Alkanes Flashcards
what are the products of complete combustion?
CO2 + H2O
what are the products of incomplete combustion
CO(g) + H2O
or
C(s) +H2O
pollutants from complete combustion
CO2
H2O
-greenhouse gases results in global warming
what is the greenhouse effect?
-UV wavelength radiation passes through the atmosphere to the Earth’s surface and heats up Earth’s surface.
-Earth radiates out infrared long wavelength radiation
pollutants from incomplete combustion
-carbon monoxide- toxic
-Soot: leads to global dimming and respiratory problems
Unburnt hydrocarbons : smog
what is a product if an organic compound contains sulphur
SO2(g)
what is a product if an organic compound contains nitrogen
NO(g)
what are any unwanted organic compounds found in fuels called?
impurities
what is the problem of sulphur dioxide in the atmosphere
causes respiratory issues
-acid rain : makes soil more acidic: harder for crops to grow, makes lakes more acidic harming aquatic animals
how can chemistry reduce the amount of sulfur dioxide released into the atmosphere
b) equation
-by passing them through a scrubber which contain solid calcium oxide which reacts with the sulfur dioxide in a neutralisation reaction
b) SO2 + CaO–> CaSO3
what pollutant can a petrol engine produce via comnustion
soot
water vapour
unburnt hydrocarbon
what is the problem of nitric oxide in the atmosphere
acid rain
respiratory issues
write the equation which represents the reaction nitrogen undergoes in an engine
b) conditions needed for this reaction to occur
N2(g) + O2(g)–> 2NO(g)
b) very high temp
write the equations which represent how nitrc oxide causes acid rain
equation 1)
2NO+ O2–> 2NO2
equation 2)
4NO2+ O2+2H20–> 4HNO3
what is the equation between sulfur dioxide and calcium oxide
b) type of reaction?
SO2(g)+ CaO(s)–> CaSO3(s)
b) neutralisation and acid base
What are the advantages of using a mesh coated with calcium oxide to remove
SO2 from waste gases?
- mesh leads to bigger SA for calcium oxides
-mesh leads to more frequent particle collisions
outline process of fractional distillation
1) crude oil is heated in a furnace to make a vapour
2) column has a negative temperature gradient
3) fractions seperate by boiling point
4) larger molcules condense nearer the bottom of the column
outline the name of the fractions from bottom to top
1) Bitumen
2) Fuel Oil
3) Lubricating oil
4)Diesel Oil
5) Kerosene
6) Petrol
7) Gas
What is Bitumen used for
roofing+ tarmac
what is fuel oil used for
ships
what is Diesel Oil used for
diesel fuel
what is kerosene used for
jet fuel + heating
what is petrol used for
petrol cars
what is gases used for
gas stove
define cracking
conversion of large hydrocarbons to smaller hydrocarbon molecules by breakage of C-C bonds
what is the economic reasons for cracking
The petroleum fractions with shorter C chains are in more demand than larger fractions.
The products of cracking are more valuable than the starting materials (e.g. ethene used to make poly(ethene), branched alkanes
for motor fuels, etc.)
conditions needed for thermal cracking
High temperature ( 1000 °C)
High pressure ( 70 atm/ 7000kPa)
what are the products of thermal cracking
produces mostly alkenes
conditions needed for catalytic cracking
-High temp (450°C)
-Slight pressure
-zeolite catalysts used which helps lower the temperature needed.
products of catalytic cracking
Produces branched and cyclic
alkanes and aromatic hydrocarbons
for motor fuels
Explain how CO and NO are removed from the exhaust gases and why the
removal of each of them is desirable
1)Catalytic converter
2) uses Pt / Rh / Pd / Ir
3)reduces EA
4)2NO + 2CO → N2 + 2CO2
Identify a catalyst used in a catalytic converter
Platinum or palladium or rhodium
Write an equation to show how nitrogen monoxide is removed from the
exhaust gases as they pass through a catalytic converter.
2NO + 2CO → N2 + 2CO2
Outline the essential features of the fractional distillation of crude oil that enable the
crude oil to be separated into fractions.(4)
Fractions or hydrocarbons or compounds have different boiling points
bp depends on size
Temp gradient in column
heavier molecules at bottom
Write an equation to show how one molecule of C14H30 is cracked to form one
molecule of C8H18 and one molecule of another hydrocarbon.
Explain why oil companies need to crack ‘suitable heavy fractions (4)
Large molecules or compounds or long chain hydrocarbons (broken) into smaller molecules or compounds or smaller
chain hydrocarbons;
Zeolite or aluminosilicate (catalyst);
C14H30 → C8H18 + C6H12;
Smaller chain molecules are in more demand or have higher
value or vice versa;
Write an equation for the incomplete combustion of C8H18 to form carbon monoxide and water only.
A catalytic converter is used to remove carbon monoxide from the exhaust gases in a car.
Identify a catalyst used in the catalytic converter.
Write an equation to show how carbon monoxide is removed in a catalytic converter.
State why the water produced in the exhaust gases may contribute to global
warming.
C8H18 + 8½ O2 → 8CO + 9H2O;
Rh/ Pd/Pt/lr
2CO + 2NO → 2CO2 + N2 / 2CO + O2 → 2CO2;
Greenhouse gas
