Alkanes

• What is the general formula for alkanes?

  C$n$H$2n +$$2$
• What does it mean for alkanes to be saturated?

  It means they contain no double bonds and have the maximum number of hydrogen atoms.
• What are the first three alkanes and their formulas?

  Methane (CH₄), Ethane (C₂H₆), Propane (C₃H₈)
• What are cycloalkanes and how do they differ from alkanes?

  Cycloalkanes have the same general formula as alkenes but are saturated and do not contain double bonds.
• What is the primary source of alkanes?

  Crude oil
• What is the process of fractional distillation used for in relation to alkanes?

  • Separates different lengths of hydrocarbons from crude oil
  • Involves heating crude oil to vaporize it
  • Uses a temperature gradient in a distillation column
  • Collects fractions based on boiling points
• At what temperature is crude oil vaporized during fractional distillation?

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

  They do not vaporize and run to the bottom of the column.
• How does the temperature gradient in the fractional distillation column affect the separation of hydrocarbons?

  Shorter chains rise to the top where it is cooler, while longer chains condense at higher temperatures.
• What are some uses of the fractions obtained from fractional distillation?

  Used in LPG, petrol, diesel, kerosene, and bitumen.
• What is cracking in the context of hydrocarbons?

  • A process to break down long-chain hydrocarbons into shorter, more valuable ones
  • Produces lighter fractions that are in higher demand
  • Involves thermal and catalytic cracking methods
• What are the two types of cracking mentioned in the study material?

  Thermal cracking and catalytic cracking
• What is the temperature and pressure used in thermal cracking?

  Approximately 1000 degrees Celsius and 70 atmospheres of pressure
• What is the main product of thermal cracking?

  Mainly alkenes
• What is the role of a zeolite catalyst in catalytic cracking?

  It lowers the temperature needed for the reaction and speeds it up.
• What are the combustion products of alkanes when burned completely?

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

  2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O
• What is incomplete combustion and what are its products?

  Incomplete combustion occurs with limited oxygen supply, producing carbon monoxide and soot.
• Why is carbon monoxide dangerous to human health?

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

  By using a catalytic converter that oxidizes it to carbon dioxide.
• What are the environmental impacts of burning fossil fuels?

  • Produces carbon dioxide, a greenhouse gas
  • Contributes to global warming
  • Absorbs infrared radiation and traps heat in the atmosphere
• What is the greenhouse effect?

  It is the warming effect caused by greenhouse gases trapping heat in the atmosphere.
• What problems do particulates cause in engines?

  They clog engines and make buildings dirty.
• What is the main purpose of filters in cars?

  To remove or stop particulates from causing problems in the engine.
• What is complete combustion?

  It is the burning of fuel that produces carbon dioxide and water as products.
• What greenhouse gas is primarily produced by burning fossil fuels?

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

  They absorb infrared radiation from the Sun and emit some of it back to Earth.
• What is the greenhouse effect?

  It is the trapping of heat in the Earth's atmosphere by greenhouse gases.
• What evidence do scientists monitor to support global warming claims?

  Melting glaciers and snowmelt.
• What is photochemical smog?

  It is a type of air pollution formed by the reaction of sunlight with hydrocarbons and nitrogen oxides.
• What causes the formation of ozone at lower levels of the atmosphere?

  It is formed when hydrocarbons and nitrogen dioxide react in the presence of sunlight.
• What are the main sources of hydrocarbons and nitrogen dioxide in the atmosphere?

  Cars and factories.
• How does photochemical smog affect human health?

  It harms the respiratory system.
• Why is ozone in the lower atmosphere considered toxic?

  Because it can cause respiratory problems in humans and animals.
• What causes the formation of nitrogen oxides in the atmosphere?

  They are formed when nitrogen and oxygen react under high pressure and temperature in engines.
• How do catalytic converters help reduce air pollution?

  They remove unburned hydrocarbons and prevent nitrogen oxides from entering the atmosphere.
• What is acid rain?

  Rain that contains sulfuric acid and nitric acid due to the burning of fossil fuels.
• What damage does acid rain cause?

  It damages trees, plants, and aquatic life.
• What is the process that forms sulfur dioxide when burning fossil fuels?

  The sulfur in fossil fuels reacts with oxygen to form sulfur dioxide.
• How does sulfur dioxide contribute to acid rain?

  It rises into the atmosphere, mixes with water, and forms sulfuric acid.