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 distinguishes cycloalkanes from alkanes?

  Cycloalkanes have a ring structure and the same general formula as alkenes, but they do not contain double bonds.
• What is the process of fractional distillation used for in relation to alkanes?

  • Separates different lengths of hydrocarbons from crude oil
  • Crude oil is vaporized and enters a distillation column
  • Temperature gradient allows for separation based on boiling points
• At what temperature is crude oil vaporized during fractional distillation?

  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 with lower boiling points rise to the top, while longer chains condense at higher temperatures.
• What are some uses of the fractions obtained from fractional distillation?

  Liquefied petroleum gas (LPG), petrol, diesel oil, kerosene, and bitumen.
• What is cracking in the context of hydrocarbons?

  • Process of breaking down long-chain hydrocarbons into shorter, more valuable ones
  • Produces lighter fractions that are in higher demand
• What are the two types of cracking mentioned?

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

  High temperature (around 1000 degrees Celsius) and high pressure (70 atmospheres).
• What is the main product of thermal cracking?

  Mainly alkenes, which can be used to make polymers.
• What is the role of the zeolite catalyst in catalytic cracking?

  It lowers the temperature needed for the reaction and helps produce aromatic hydrocarbons.
• What are the products of complete combustion of alkanes?

  Carbon dioxide and water.
• What is produced during incomplete combustion of alkanes?

  Carbon monoxide and soot, among other products.
• 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 prevents heat from escaping the Earth
• What is the greenhouse effect?

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

  They clog engines and make buildings dirty.
• What is the main consequence of burning fossil fuels?

  It produces carbon dioxide, a greenhouse gas that contributes to global warming.
• What is the greenhouse effect?

  It is the trapping of heat from the Sun by greenhouse gases like carbon dioxide.
• How does carbon dioxide contribute to global warming?

  It absorbs infrared radiation and emits some of it back to Earth, trapping heat.
• What evidence do scientists monitor to support global warming claims?

  They monitor phenomena like melting glaciers and snowmelt.
• What causes photochemical smog?

  It is caused by the reaction of hydrocarbons and nitrogen dioxide in the presence of sunlight.
• What are the main components that lead to the formation of photochemical smog?

  Hydrocarbons and nitrogen dioxide.
• Why is ozone in the lower atmosphere harmful?

  It is toxic and can harm the respiratory system of animals and humans.
• What is the role of catalytic converters in vehicles?

  They reduce the amount of unburned hydrocarbons and nitrogen oxides released into the atmosphere.
• What causes acid rain?

  It is caused by the release of sulfur dioxide and nitrogen oxides into the atmosphere.
• What is the effect of acid rain on the environment?

  It damages trees, plants, and aquatic life.
• How does sulfur dioxide contribute to acid rain?

  It reacts with oxygen to form sulfuric acid when mixed with water in the atmosphere.
• What process can be used to remove sulfur dioxide from flue gases?

  Wet scrubbing.
• How does wet scrubbing work to reduce sulfur dioxide emissions?

  It neutralizes sulfur dioxide using an alkaline solution like calcium carbonate.
• What are the stages of free radical reactions?

  1. Initiation: Radicals are produced using light.
  2. Propagation: Radicals react with non-radicals to form new radicals.
  3. Termination: Two radicals collide to form a stable molecule.
• What is photodissociation in the context of free radical reactions?

  It is the breaking of a bond using light to produce radicals.
• How is chloromethane produced from methane and chlorine?

  Through a free radical mechanism involving initiation, propagation, and termination steps.
• What happens during the initiation step of chloromethane production?

  Sunlight breaks the Cl-Cl bond, producing two chlorine radicals.
• What is the significance of the termination step in free radical reactions?

  It ends the chain reaction by forming a stable non-radical molecule.
• What is the difference between mono-substitution and multiple substitution in free radical reactions?

  Mono-substitution occurs with limited radicals, while multiple substitution occurs with excess radicals.