45

Secondary carbocation of HBr propene reaction forms

Answer 45

2-bromopropane

Question 46

Alkenes + substituted alkenes

Answer 46

Addition polymerisation | Form polymers