Chapter 2 - Developing Fuels Flashcards
What is enthalpy change
How much heat energy is transferred in a reaction
- exothermic
+ endothermic
What is the enthalpy of combustion
The energy transferred when 1 mole of fuel is burned completely in oxygen
What is the formula for calculating energy transferred
Mass of water x SHC x temp change
What is the formula for enthalpy of combustion
Heat energy transferred / amount of fuel in moles
Describe how to measure enthalpy of combustion
- 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
What is complete combustion
When there is sufficient oxygen available, only carbon dioxide and water are produced
What is incomplete combustion
When there isn’t enough oxygen causing formation of carbon or carbon monoxide
how can you calculate enthalpy changes using bond enthalpies
bonds broken - bonds made
how are oxides of sulfur formed and what are the environmental/health issues associated
- 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
how are oxides of nitrogen formed and what are the environmental/health issue associated
- 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
how is carbon dioxide formed and what are the environmental/health issue associated
- complete combustion of fuel
- causes global warming as it absorbs infrared radiation, raising the temperature of the atmosphere
how is carbon monoxide formed and what are the environmental/health issue associated
- incomplete combustion of fuel
- causes health problems as bonds to haemoglobin in the blood, starving the body from oxygen
how are carbon particulates formed and what are the environmental/health issue associated
- incomplete combustion of fuel
- creates smog which causes asthma and respiratory probelms
how are unburned hydrocarbons formed and what are the environmental/health issue associated
- fuel evaporating/not reacting
- causes smog and breathing problems
what is photochemical smog
a mixture of primary and secondary pollutants, including ground level ozone thats produced by the action of the suns rays on the primary pollutants
whats are the effects of photochemical smog
- haziness and reduced visibility
- eye/nose irritation
- breathing problems
- affects animals and plants
- highly reactive
what is the structure of a catalytic converter
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
what do catalytic converters do
- removes NO, CO and unburned hydrocarbons
- unburned hydrocarbons are oxidised to CO2 and H2O
- NO is reduced by CO to nitrogen gas and CO2
what are catalyst poisons
substances that become strongly adsorbed to the catalyst surface and prevent the intended reactants from binding to the catalyst, slowing the reaction down
what is the ideal gas equation
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
what is a heterogeneous catalyst
a catalyst that is in a different physical state to the reactants
describe the reaction of a heterogeneous catalyst
- 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)
how do you name alkenes
- 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
what is addition polymerisation
when 2 or more monomers join together to give a polymer with no other products
