ORGANIC Chem

• What's the name of the mechanism where a hydrogen halide is added to an alkene and what's the product?

  Electrophilic addition. The product is a haloalkane.
• What's the name of the mechanism where a halide is added to an alkene and what's the name of the product?

  Mechanism: Electrophilic addition

  Product: dihalogenoalkane
• What's the name of the mechanism where an alkene reacts with sulfuric acid and what's the product?

  mechanism: Electrophilic addition

  product: alkyl sulfate
• What allows addition polymers to be solid at room temperature? 


  Because they have very strong Intermolecular forces (which require a lot of energy to be overcome)
• Why do addition polymers have many strong van der waals forces? 


  Because they are very long, so contain many electrons within their chains causing Van der waals forces to arise.
• Why are addition polymers inert? 


  Because the carbon backbone in the addition polymer is made up of strong non-polar bonds.
• What is PVC ? 


  PVC is polychloroethene
• Why can PVC be used to make a variety of products? 


  Because PVC is rigid due to its many strong Intermolecular forces between chains.
• Why can PVC be used in flexible plastics ? 


  Because PVC can be made flexible using plasticisers
• What are plasticisers and how do they work? 


  Act as a spacer between PVC chains separating them so that the Intermolecular forces between chains are reduced. Reduced intermolecular forces between chains allows the PVC to bend and not snap.
• Why may some polymers be difficult to biodegrade?

  Because they contain C=C or C-C bonds that are non-polar, strong covalent bonds that can't be attacked by nucleophiles
• Why are halogenoalkanes polar?


  Due to the difference in electronegativity between carbon and halogen atoms. (i.e the carbon-halogen bonds are polar)
• What forces do halogenoalkanes experience and why?


  dipole-dipole forces and Van Der Waals because the carbon-halogen bond is polar.
• What's the trend in melting points and boiling points of halogenoalkanes and why? 


  They increase as chain length increases because the strength of the VDW forces increase.
• Why are halogenoalkanes only slightly soluble in water?


  Because the hydrogen bonds between water molecules tend to be stronger than the dipole-dipole forces between water molecules and halogenoalkanes.
• What is the trend in solubilities of halogenoalkanes? 


  The solubilities decrease as the chain length increases.
• What is the rate of reaction of halogenoalkanes dependant on and what increases the rate? (i.e nucleophilic substitution reactions of halogenoalkanes)


  The bond enthalpy of the carbon-halogen bond, when it's lower the rate is faster.
• Why is the rate of reaction of halogenoalkanes higher when the the bond enthalpy of the carbon-halogen bond is lower?

  Because when there's lower bond enthalpy, less energy is required for a successful collision, so the proportion of successful collisions increases which increases the rate of the reaction.
• What conditions are required to favour nucleophilic substitution of halogenoalkanes when hydroxides are added, also what's the product?

  Alcohol produced

  Aqueuous hydroxides

  dilute NaOH/KOH

  lower temperatures
• What conditions are required to favour elimination of halogenoalkanes with hydroxides and what's the product produced?

  alkenes produced

  ethanolic hydroxides

  concentrated KOH/NaOH

  higher temperatures
• What do the hydroxides act as in elimination reactions of halogenoalkanes?


  Act as bases (proton acceptors)
• What do the hydroxides act as in nucleophilic substitution?

  Nucleophiles
• Which structure of the halogenoalkanes favours elimination and which favours substitution ?

  Primary halogenoalkanes (not many alkyl groups attached) favours substitution

  Tertiary halogenoalkanes (more alkyl groups attached) favours elimination.
• What alternatives are used to CFC's (chlorofluorocarbons)?

  Hydrofluorocarbons and hydrocarbons
• Why are the alternatives to CFC's (hydrocarbons and hydrofluorocarbons) used instead of CFC's?

  They have stronger bonds (that are less likely to break under UV light so won't catalyse decomposition of ozone layer)

  Can't produce chlorine free radicals
• What's the benefit to life on earth of the ozone in the upper atmosphere

  absorbs harmful UV light
• What's one reason why the use of CFCs was not restricted until several years after Rowland and Molina published their research?

  Any of these:

  lack of evidence that ozone was being depleted

  • lack of alternatives to CFCs

  • commercial interest to continue to use CFCs

  • hard to obtain international agreement
• CFC-11 is a greenhouse gas that can contribute to global warming. State and explain how CFC-11 is able to contribute to global warming.

  It absorbs infrared radiation

  (because) the molecule has polar bonds
• Why do carboxylic acids with the same carbon chain length as aldehydes and ketones have higher melting points and boiling points?

  Because carboxylic acids have hydrogen bonding as well as VDW's and dipole-dipole forces whilst aldehydes and ketones only have VDW's forces and dipole-dipole forces.
• What's the trend in melting and boiling points of carbonyl compounds?

  As the carbon chain length increases the melting and boiling points also increase.
• what's an alkyne and what does its skeletal formula look like?

  An alkyne is a carbon-carbon triple bond and its skeletal formula looks like 3 lines.
• What's a conjugated alkene and what does its skeletal formula look like?

  An alkene with alternating double and single bonds, its skeletal formula looks like alternating double and single lines.
• If given mass charge ratios (m/z) of ions produced for an element , which is the ion that reaches the detector first?

  the ion with the lowest m/z ratio
• why are compounds with delocalised electrons more stable than those without?

  because delocalised electrons spread out so the electron density of the compound decreases