Alkanes

• Who is the presenter of the AQA alkanes revision video?

  Chris Harrison
• What is the general formula for alkanes?

  $C_nH_{2n+2}$
• What does it mean for alkanes to be saturated?

  They have no double bonds in their structure
• What are the main elements found in alkanes?

  Hydrogen and carbon
• What is the molecular formula for methane?

  $CH_4$
• What is the molecular formula for ethane?

  $C_2H_6$
• What is the molecular formula for propane?

  $C_3H_8$
• What distinguishes cycloalkanes from alkanes?

  Cycloalkanes have a ring structure
• What is the general formula for cycloalkanes?

  $C_nH_{2n}$
• What is the significance of functional group isomers in alkanes?

  They are different compounds with the same formula
• Why are alkanes considered good fuels?

  They burn readily and produce energy
• What is the process used to separate alkanes from crude oil?

  Fractional distillation
• At what temperature is crude oil vaporized in fractional distillation?

  About 350 degrees Celsius
• What happens to the longest hydrocarbons during fractional distillation?

  They do not vaporize and collect at the bottom
• What is the temperature gradient in a fractional distillation column?

  Cooler at the top, warmer at the bottom
• What type of hydrocarbons come off at the top of the fractional distillation column?

  Short-chain hydrocarbons
• What is LPG an abbreviation for?

  Liquefied petroleum gas
• What is the purpose of cracking in the petrochemical industry?

  To convert heavy fractions into lighter, valuable ones
• What are the two types of cracking?

  Thermal cracking and catalytic cracking
• What conditions are used in thermal cracking?

  High temperature and high pressure
• What is produced mainly from thermal cracking?

  Mainly alkenes
• What catalyst is used in catalytic cracking?

  Zeolite catalyst
• What is the main product of catalytic cracking?

  Mainly aromatic hydrocarbons
• What do alkanes produce when they combust completely?

  Carbon dioxide and water
• What is the equation for the complete combustion of butane?

  Produces carbon dioxide and water
• What is produced during incomplete combustion of alkanes?

  Carbon monoxide and soot
• Why is carbon monoxide dangerous?

  It binds to hemoglobin, preventing oxygen transport
• How can carbon monoxide be removed from exhaust gases?

  Using a catalytic converter
• What is the environmental impact of burning fossil fuels?

  It produces carbon dioxide, a greenhouse gas
• What is the greenhouse effect?

  Heat is trapped by greenhouse gases like CO2
• How do greenhouse gases affect global warming?

  They absorb and emit infrared radiation
• What do particulates in engines cause?

  They make buildings dirty and clog engines
• What is the result of burning fuels?

  It can produce complete or incomplete combustion
• What greenhouse gas is produced by burning fossil fuels?

  Carbon dioxide
• How do greenhouse gases contribute to global warming?

  They absorb and emit infrared radiation
• What is the greenhouse effect?

  Heat is trapped by carbon dioxide
• What evidence do scientists use to monitor global warming?

  Melting glaciers and snowmelt
• What causes photochemical smog?

  Burning fossil fuels and nitrogen dioxide
• Where does ozone form that is harmful?

  In the lower atmosphere
• What is the role of hydrocarbons in smog formation?

  They react with nitrogen dioxide to form ozone