Chapter 12 pmt flashcards

• What is an alkane?

  A saturated hydrocarbon containing C-H bonds only
• What is the general formula of an alkane?

  $C_nH_{2n+2}$
• Are alkane bonds polar? Why or why not?

  No, they are nonpolar due to similar electronegativities
• What is the shape and angle of an alkane?

  Tetrahedral with a 109.5° angle
• Describe the sigma bond in alkanes.

  It is a covalent bond with direct overlap of electron clouds
• What type of intermolecular forces do alkanes have? Why?

  London forces due to induced dipole-dipole interactions
• What happens to the boiling point as alkane chain length increases? Why?

  The boiling point increases due to more surface area
• Does a branched molecule have a lower or higher boiling point compared to an equivalent straight chain? Why?

  Lower boiling point due to fewer surface area interactions
• Are alkanes soluble in water? Why?

  No, because water's hydrogen bonds are stronger
• How reactive are alkanes?

  Very unreactive
• What reactions will alkanes undergo?

  Combustion and reaction with halogens
• What type of reaction is combustion?

  Oxidation reaction
• What is complete combustion?

  Combustion with a plentiful supply of air
• What are the products of complete combustion when alkanes are used?

  Carbon dioxide and water
• What is the colour of the Bunsen burner flame during complete combustion?

  Blue flame
• What is incomplete combustion and what products are formed in the case of alkanes?

  Combustion in limited oxygen; products: water, CO2, CO
• Write an equation for the complete combustion of propane.

  $C_3H_8 +$$5O_2 \rightarrow 3CO_2 +$$4H_2O$
• Which type of hydrocarbon is most likely to undergo incomplete combustion?

  Longer chains
• What is the environmental impact of carbon monoxide?

  It is toxic and poisonous
• What is the environmental impact of soot (carbon)?

  Causes asthma, cancer, global dimming
• How are halogenoalkanes formed from alkanes?

  Through radical substitution
• In the presence of what do alkanes react with halogens?

  UV light
• What are the three stages of free radical substitution?

  Initiation, propagation, termination
• Write equations for the reaction of CH4 with Cl2 to form CH3Cl.

  Initiation: $Cl_2 \rightarrow 2Cl•$, Propagation: $Cl• +$$CH_4 \rightarrow HCl +$$•CH_3$, Termination: $•CH_3 +$$Cl• \rightarrow CH_3Cl$