Developing Fuels - Organic Chemistry

Question 2

What are aliphatic molecules?

Answer 2

molecules based on chains of carbon atoms

Question 3

Define a structural isomer

Answer 3

An isomer with the same molecular formula but different structural formula

Question 4

Define a catalyst

Answer 4

A substance that increases rate of reaction by providing an alternate reaction pathway with a lower activation enthalpy and isn’t used up during the reaction

Question 5

Define heterogeneous catalysis

Answer 5

When the reactants and catalyst are in different physical states

Question 6

Define homogeneous catalysis

Answer 6

When the reactants and catalyst are in the same physical state

Question 7

What is the first stage of heterogeneous catalysis?

Answer 7

the reactants are adsorbed onto the surface of the catalyst

Question 8

Define adsorption

Answer 8

When a substance sticks to the surface of another substance

Question 9

Describe the process of heterogeneous catalysis

Answer 9

1. Reactants adsorb onto the catalyst
2. Intermediates form as reactant bonds are broken
3. Product bonds form
4. Deadsorption of product from catalyst

Question 10

What is an electrophile?

Answer 10

A molecule that can accept a pair of electrons to form a covalent bond

Question 11

Describe the difference between a π bond and a σ bond?

Answer 11

A σ bond is the original, stronger covalent bond formed directly between the 2 nuclei.

A π bond overlaps a σ bond, with one electron above and one below. These are weaker as the electrons are further from the nucleus

Question 12

What does a lowercase delta (𝛿) represent?

Answer 12

a smalle charge, usually on a dipole

Question 13

What do curly arrows represent in a mechanism?

Answer 13

2e- moving

Question 14

What are the conditions needed for industrial hydrogenation?

Answer 14

Ni catalyst

150 degrees

Question 15

What are the conditions needed for lab hydrogenation?

Answer 15

room temp + pressure

Pt catalyst

Question 16

What are the conditions for industrial hydration of ethene?

Answer 16

phosphoric acid - catalyst

high temp and pressure

Question 17

What is the molar volume of a gas at rtp?

Answer 17

24dm³

Question 18

Describe the conditions of rtp

Answer 18

298K or 25 degrees celcius

1 atmosphere

Question 19

What is the ideal gas law?

Answer 19

pV = nRT

or

pressure x volume = moles x gas constant x temp

note that temp must be in Kelvin

Question 20

When is the ideal gas law used?

Answer 20

When the conditions aren’t rtp

Question 21

Define a polymer

Answer 21

a large molecule based on a repeating unit (monomer)

Question 22

What are the 2 types of polymer?

Answer 22

amorphous and crystaline

Question 23

What is an amorphous polymer?

Answer 23

A low density polymer where the chains are not structured and intertwine

Question 24

What is a crystaline polymer?

Answer 24

A high density polymer where the chains are ordered in rows and are more tightly packed together

Question 25

Name 2 polymers

Answer 25

polychloroethene or PVC (polyvinylchloride)

polyphenylethene or polystyrene

Question 26

What is the monomer for PVC?

Answer 26

Question 27

What is the monomer for polystyrene?

Answer 27

Question 28

What is chain isomerism?

Answer 28

When a chain is either added to a smaller molecule or is in a different place, but still has an overall same molecular formula

eg pentane and methylbutane

Question 29

What is functional group isomerism?

Answer 29

the functional group is attached to a different C atom

eg butan-1-ol and butan-2-ol

Question 30

Define stereo isomerism

Answer 30

same molecular formula + bonds but different spacial arrangement of the atoms

Question 31

What is an example of stereo isomerism?

Answer 31

geometric isomerism

Question 32

Describe geometric isomerism

Answer 32

A C

\ /

C = C

/ \

B D

Where a != b and c != d

Question 33

What are examples of geometric isomerism?

Answer 33

E and Z isomerism

Cis and Trans isomerism

Question 34

What are E and Z isomerism and cis and trans isomerism?

Answer 34

Z and cis = the biggest groups are on the same side of the molecule

E and trans = the biggest groups are on opposite sides of the molecule

Question 35

What is an instantaneous dipole?

Answer 35

Electrons move freely throughout molecules, they aren’t static.

When more electrons happen to be on one side of the molecule, one side is 𝛿+ and one is 𝛿-

This produces an induced / instantaneous dipole

Question 36

What is the role of induced dipoles in intermolecular forces?

Answer 36

The 𝛿+ end of the dipole will attract the 𝛿- end of another dipole (and vice versa)

This attraction is the intermolecular force that holds molecules together

Question 37

How does size affect instantaneous dipoles?

Answer 37

The larger the molecule, the bigger the effect as there are more electrons

Question 38

How does the shape of a molecule affect instantaneous dipoles?

Answer 38

Spherical molecules or chains with bends/branches have a reduced effect

E or cis-isomers have an increased effect

Question 39

What is the equation for the complete combustion of heptane?

Answer 39

C₇H₁₆ + 11O₂ -> 7CO₂ + 8H₂O

Question 40

What is the equation for the incomplete combustion of heptane, where CO is produced?

Answer 40

C₇H₁₆ + 7.5O₂ -> 7CO + 8H₂O

Question 41

What is the equation for the incomplete combustion of heptane where c particulates are produced?

Answer 41

C₇H₁₆ + 4O₂ -> 7C + 8H₂O

Question 42

How can complete combustion be maximised?

Answer 42

• > suck in more air
• > control the fuel:air ratio -> less fuel and more air
• > hotter engine
• > higher pressure