Chapter 2 - Developing Fuels

Question 1

What is enthalpy change

Answer 1

How much heat energy is transferred in a reaction
- exothermic
+ endothermic

Question 2

What is the enthalpy of combustion

Answer 2

The energy transferred when 1 mole of fuel is burned completely in oxygen

Question 3

What is the formula for calculating energy transferred

Answer 3

Mass of water x SHC x temp change

Question 4

What is the formula for enthalpy of combustion

Answer 4

Heat energy transferred / amount of fuel in moles

Question 5

Describe how to measure enthalpy of combustion

Answer 5

• measure the initial mass of fuel and water and initial temperature of the water
• burn the fuel and stir the water
• record the final mass of fuel and the final water temperature
• calculate the amount in miles of fuel burned
• calculate the energy transferred to the water
• calculate the enthalpy change per mole of fuel burned

Question 6

What is complete combustion

Answer 6

When there is sufficient oxygen available, only carbon dioxide and water are produced

Question 7

What is incomplete combustion

Answer 7

When there isn’t enough oxygen causing formation of carbon or carbon monoxide

Question 8

how can you calculate enthalpy changes using bond enthalpies

Answer 8

bonds broken - bonds made

Question 9

how are oxides of sulfur formed and what are the environmental/health issues associated

Answer 9

• sulfur in fuel reacts with oxygen in the air at high temperatures in engines
• reacts with water to form sulfuric acid which causes acid rain

Question 10

how are oxides of nitrogen formed and what are the environmental/health issue associated

Answer 10

• nitrogen in the air reacts with oxygen in the air at high temperatures in engines
• reacts with water to form nitric acid which causes acid rain

Question 11

how is carbon dioxide formed and what are the environmental/health issue associated

Answer 11

• complete combustion of fuel

- causes global warming as it absorbs infrared radiation, raising the temperature of the atmosphere

Question 12

how is carbon monoxide formed and what are the environmental/health issue associated

Answer 12

• incomplete combustion of fuel

- causes health problems as bonds to haemoglobin in the blood, starving the body from oxygen

Question 13

how are carbon particulates formed and what are the environmental/health issue associated

Answer 13

• incomplete combustion of fuel

- creates smog which causes asthma and respiratory probelms

Question 14

how are unburned hydrocarbons formed and what are the environmental/health issue associated

Answer 14

• fuel evaporating/not reacting

- causes smog and breathing problems

Question 15

what is photochemical smog

Answer 15

a mixture of primary and secondary pollutants, including ground level ozone thats produced by the action of the suns rays on the primary pollutants

Question 16

whats are the effects of photochemical smog

Answer 16

• haziness and reduced visibility
• eye/nose irritation
• breathing problems
• affects animals and plants
• highly reactive

Question 17

what is the structure of a catalytic converter

Answer 17

platinum catalyst dispersed on a ceramic honeycomb support. has an oxygen sensor to enure exact concentration of CO is produced by the engine to remove NO

Question 18

what do catalytic converters do

Answer 18

• removes NO, CO and unburned hydrocarbons
• unburned hydrocarbons are oxidised to CO2 and H2O
• NO is reduced by CO to nitrogen gas and CO2

Question 19

what are catalyst poisons

Answer 19

substances that become strongly adsorbed to the catalyst surface and prevent the intended reactants from binding to the catalyst, slowing the reaction down

Question 20

what is the ideal gas equation

Answer 20

PV=nRT

• p is pressure
• V is volume
• n is the number of moles
• R is the gas constant (8.31)
• T is temperature in kelvin

Question 21

what is a heterogeneous catalyst

Answer 21

a catalyst that is in a different physical state to the reactants

Question 22

describe the reaction of a heterogeneous catalyst

Answer 22

• catalyst is adsorbed (sticks to) the catalyst surface
• bonds in reactants are weakened and break
• new bonds form to make the products
• product diffuses away from the surface (desorbed)

Question 23

how do you name alkenes

Answer 23

• name the longest carbon chain
• number the position of the start of the double bond keeping the number as small as possible
• number and name any other groups

Question 24

what is addition polymerisation

Answer 24

when 2 or more monomers join together to give a polymer with no other products

Question 25

what is a co-polymer

Answer 25

a polymer made from using more than one monomer

Question 26

what is an electrophile

Answer 26

an ion or molecule that can form a covalent bond to an electron-rich atom by accepting a pair of electrons

Question 27

what must a molecule have to have E/Z isomerism

Answer 27

2 different groups on each end of the double bond

Question 28

what is definition of standard enthalpy of reaction

Answer 28

enthalpy change when the molar quantities written in the equation react under standard conditions

Question 29

what is the definition of standard enthalpy of combustion

Answer 29

enthalpy change when one mole of a substance is burnt completely in oxygen under standard conditions in standard states

Question 30

what is the definition of standard enthalpy of neutralisation

Answer 30

when 1 mole of H+ reacts with 1 mole of OH- to form 1 mole of H2O

Question 31

what is the definition of standard enthalpy of formation

Answer 31

when 1 mole of a compound is formed from its elements under standard states

Question 32

what is Hess’s law

Answer 32

the enthalpy change for a reaction is independent of the route taken from reactants to products, providing the conditions stay the same

Question 33

what are aliphatic hydrocarbons

Answer 33

• contains no benzene rings

- alkanes, cycloalkanes and alkenes

Question 34

what are aromatic hydrocarbons

Answer 34

• contains benzene rings

- arenes

Question 35

what happens in catalytic cracking

Answer 35

larger hydrocarbon molecules are heated with a catalyst and undergo thermal decomposition reactions to form shorter hydrocarbons. one of the products will always be an alkene

Question 36

why is catalytic cracking useful

Answer 36

• shorter hydrocarbons are more useful as fuels

- alkenes are useful as a feedstock for the polymer industry

Question 37

what is a structural isomer

Answer 37

same molecular formula but different structural formula